©2011 SUJEEWANI K EKANAYAKE ALL RIGHTS RESERVED

©2011

SUJEEWANI K EKANAYAKE

ALL RIGHTS RESERVED

POLY(ORGANOPHOSPHAZENES) WITH AZOLYLMETHYLPHENOXY AND

PYRIDINOXY SIDE GROUPS TO BE USED AS PROTON EXCHANGE

MEMBRANES IN FUEL CELLS

A Dissertation

Presented to

The Graduate Faculty of The University of Akron

In Partial Fulfillment

of the Requirements for the Degree

Doctor of Philosophy

Sujeewani K Ekanayake

December, 2011

ii

POLY(ORGANOPHOSPHAZENES) WITH AZOLYLMETHYLPHENOXY AND

PYRIDINOXY SIDE GROUPS TO BE USED AS PROTON EXCHANGE

MEMBRANES IN FUEL CELLS

Sujeewani K Ekanayake

Dissertation

Approved: Accepted:

______________________________ ______________________________ Advisor Department Chair Dr. Wiley J. Youngs Dr. Kim C. Calvo

______________________________ ______________________________ Co-Advisor/Committee Member Dean of the College Dr. Claire A. Tessier Dr. Chand Midha

______________________________ ______________________________ Committee Member Dean of the Graduate School Dr. Michael J. Taschner Dr. George R. Newkome

______________________________ ______________________________ Committee Member Date Dr. Peter L. Rinaldi _____________________________ Committee Member Dr. Thein Kyu

iii

ABSTRACT

Proton Exchange Membrane Fuel Cells (PEMFCs) are of great importance to

many stationary and portable applications. The development of a more efficient, high-

temperature tolerant membrane with a high protonic conductivity has become critical to

the better performance of PEMFCs. Consequently, the focus of current research is more

focused on synthesizing membranes which can function at a non-humidified high

temperature environment.

Because N-heterocycles such as azoles substituted on a polyphosphazene

backbone have been found to be one of the best polymers in this regard, the focus of this

dissertation is primarily on developing PEMs (proton exchange membranes) based on

azole and pyridine substituted phosphazenes. In Chapter 1, an overview on PEMFCs as

well as PEMs that have been synthesized to date is presented. The first part of the

introduction is devoted to sulfonated fluorocarbon-based membrane, Nafion®. Then the

focus slowly shifts towards PEMs based on hydrocarbon polymers. The rest of Chapter 1

mainly revolves around polyphosphazene based PEMs. Chapter 2 describes the synthesis

of trimeric, small-molecule, model compounds for high polymers. A series of

hexakis(azolylmethylphenoxy)cyclotriphosphazenes where the azolyl groups are pyrazol,

1,2,4-triazol and 5-methyltetrazol and all three isomers of

iv

hexakis(pyridinoxy)cyclotriphosphazenes have been synthesized and characterized. The

focus of Chapter 3 is on the synthesis of poly(dichlorophosphazene) by modifying a

literature procedure reported by Wang (Macromolecules 2005, 38, 643-645) via one-pot

in situ polycondensation. Chapter 3 also presents a preliminary study on ring opening

polymerization. The focus of Chapter 4 is completely on the synthesis and

characterization of azole and pyridine substituted polyphosphazenes. Chapter 5 includes

film casting studies from both triazolphenol trimer and polymer to obtain corresponding

composites and blends by mixing with commercially available poly(PMDA-ODA) amic

acid. The cast films were imidized and the degree of imidization was monitored by FTIR.

Acid doping studies of each undoped film was performed prior to reporting proton

conductivity.

v

DEDICATION

To my loving husband, Chaminda, for his exceptional support and patience through all

these years

& to my grandparents, parents and my siblings

vi

ACKNOWLEDGEMENTS

First and foremost I want to thank my advisor Dr. Wiley J. Youngs. Being my

advisor for nearly five years, you have been such an inspiration to me. You were always

there to guide and advise me. I am so thankful for having an advisor like you who was

always so patient, friendly and kind. This dissertation would not have been possible

without your extraordinary support.

My co-advisor, Dr. Tessier A. Claire, your kindness, enthusiasm, and friendliness

along with your unique way of guiding students have always inspired me to pursue my

dream of becoming a teacher one day with more determination. I have learned a lot from

you when it comes to research techniques and teaching. I am going to miss you dearly. I

am so lucky to have both you & Dr. Youngs around me when I am going to close one of

the best chapters in my life.

Dr. Matthew J. Panzner, you were a post-doc in Dr. Youngs’ lab when I joined his

group. If it was not for you, I would have never come this far. You taught me all the

important lab techniques, ran crystals for me, trained me on the NMR instruments with

much patience, and were always there to help whenever I came to you with problems

regarding my research work. I would much appreciate all your help & wish you and your

family all the best of luck.

vii

I would like to thank all the members on my dissertation defense committee, Dr.

Michael J. Taschner Dr. Peter L. Rinaldi and Dr. Thein Kyu, for your valuable time & all

the work you have done to make my dissertation a better one.

I also want to thank Dr. Dominic Gervasio, our collaborator from the University

of Arizona for all the assistance given to me. My special thanks go to DOE. If not for the

funding from DOE, we would not have been able to continue our research. Thank you,

Dr. Robert A. Weiss, for opening your lab doors for us to use Fuel cell test system. Thank

you, Dr. Barton Hamilton, for giving us the chance to use the casting machine. I really

liked your sense of humor. Jon Page, I thank you for training me to run TGA, DSC, FTIR

and also thank you for running GPC for me. I am also thankful for the other staff in the

Department of Chemistry, including Nancy, Jean and the NMR staff for all the support

extended to me during this time period.

All the past members of the Youngs and Tessier group, Aysegul , Semih,

Khadijah, Doug, Tammy, Paul, Tatiana, and Golf (Samitthichai), my hats are off to all of

you for all the encouragement & advice. Thanks Doug for running my crystals. The

recent graduates Jay (Supat), Joanna and Amanda, as well as the current grads Zin-Min,

Dave, Nick, Brian, Nikki, Mike and Pat, I am so happy to have had the chance to work

with you. Nikki, I will always remember your beautiful smile and friendliness. Thanks

Brian for running my crystals. You were always willing to help me whenever I needed it.

Dave, Nick, Zin-Min and Joanna, all the phosphazene people, I had such a wonderful

time with all of you guys. I really enjoyed all the fun times we had together. Thanks a lot

for all the help you have given me during the past these years with glassblowing and

using the high vacuum line. Special thanks should go to Dave for providing me with

viii

chloropolymer, teaching me how to run ROP, and so on. I learned a lot from you, Dave. I

am going to miss you all.

I would also like to extend my gratitude towards my undergraduate college, the

University of Sri Jayewardenepura in Sri Lanka, for all the support and encouragement it

gave me during all this time. You laid a strong foundation for my higher studies and who

I am today. I want to thank Dr. Deraniyagala, then chair of the department of Chemistry,

for all the support given during that time. I am so thankful to Dr. Pradeep M. Jayaweera,

my then research advisor, for giving me a chance to be part of your group. Dr. Susil J.

Silva, Dr. Sudantha Liyanage, Dr. Laleen Karunanayake & Dr. Siromi Samarasinghe,

thank you for all the support and invaluable advice. I also want to thank all the other

professors who taught me and all the non-academic staff of the department of Chemistry

for their support.

Finally, I would like to thank my family and friends for all the contributions &

sacrifices they have made towards my success. Aththa & Mamma, though you two are no

longer here with me today to see my success, I hope I made you proud grandparents. You

were always there for me since I was a toddler, and I will always keep you in my

memories. Amma and thaththa, you worked so hard to bring all of us up to be who we are

today. Amma, you have been the strongest woman I have ever known. You sacrificed a

lot to give us a better life. I am grateful for all of my sisters and one and only brother for

all the support given. James McNenny and Vivienne McNenny, my US host family, you

not only opened your door for us but you also opened your hearts for us even though we

were complete strangers to you. I remember all the good times we had together. I learned

how to play cards. How can I forget all the fun we had together. You warmly welcomed

ix

us and became our adopted parents. I am sure I am going to make you also proud. There

is always a special place for you two in my heart.

My old buddies in the department, Roshinee akka, Nilufer, and Jay, you were

always there to support me. Jay, you were my lab colleague, and I learned a lot from you

during this short period of time. All of you have now moved in different directions. I

wish good luck to all of you. I really miss you guys & please keep in touch. Thanks

Vincenzo for helping me figure out mass spectra. I wish you a successful career.

Chaminda, you are the best thing that happened to me in my life. You have been

my husband and my best friend and gave your unstinting support whenever I needed it.

Thank you!

x

TABLE OF CONTENTS

Page

LIST OF TABLES ..................................................................................................... xvii

LIST OF FIGURES ..................................................................................................... xix

LIST OF SCHEMES.................................................................................................... xxv

LIST OF EQUATIONS ............................................................................................ xxvii

CHAPTER

I. INTRODUCTION TO THE POLYPHOSPHAZENE BASED PROTON EXCHANGE MEMBRANES FOR FUEL CELLS .................................................. 1 1.1 Introduction to Fuel Cells .....................................................................................1

1.1.1 Types of Fuel Cells ..................................................................................... 2

1.1.2 Fuel Cell Operation (PEMFCs and DMFCs) ............................................. 3

1.2 Proton Exchange Membranes/Polymer Electrolyte Membranes (PEMs) .............8

1.2.1. Types of PEMs .............................................................................................9

1.2.1.1 Perfluorinated Polymer Electrolytes .............................................9

1.2.1.2 Alternative Polymer Electrolyte Membranes ..............................12

1.3 Polyphosphazenes ...............................................................................................14

1.3.1 Small-Molecule Model Compounds for Polyphosphazenes ......................15

1.3.2 Polymerization Methods ...........................................................................17

A. Ring Opening Polymerization (ROP) .....................................................17

xi

B. Condensation Polymerization .................................................................17

a. Condensation of PCl5 with Ammonium Chloride ...............................18

b. Condensation of PCl5 and Ammonium Sulfate ..................................18

c. Condensation of Cl3P=NP(O)Cl2 ........................................................19

d. Living Cationic Condensation Polymerization ...................................19

1.3.3 Macromolecular Substitution .....................................................................19

1.3.4 Bond Lengths and Bond Angles in Cyclo and Polyphosphazenes ............21

1.3.4.1 Bonding in Cyclophosphazenes and Polyphosphazenes.............22

1.3.5 Applications of Polyphosphazenes ............................................................27

1.4 Polyphosphazene based PEMs ............................................................................28

1.4.1 Acid Functionalized Polyphosphazenes ....................................................30

1.4.1.1. Sulfonic Acid Functionalized Polyphosphazenes ......................30

A. Sulfonated Polyphosphazenes ..........................................................30

B. Blends of Sulfonated Polyphosphazenes .........................................34

a. Polyphosphazene/Poly(vinylidene fluoride) (PVDF) Blends ......35

b. Polyphosphazene/Polyacrylonitrile (PAN) Blends .....................36

c. Polyphosphazene/Polybenzimidazole (PBI) Blends ...................38

d. Polyphosphazene/Hexa(vinyloxyethoxyethoxy) cyclotriphosphazene (CVEEP) Blends .......................................39

1.4.1.2. Phosphonic Acid Functionalized Polyphosphazenes ..................40

1.4.1.3. Sulfonimide Functionalized Polyphosphazenes .........................47

1.4.2 Low-humidified or Novel Non-humidified PEMs based on Polyphosphazenes ......................................................................................51

A. Polyphosphazene-Phosphoric Acid (PA) Composites as PEMs ..............51

xii

a. Poly(dipropyl)phosphazenes/Poly-paraphenylenesulfide

Composite (PPS-PDPrP-PA) ............................................................52

b. Poly(dipropyl)phosphazenes/Sulfonated poly[(hydroxy)propyl, phenyl ether] Composite (SPHPE-PDPrP-PA) .................................54

c. Poly(diethyl, dipropyl)phosphazene/Naphthalenic sulfonated

Coplyimide (SPI-PDEt, DPrP-PA) .....................................................55

B. Azole Substituted Polyphosphazenes as PEMS .......................................57

1.5 Conclusion ..........................................................................................................60 II. SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF

HEXACYCLOTRIPHOSPHAZENES AS MODEL COMPOUNDS TO POLY(ORGANOPHOSPHAZENES) ......................................................................62

2.1 Introduction ........................................................................................................62

2.2 Results and Discussion ......................................................................................64

2.2.1. Syntheses and Characterizations of Starting Materials ..............................64

2.2.2 Synthesis and Characterization of Hexakis(azolylmethoxyphenoxy)cyclotriphosphazenes ............................68

2.2.3 Synthesis and Characterization of Hexakis(pyridinoxy)cyclotriphosphazenes ................................................73 2.2.4. X-ray Structural Characterization of Hexakis(azolylmethylphenoxy) and Hexakis(pyridinoxy)cyclotriphosphazenes .........................................75 2.2.5. Thermal Analysis of Hexakis(azolylmethylphenoxy) and

Hexakis(pyridinoxy) cyclotriphosphazenes ...............................................79

2.3 Conclusion .........................................................................................................84

2.4 Experimental ......................................................................................................84

2.4.1 General Considerations ..............................................................................84

2.4.2 X-ray Crystallographic Structure Determination Details ..........................86

2.4.3 Synthesis of 4-(1H-pyrazol-1-ylmethyl)phenol (II-I) ..............................86

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2.4.4 Synthesis of 4-(1H-1,2,4-triazol-1-ylmethyl)phenol (II-2) ......................87

2.4.5 Synthesis of 4-(1H-5-methyltetrazol-1-ylmethyl)phenol (II-3) ...............88

2.4.6 Synthesis of Hexakis[4-(1H-pyrazol-1-ylmethyl)phenoxy] cyclotriphophazene (II-4) .........................................................................89 2.4.7 Synthesis of Hexakis[4-(1H-1,2,4-triazol-1-ylmethyl)phenoxy] cyclotriphophazene (II-5) .........................................................................91 2.4.8 Synthesis of Hexakis[4-(1H-5-methyltetrazol-1-lmethyl)phenoxy] cyclotriphophazene (II-6) .........................................................................92 2.4.9 Synthesis of Hexakis(2-pyridinoxy)cyclotriphosphazene (II-7) ...............93

2.4.10 Synthesis of Hexakis(3-pyridinoxy)cyclotriphosphazene (II-8) ...............94

2.4.11 Synthesis of Hexakis(4-pyridinoxy)cyclotriphosphazene (II-9) ................95 III. SYNTHESIS AND CHARACTERIZATION OF

POLY(DICHLOROPHOSPHAZENE) TO BE USED AS THE BACKBONE FOR MACROMOLECULAR SUBSTITUTION.....................................................97

3.1 Introduction .........................................................................................................97

3.2 Results and Discussion .....................................................................................106

3.2.1 One-pot in situ Polycondensation ............................................................106

3.2.2 Ring Opening Polymerization – A Preliminary Study ............................110

3.2.3. Molecular Weight Determination ............................................................118

3.2.4. Thermal Analysis of Phenoxy Polyphosphazenes ...................................123

3.3 Conclusion ........................................................................................................125

3.4 Experimental .....................................................................................................126

3.4.1 General Considerations ............................................................................126

3.4.2 Synthesis of poly(dichlorophosphazene) via one-pot in situ Polycondensation (III-1a) .......................................................................127

xiv

3.4.3 Synthesis of poly(dichlorophosphazene) via ring opening polymerization (III-1b) .....................................................................................................128

3.4.4 Synthesis of poly[bis(diphenoxy)phosphazene] using compound II-1a (III-2a) ...........................................................................................129 3.4.5 Synthesis of poly[bis(diphenoxy)phosphazene] using compound III-1b (III-2b) .........................................................................................130 IV. SYNTHESIS AND CHARACTERIZATION OF POLY(AZOLYLPHENOXY) AND POLY(PYRIDINOXY) PHOSPHAZENES AS CANDIDATES FOR PEMS .............................................................................................................131

4.1 Introduction .......................................................................................................131


4.2.1 Synthesis and Characterization of Azolylmethylphenoxy Polyphosphazenes .....................................................................................133 4.2.2 Synthesis and Characterization of Pyridinoxy Polyphosphazenes ..........140

4.2.2.1 Synthesis via Substitution Route ..............................................140

4.2.2.2. Melt Polymerization Route of Pyridinoxy Cyclotriphosphazenes – A Preliminary Study ..........................143 4.2.3. Thermal Analysis of Azolylmethylphenoxy and Pyridinoxy Polyphosphazenes ....................................................................................146 4.3 Conclusion ........................................................................................................149 4.4 Experimental .....................................................................................................149


4.4.2 Synthesis of poly{bis[4-(1H-1,2,4-triazol-1-ylmethyl)phenoxy]phosphazene} (IV-1) .................................................150

4.4.3 Synthesis of poly{bis[4-(1H-5-methyltetrazol-1-ylmethyl)phenoxy]phosphazene} (IV-2) .................................................151

4.4.4 Synthesis of poly[bis(3-pyridinoxy)phosphazene] (IV-3) .......................152 V. MEMBRANE CASTING, IMIDIZATION AND CONDUCTIVITY STUDIES OF AZOLYLPHENOXY PHOSPHAZENES ........................................................154

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5.1 Introduction .......................................................................................................154

5.1.1 PEMs based on N-Heterocycles ...............................................................154

5.1.2 Imidization Studies ..................................................................................163

5.1.2.1 Synthesis of Poly(amic acid)s-PAAs ........................................163

5.1.2.2 Conversion of PAA into Polyimide ..........................................164


5.2.1. Characterization .......................................................................................169

5.2.1.1 Thermal analysis .......................................................................169

5.2.1.2 FTIR spectroscopy ....................................................................174

5.2.2 Casting Studies.........................................................................................174

5.2.2.1 Solution casting of IV-1............................................................174

5.2.2.2 Solution casting of II-5 .............................................................175

5.2.2.3 Blade casting of II-5 .................................................................176

5.2.3 Acid Doping Levels, Thermal Stability and Proton Conductivity of Cast Films ................................................................................................178

5.2.3.1 Acid Doping Levels ..................................................................178

5.2.3.2 Thermal Analysis ......................................................................180

5.2.3.3 Proton Conductivity ..................................................................182

5.3 Conclusion ........................................................................................................183

5.4 Experimental .....................................................................................................183


5.4.2 Preparation of IV-1/KaptonTM Polyimide Blend doped with PPA via Solution Casting .......................................................................................184

5.4.3 Preparation of II-5/KaptonTM Polyimide Composites doped with PPA via

Solution Casting .......................................................................................185

xvi

a). 10II-5/90PI .........................................................................................185

b). 20II-5/80PI .........................................................................................186

5.4.4 Preparation of II-5/KaptonTM Polyimide Composite via Blade Casting .186

5.4.5 Preparation of acid doped II-5/KaptonTM Polyimide Composite ............187

VI. CONCLUDING REMARKS..................................................................................188

BIBLIOGRAPHY .........................................................................................................191

APPENDICES ..............................................................................................................200

APPENDIX A: SUPPLEMENTARY MATERIAL FOR THE X-RAY CRYSTAL STRUCTURE OF C10H10N2O (II-1) .........................................................................201

APPENDIX B: SUPPLEMENTARY MATERIAL FOR THE X-RAY CRYSTAL STRUCTURE OF C9H9N3O (II-2) ............................................................................207

APPENDIX C: SUPPLEMENTARY MATERIAL FOR THE X-RAY CRYSTAL STRUCTURE OF C9H10N4O (II-3a) ........................................................................211

APPENDIX D: SUPPLEMENTARY MATERIAL FOR THE X-RAY CRYSTAL STRUCTURE OF C9H10N4O (II-3b) ........................................................................216

APPENDIX E: SUPPLEMENTARY MATERIAL FOR THE X-RAY CRYSTAL STRUCTURE OF C60H54N15O6P3 (II-4) ...................................................................219

APPENDIX F: SUPPLEMENTARY MATERIAL FOR THE X-RAY CRYSTAL STRUCTURE OF C54H48N21O6P3 (II-5) ...................................................................231

APPENDIX G: SUPPLEMENTARY MATERIAL FOR THE X-RAY CRYSTAL STRUCTURE OF C30H24N9O6P3 (II-7) ....................................................................240

APPENDIX H: SUPPLEMENTARY MATERIAL FOR THE X-RAY CRYSTAL STRUCTURE OF C30H24N9O6P3 (II-8) ....................................................................247

APPENDIX I: SUPPLEMENTARY MATERIAL FOR THE X-RAY CRYSTAL STRUCTURE OF C30H24N9O6P3 (II-9) ....................................................................253

APPENDIX J: ABBREVIATIONS AND ACRONYMS ..........................................258

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LIST OF TABLES

Table Page

1-1. Characteristics of various fuel cell systems .............................................................3

1-2. DOE technical targets for membranes .....................................................................9

1-3. Bond lengths (Å) and bond angles (°) of [PCl2N]n and cyclophosphazenes .........22

1-4. Applications of Polyphosphazenes ........................................................................28

1-5. Comparison of properties of sulfonated I-1, I-2 and commercial cation-exchange membranes ..................................................................................33 1-6. Proton conductivity of 75% SPOP/25% FLEX blended membrane in water ........36

1-7. Comparison of properties of blended and cross-linked SPOP/PAN membranes for DMFCs ...................................................................................................................37

1-8. Membrane properties of selected polymers ...........................................................45

1-9. Proton conductivity of Nafion 117, sulfonated polyphosphazene, phosphonated polyphosphazene at different temperatures ...........................................................45

1-10. Methanol permeability tests...................................................................................46

1-11. Membrane properties of sulfonimide functionalized polyphosphazenes compared to Nafion 117 .........................................................................................49 1-12. Comparison of electrochemical properties of acid functionalized polyphosphazene

with Nafion 117 .....................................................................................................51

1-13. Conductivity of PDPrP.nH+ at 1H3PO4/N mole ratio in PPS net composite at variable temperature and relative humidity (RH, %) .............................................53

1-14. Conductivity of SPHPE-PDPrP-PA under dry conditions and 11% RH at variable temperature ............................................................................................................55

xviii

2-1. 31P NMR chemical shifts of hexakis(azolylmethylphenoxy) cyclotriphosphazenes .............................................................................................73 2-2. 31P NMR Chemical shifts of hexakis(pyridinoxy)cyclotriphosphazenes ..............74

2-3. Inert and air atmosphere TGA parameters of azolylmethylphenoxy and pyridinoxy trimers ....................................................................................................................84 3-1. Molecular weights and its distribution of [P(OCH2CF3)2N]n from the one-pot in situ polycondensation .........................................................................105 3-2. Weight average molecular weights (Mw) and polydispersity indeces (PDI), and

repeat units of [PCl2N]n obtained from GPC .......................................................123

3-3. Inert atmosphere (N2) TGA parameters of phenoxypolymers .............................124

4-1. Synthesis of compound IV-1 ...............................................................................134

4-2. Melt polymerization of pyridinoxytrimers ...........................................................144 4-3. Thermogravimetric parameters of polymers IV-1, IV-2 and IV-3 ......................147

4-4. Degradation temperatures (Td), glass transition temperatures (Tg) and melting temperatures (Tm) of polymers from DSC ...........................................................148

5-1. Different regions of the TGA curve of poly(PMDA-ODA) amic acid ................170

5-2. TGA parameters of IV-1, PI and IV-1/PI ...........................................................175

5-3. TGA parameters of II-5, PI, 10II-5/90PI and 20II-5/80PI ................................176

5-4. TGA parameters of II-5, PI and II-5/PI ..............................................................177

5-5. Acid concentrations used in doping II-5/KaptonTM Polyimide composite ..........178

5-6. Acid doping levels of doped II-5/PI membranes ................................................179

5-7. Inert atmosphere TGA parameters of doped II-5/PI membranes ........................182

xix

LIST OF FIGURES

Figure Page

1.1. A schematic representation of the reactions in a PEMFC (left) and DMFC (right) ....................................................................................................3

1-2. Typical power curve for PEMFC and DMFC..........................................................6

1-3. Schematic of a polymer electrolyte membrane fuel cell (PEMFC) .........................7

1-4. Chemical structures of perfluorinated polymer electrolyte membranes ................10

1-5. Two-dimensional illustration of the nanoscopic hydrated structure of Nafion® ...11

1-6. Proton transfer mechanism in Nafion ® (vehicle mechanism) ...............................12

1-7. Structural formula of most polyphosphazenes and cyclic oligomers (X = F, Cl, Br) ............................................................................14 1-8. Small molecule model compounds of polyphosphazenes .....................................15

1-9. Cis-trans planar conformation of polyphosphazenes ............................................22

1-10. Electron pairing in [PCl2N]3 ..................................................................................23

1-11. Depiction of orbital mismatch in the dπ-pπ bonding structure of [PCl2N]3 ................. 24

1-12. Electron pairing in [PCl2N]n ..................................................................................25

1-13. Depiction of the dπ-pπ bonding in [PCl2N]n ...........................................................25

1-14. Secondary ionic bonds of [PCl2N]3 (left) and [PCl2N]n (right) ..............................26

1-15. Structures of poly(aryloxyphosphazenes). poly[(3- methylphenoxy) phenoxy)phosphazene, I-1: poly[(4-methylphenoxy)(phenoxy)phosphazene, I-2:

poly[(3-ethylphenoxy)(phenoxy)phosphazene, I-3: poly[(4-ethylphenoxy)(phenoxy)phosphazene,I-4 .............................................................31

xx

1-16. Poly[bis(3-methylphenoxy)phosphazene (compound I-5) ....................................34

1-17. Methanol fuel cell performance for blended SPOP/PAN membranes (left) and methanol fuel cell performance with the two-layer and three-layer

SPOP/PAN MEAs (right) ......................................................................................38 1-18. Poly[bis(phenoxy)phosphazene (compound I-6) ...................................................38

1-19. DMFC performance of blended SPOP-PBI membranes with direct electrode attachment (left) and power density dependence on current density for SPOP-PBI

membranes with direct electrode attachment .........................................................39 1-20. Comparison of the temperature dependent conductivities for samples M1 and M2 at high and low water partial pressures (left) and conductivities of various

conducting polymer materials in a water swollen state at 25 °C (right) ................40 1-21. Phosphonic acid functionalized poly(aryloxy)phosphazenes (compounds I-7 and I-8) ........................................................................................42 1-22. Regression curves of conductivity vs. T-1 and activation energies (left) and the selectivity of proton conductive membranes as a function of temperature (right) .............................................................................................46 1-23.Proton transfer via Grotthus mechanism ................................................................52

1-24.Structures of poly(dipropyl)phosphazene (PDPrP) (left) and PPS (right) .............53 1-25.Structure of SPHPE ................................................................................................54

1-26. Log10 σ vs. 1000/T of SPHPE-PDPrP-PA dry ( ) and at 11% RH ( ), and of PPS-PDPrP-PA dry ( ) and at 11% RH ( ) ..................................55 1-27.Poly(diethyl, dipropyl)phosphazene (PDEt, DPrP) ................................................56

1-28.Sulfonated polyimide (SPI) ....................................................................................56

1-29. Log10 σ vs. 1000/T for different N containing materials doped with PA at variable H3PO4/N mole ratio in dry conditions ...................................................................57

1-30. AC conductivity vs. frequency of TriP1TA (left) and ATriP2TA at several temperatures (right) ................................................................................................59

1-31. Variation of the proton conductivity of the TriP (left) and ATri (right) with various TA concentrations as a function of reciprocal temperature ......................59 2-1. Structures of compounds II-1, II-2 and II-3 .........................................................64

xxi

2-2. Thermal ellipsoid plots of the crystal structures of II-1 (left) and II-2 (right). Thermal ellipsoids are drawn at 50% probability ..................................................66

2-3. Thermal ellipsoid plots of the crystal structures of II-3a (left) and II-3 (right).

Thermal ellipsoids are drawn at 50% probability ..................................................66

2-4. 1H NMR spectrum of a mixture of compounds II-3a and II-3b in d6-DMSO ......67 2-5. 1H NMR spectrum of compound II-2 in d6-DMSO...............................................71

2-6. 1H NMR spectrum of compound II-5 in d6-DMSO...............................................72

2-7. 31P NMR spectra showing the chemical shift variation of [PCl2N]3 in (CDCl3), compound II-4 (d6-DMSO), compound II-5 (d6-DMSO), and compound II-6 (d6-DMSO) ...................................................................................73 2-8. 31P NMR spectra showing the chemical shift variation of [PCl2N]3 in (CDCl3),

compound II-7 (d6-DMSO), compound II-8 (d6-DMSO), and compound II-9 (d6-DMSO) ...................................................................................75 2-9. Thermal ellipsoid plot of the crystal structure of II-4. Thermal ellipsoids are drawn

at 50% probability ..................................................................................................76

2-10. Thermal ellipsoid plot of the crystal structure of II-5. Thermal ellipsoids are drawn at 50% probability ..................................................................................................76

2-11. Thermal ellipsoid plot of the crystal structure of II-7. Thermal ellipsoids are drawn

at 50% probability ..................................................................................................77 2-12. Thermal ellipsoid plot of the crystal structure of II-8. Thermal ellipsoids are drawn

at 50% probability ..................................................................................................78 2-13. Thermal ellipsoid plot of the crystal structure of II-9. Thermal ellipsoids are drawn

at 50% probability ..................................................................................................78 2-14. Inert atmosphere thermogravimetric analysis of azolylmethylphenoxy and pyridinoxy trimers ..................................................................................................81 2-15.Air atmosphere thermogravimetric analysis of azolylphenoxy and pyridinoxy

trimers ....................................................................................................................82 2-16.Inert atmosphere thermogram and derivatogram of compound II-6 ......................82 2-17.Inert atmosphere thermogram and derivatogram of compound II-8 ......................83

xxii

2-18. Inert atmosphere thermogram and derivatogram of compound II-7 .....................83 3-1. Variation in the yield (solid line) and intrinsic viscosity (broken line) of [PCl2N]n as a function of water concentration after polymerization of [PCl2N]3 after 15 hrs at 250 °C ................................................................................................................99 3-2. 31P NMR spectra showing the compound III-1a in CDCl3 (a) sampling after stirring at RT for overnight, (b) after heating at 110 °C for a day, (c) hexane

purified polymer ..................................................................................................................................................... 109 3-3. 31P NMR spectra of compound III-1b in CDCl3 (a) sampling after breaking the tube (b) after vacuum sublimation (c) purification into hexane, (d) polymer

completely purified by hexane .............................................................................112 3-4. Expanded 31P NMR spectrum shown in Figure 3-3(a). ........................................113 3-5. ESI mass spectrum of [PCl2N]n purchased from Aldrich ...................................... 116 3-6. ESI-Q/ToF MS of compound III-1a....................................................................117 3-7. Inset of the ESI-Q/ToF mass spectrum of compound III-1a from 800-1120 m/z .......................................................................................................117 3-8. Suggested tadpole structure of the chlopolymer ..................................................118 3-9. Isotopic distribution of compound III-1a ............................................................118 3-10. (a) 31P NMR of compound III-1a (-17.8 ppm), (b) 31P NMR of compound III-2a (-19.3 ppm) in CDCl3 ......................................................................................................................................... 120 3-11. 1H NMR (top left) and 31P NMR (bottom right) of compound III-2b in CDCl3 ...................................................................................................................................................................... 120 3-12. MALDI-ToF spectrum of compound III-2a .......................................................121 3-13. MALDI-ToF spectrum of compound III-2b .......................................................122 3-14. Inert atmosphere (N2) thermograms of compounds III-2a and III-2b ...............125 4-1. 31P NMR spectrum of compound IV-1 in d6-DMSO ...........................................135 4-2. 1H NMR spectrum of compound IV-1 in d6-DMSO ...........................................136 4-3. MALDI-ToF spectrum of compound IV-1 showing the repeat unit of PN7C18O2H16 ....................................................................................................137

xxiii

4-4. 31P NMR spectrum of compound IV-2 in d6-DMSO ...........................................138

4-5. 1H NMR spectrum of compound IV-2 in d6-DMSO ...........................................139

4-6. 13C NMR spectrum of compound IV-2 in d6-DMSO ..........................................139

4-7. MALDI-ToF spectrum of compound IV-2 showing the repeat unit of PN9C18O2H18 ....................................................................................................140

4-8. 31P NMR of compound IV-3 in d6-DMSO ..........................................................142

4-9. 1H NMR of compound IV-3 in d6-DMSO ...........................................................142

4-10. MALDI-ToF spectrum of compound IV-3 showing the repeat unit of PN3C10O2H8 .....................................................................................................143 4-11. Structures of pyridinoxytrimers ...........................................................................144

4-12. 31P NMR spectra after direct melt polymerization reaction of II-7 (at 200 °C for 12 h) (a), and II-9 (at 170 °C for 30 min) (b) ...............................................145 4-13. Inert atmosphere thermograms of polymers IV-1, IV-2 and IV-3 ......................146 4-14. Air atmosphere thermograms of polymers IV-1, IV-2 and IV-3 ........................147 4-15. DSC thermograms of polymers IV-1, IV-2 and IV-3 .........................................148

5-1. Intermolecular proton transfer between neighboring protonated and unprotonated triazoles ................................................................................................................155

5-2. Imidazole functionalized systems (Imi-x: x = 2-5) ..............................................156 5-3. Imidazole bound to polystyrene via flexible spacers ...........................................157 5-4. Structure of P-4VI ................................................................................................157 5-5. Structure of PVPA ................................................................................................158 5-6. Structures of PSSA (left) and imi3 (right) ...........................................................158 5-7. Chemical structures of MDP (left) and BnIm (right) ...........................................159 5-8. Structures of polybenzimidazole, PBI (left) and poly(2,5-benzimidazole), ABPBI

(right) ...................................................................................................................159

xxiv

5-9. Structure of PAMPS ............................................................................................160 5-10. Structures of PGMA-ATri (left) and PGMA-Tri (right) .....................................161 5-11. Structure of PGMAATet .....................................................................................162 5-12. Structures of P2VP (left) and P4VP (right) .........................................................162

5-13. KaptonTM polyimide ............................................................................................163

5-14. Inert atmosphere thermogram and derivatogram of poly(PMDA-ODA) amic acid .............................................................................170 5-15. Inert atmosphere thermogram and derivatogram of poly(PMDA-ODA) imide ...................................................................................171 5-16. FTIR spectra (absorbance mode) of PAA and PI after imidization at 200 °C for 1, 2, 3 and 12 hours ........................................................................................173 5-17. IV-1/ KaptonTM polyimide blend ........................................................................174

5-18. Inert atmosphere thermograms of IV-1, PI and IV-1/PI .....................................174

5-19. II-5/KaptonTM polyimide composite 10 wt% (left) and 20 wt% (right) from solution casting ....................................................................................................175

5-20. Inert atmosphere thermograms of II-5, PI, 10II-5/90PI and 20II-5/80PI .........176

5-21. II-5/KaptonTM polyimide composite from blade casting ....................................177

5-22. Inert atmosphere thermograms of PI, II-5/PI and II-5 .......................................177

5-23. Inert atmosphere thermograms of undoped and H3PO4 doped II-5/PI membranes ...........................................................................................................181 5-24. Inert atmosphere thermograms of undoped and H2SO4 doped II-5/PI membranes ...........................................................................................................181 5-25. Inert atmosphere thermograms of undoped and HNO3 doped II-5/PI membranes ...........................................................................................................181

xxv

LIST OF SCHEMES

Scheme Page

1-1. Synthesis of hexachlorocyclotriphosphazene-[PCl2N]3 ........................................16

1-2. Ring opening polymerization of [PCl2N]3 to [PCl2N]n ..........................................17

1-3. Synthesis of [PCl2N]n from PCl5 and NH4Cl in solution state using 1,2,4-chlorobenzene ........................................................................................................18

1-4. Synthesis of [PCl2N]n from PCl5 and (NH4)2SO4 in solid state ..............................18

1-5. Synthesis of [PCl2N]n from Cl3P=NP(O)Cl2 ........................................................................................ 19

1-6. Living cationic polycondensation of Cl3P=NSiMe3 ...................................................................... 19

1-7. Functionalization of polyphosphazenes via primary macromolecular substitution .............................................................................................................20 1-8. Nucleophilic substitution (Nu- = -OR) via an SN2 mechanism ..............................21

1-9. The reaction scheme for polyphosphazene sulfonation with SO3 ....................................... 32

1-10. Phosphonation of poly(aryloxy)phosphazenes bearing bromomethylene-phenoxy side groups .............................................................................................................42 1-11. Phosphonation of poly(aryloxy)phosphazenes via lithiophenoxy side groups. I-8* is analogous to polymer I-7b, however the methyl groups are in the 3-position rather than the 4-position ......................................................................43 1-12. Synthesis of aryl sulfonimide side group ...............................................................47

1-13. Synthesis of sulfonimide functionalized polyphosphazenes ..................................48

1-14. Synthesis of perfluorobutylsulfonylimide functionalized polyphosphazenes .......50

1-15. Synthesis pathway of TriP and ATriP starting from [PCl2N]n ..............................58

xxvi

2-1. Condensation reaction between azole and 4-hydroxybenzylalcohol to obtain compounds II-1, II-2 and II-3 ...............................................................................64

2-2. Proposed mechanism of the synthesis of compounds II-3a and II-3b ..................65

2-3. General synthetic route of hexakis(azolylmethylphenoxy)cyclotriphosphazenes .69

2-4. Synthesis of compounds II-7, II-8 and II-9 from the pyridinols ..........................74

3-1. Ring opening polymerization of [PCl2N]3 to [PCl2N]n ..........................................97

3-2. The depolymerization of [PCl2N]n above 350 °C ..................................................98

3-3. Mechanism of ROP of [PCl2N]3 by Emsley ........................................................100

3-4. Mechanism of ROP of [PCl2N]3 by Allcock........................................................101

3-5. Mechanism of polycondensation .........................................................................103

3-6. Overall synthesis of compound III-1a .................................................................107

3-7. Overall process of ROP (compound III-1b) ........................................................115

3-8. Synthesis of P(OC6H5)2N]n (compound III-2) ....................................................119

4-1. Synthesis of [PR2N]n ............................................................................................131




5-1. General synthetic scheme of PAA .......................................................................164

5-2. Conversion of PAA into polyimide .....................................................................165

5-3. Synthesis of KaptonTM polyimide via two-step thermal imidization ...................165

xxvii

LIST OF EQUATIONS

Equation Page

1-1 .....................................................................................................................................4

1-2 .....................................................................................................................................4

1-3 .....................................................................................................................................4

1-4 .....................................................................................................................................4

1-5 .....................................................................................................................................4

1-6 .....................................................................................................................................4

1-7 .....................................................................................................................................4

1-8 .....................................................................................................................................4

1-9 ...................................................................................................................................15

2-1 ...................................................................................................................................68

2-2 ...................................................................................................................................68

1

CHAPTER I

INTRODUCTION TO POLYPHOSPHAZENE BASED PROTON EXCHANGE

MEMBRANES FOR FUEL CELLS

1.1 Introduction to Fuel Cells

The combustion of fossil fuels is currently seen as the most important way of

meeting the demand for energy, which has been rising at a rapid rate over the past few

decades. Despite the favorable effects, combustion of fossil fuels also leads to air

pollution due to the increased concentration of carbon dioxide, which is one of the major

emissions resulting from the combustion of fossil fuels. Among other significant factors

that propel the need for alternative sources of energy are the gradual depletion of the

limited fossil fuel reserves available and the desire to reduce the dependence on foreign

oil.1, 2 Due to these reasons, electrochemical energy production has been under serious

consideration for some years as an alternative to fossil fuel combustion.3 In this context,

fuel cells have become one of the most promising technologies which use non-fossil fuel

sources like hydrogen.4-7

A fuel cell is an electrochemical energy conversion device that directly converts

chemical energy into electrical energy via an electrochemical reaction of fuels and

oxygen.3,8 Even though the invention of the first fuel cell goes back to the mid-19th

century, there were not applications up until the 1960’s when NASA introduced the

2

fuel cell to the Gemini space project. Today, the most promising commercial applications

of fuel cells are as a stationary power source and as a mobile power source for portable

electronic devices and automobiles.3

1.1.1 Types of Fuel Cells

Fuel cells are open systems that consist of an anode and a cathode.3 A most

critical part of a fuel cell is its separator material—the electrolyte—conducting

preferentially one kind of ion but impervious to electrons.3,5 Although both fuel cells and

batteries are systems for electrochemical energy storage and conversion, fuel cells differ

from batteries in that the fuel and oxidant are not contained within the fuel cell but

supplied continuously through an external source. Therefore, energy storage and energy

conversion are locally separated.3

There are two different ways of categorizing fuel cells. In one of them, fuel cells

are roughly divided into two different types, based on their operating temperature; low-

temperature (ca. < 200 °C) and high-temperature (ca. > 450 °C) fuel cells. But typically,

there are five different types of fuel cells that are classified by the type of electrolyte

being utilized, irrespective of their similarity in function.3 Table 1-1 summarizes some of

the key characteristics of those fuel cell systems, including type of electrolyte and

operating temperature.3,8

1

ce

ac

th

an

th

F(r

.1.2 Fuel Ce

The m

ells (PEMFC

cidic polyme

hat could be

nd kinetics f

hat occur in b

igure 1-1. Aright).8

Type of FueAlkaline (AFProton ExchDirect MethPhosphoric AMolten CarbSolid Oxide

Table 1-1. C

ell Operation

main focus of

Cs) and direc

er electrolyte

used in both

for electroch

both of those

A schematic r

el CellFC)hange Membrhanol (DMFC)Acid ( PAFCbonate (MCFC(SOFC)

Characteristi

n (PEMFCs a

f this section

ct methanol

e, and our re

h of them. Bo

hemical syste

e cells are il

representatio

rane (PEMFC)

C)C)

3

ics of variou

and DMFCs

n will be on t

fuel cells (D

esearch focu

oth types of

ems.3 A sche

lustrated in F

on of the rea

Electrolyteaq KOH

C) acidic polyacidic polyphosphoricmolten Li2yttria-stabstabilized z

us fuel cell sy

)

the proton e

DMFCs) beca

s is also on s

f fuel cells fo

ematic repres

Figure 1-1.

actions in a P

e

ymerymerc acid in SiC m2CO3 in LiAlObilized or yttriazirconia suppo

ystems.3,8

exchange me

ause they bo

synthesizing

ollow the the

sentation of

PEMFC (left

Tem60 80 80

matrix 160O2 600a/calcia- 800ort

embrane fuel

oth use the sa

g an electroly

ermodynami

the reaction

t) and DMFC

mperature (°C- 90 - 110 - 110

0 - 2000 - 8000 - 1000

l

ame

yte

cs

ns

C

C)

4

Proton exchange membrane fuel cells (PEMFCs) are also called polymer

electrolyte fuel cells (PEFCs) or solid polymer electrolyte fuel cells (SPEFCs) because

they utilize a solid proton conducting polymer as the electrolyte. Usually both PEMFCs

and DMFCs are low-temperature operating fuel cells. PEMFC was first developed for the

Gemini space vehicle, and later, they have been used in notebook computers, power

sources in vehicles, and in power generators, due to their reduced size and low weight.

PEMFCs utilize hydrogen gas as fuel whereas oxygen is fed as the oxidant. Therefore, for

a H2/O2 fuel cell, the electrode reactions can be written as follows,

Anode: H2 – 2e = 2H+ (1-1)

Cathode: O2 + 2H+ + 2e = H2O2 (1-2)

H2O2 + 2H+ + 2e = 2H2O (1-3)

Overall cathode reaction: O2 + 4H+ + 4e = 2H2O (1-4)

Overall cell reaction: H2 + 1/2O2 = H2O (1-5)

For this reaction, ΔG° is -235.76 KJ/mol whereas ΔH° is found to be -285.15 KJ/mol.

Direct methanol fuel cells (DMFCs) also have the same polymer electrolyte

membrane, but different fuel resources. Instead of hydrogen gas as fuel, it utilizes pure

methanol or methanol-water mixture. Due to their compact size, they are used as batteries

in electronic equipments such as laptop computers and mobile phones. Equations 1-6 to

1-8 illustrate the electrochemical reactions occur in a DMFC.

Overall cell reaction: CH3OH + 3/2O2 = CO2 + 2H2O (1-6)

Anode: CH3OH + H2O - 6e = 6H+ + CO2 (1-7)

Cathode: O2 + 4H+ + 4e = 2H2O (1-8)

5

Although the type of fuel is different in the two cells, the oxidation of the fuel

produces protons on the anode, and they travel through the proton exchange membrane

(PEM) to the cathode as shown in Figure 1-1. At the cathode, oxygen is fed into both

cells, and then it starts undergoing reduction to produce water. As a result of this proton

conduction through the membrane, an electric current is produced.3

Because both types of cells utilize oxygen as the oxidant, another common feature

for both cells is the two-step indirect reduction of oxygen where the intermediate, H2O2 is

formed (eqs 1-2 and 1-3). This is an undesirable species because it lowers the cell voltage

and attacks the carbonaceous electrode material and corrodes it. One of the ways to tackle

this problem is by plating Pt as a catalyst which increases the decomposition of H2O2 and

thereby reduces the impact on overall cell reaction. Pt not only increases the

decomposition of H2O2 but also speeds the reactions on both electrodes in low-

temperature PEMFCs. In order to suppress this two-step oxygen reduction, it is necessary

to have a high amount of catalyst loading. Due to high cost of Pt, current research has

focused more on reducing the catalyst loading. Because PEMFC is a low-temperature

functioning fuel cell, hydrogen gas has become the preferred fuel, although it is not

readily available. In order to use hydrocarbon fuels—such as methane or gasoline like in

other high temperature fuel cells—they must first be converted into hydrogen.3

p

7

co

cu

ac

on

to

(P

(~

fu

Figuermission of

Fuel c

0%. This va

onsidered. T

urve shown

ccording to t

As sho

n either side

o serve as a p

Pt/C) has bee

~0.1 mg/cm2

unctions as a

ure 1-2. Typf The Ameri

cells can ope

lue can be ra

The performa

in Figure 1-

this curve, th

own in Figu

e of the elect

plenum for t

en applied to

2) than that o

a gas transpo

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erate with rea

aised up to 9

ance of the fu

2. Although

he operating

ure 1-3, in a P

trolyte. A gra

the gas suppl

o the membr

of the cathod

orter to the re

6

curve for PEMal Society.3

ally high ele

90% if the w

fuel cell is no

the theoreti

g voltage is lo

PEMFC, two

aphite or me

ly and for he

rane surface.

de (0.5 mg/cm

eaction zone

MFC and D

ectrical effici

waste heat of

ormally mon

ical voltage o

ower than th

o electrodes

etal plate is p

eat removal.

. The anode

m2). The gas

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MFC. Repro

iencies in th

the fuel cell

nitored by th

of the fuel ce

hat.3

are formed

placed next t

A catalyzed

has a lower

s diffusion la

oduced by

he range of 6

l is also

he voltage-cu

ell is 1.23 V

on a thin lay

to each elect

d carbon laye

catalyst load

ayer (GDL)

0-

urrent

V,

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R

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F

fo

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v

p

Figure 1-3.Reproduced b

One o

uel system o

s contaminat

perating fue

he Pt catalys

ower.8,9

DMFC

igure 1-3. H

ormation of

hese cells is

lectrolyte du

oltage and th

ossibility in

. Schematic by permissio

of the major

nly consists

ted mainly w

l cells. CO p

ts which blo

Cs also use t

Here Pt/Ru ca

a stable form

the methano

ue to its solub

he overall ef

minimizing

of a polymeon of The Am

obstacles esp

of pure fuel

with CO. Thi

poisoning ha

ocks the reac

the same bas

atalyst is use

mic acid inte

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bility. On ca

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this effect. O

7

er electrolytemerican Che

pecially in P

l. But in the

is is a charac

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ction with th

sic cell const

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ermediate du

from anode

athode, it und

the cell.3 Sev

One solution

e membrane emical Socie

PEMFCs is t

majority of

cteristic featu

o adsorption

he fuel and th

truction as fo

compared to

uring oxidatio

side to the c

dergoes oxid

veral studies

n is to use a

fuel cell (PEty.3

the CO poiso

real systems

ure of low-te

n of CO on th

hereby reduc

for the PEMF

o PEMFC to

on. The maj

cathode side

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thicker mem

EMFC).

oning. Ideall

s, H2 fuel str

emperature

he active site

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FC as shown

o avoid the

or obstacle i

through the

cing cathode

ed out to see

mbrane like

ly, a

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es of

n in

in

the

8

Nafion®120 or doping the membrane with Cs+ ions, and another approach is the

development of methanol tolerant cathodes.8

It is obvious that the electrolyte plays a major role in the outcome of the fuel cell,

depending on its properties. Therefore, a detailed review on PEMs will be discussed in

section 1.2.

1.2 Proton Exchange Membranes/Polymer Electrolyte Membranes (PEMs)

The development of PEMs has become a challenge due to the necessity of

simultaneously balancing properties such as conductivity, chemical stability, mechanical

stability, durability and cost.10 It has been found that in order to be a high performing

proton exchange membrane, the polymeric material has to meet a few requirements,

including: 1) low cost, 2) high proton conductivities, 3) low permeability to fuel and

oxidant, 4) low water transport through diffusion and electro-osmosis,

5) oxidative and hydrolytic stability, 6) good mechanical properties, 7) low electronic

conductivity, and 8) capability for fabrication into membrane electrode assemblies

(MEAs).4,6 Over the past years, several different types of proton conducting membranes

have been developed targeting higher conductivities both in PEMFCs and DMFCs. Of

them, two major challenges in the advancement of fuel technology are cost and durability

of PEMs used in fuel cells. Because most of the PEMs currently available depend on the

presence of water to conduct the protons, the fuel cells have a limited operating

temperature. To address these challenges, in 2006 U.S. Department of Energy (USDOE)

put forward twelve new technical targets for the years 2010 and 2015 that were aimed at

developing PEMs that would operate at high temperature and low relative humidity.

9

According to that, 2015 targets include conductivity of PEMs to be 0.1 S cm-1 at 120 °C

and 1.5 kPa inlet water vapor partial pressure at 50% RH at room temperature.10

Table 1-2. DOE technical targets for membranes.10

It has always been difficult to integrate all of those properties into a single

membrane for their optimum performance. Because most of the currently available

membranes depend on humidification for high proton conductivity, current research is

more focused on making membranes which can operate at high temperatures (up to

120 °C) and at lower relative humidity to meet the DOE targets mentioned above.

Thereby it will eliminate the complexities that arise by thermal and water management

requirements, which in turn causes an increase in the weight and volume of the fuel

cell.10 It could also benefit PEMFC performance in terms of CO tolerance and faster

electrode kinetics as well as residual heat management.9

1.2.1. Types of PEMs

1.2.1.1 Perfluorinated Polymer Electrolytes

Perfluorinated polymer electrolytes are seen as the most promising electrolyte

membranes, and they have been the most widely studied polymeric membranes for fuel

cells.10-12 These include Nafion®, Aciplex®, Flemion®, and Dow membranes.12 These

Characteristic Units 2010 target 2015 targetOperating temperature °C < 120 < 120Inlet water vapor partial pressure kPa < 1.5 <1.5Membrane conductivity S cm-1 0.1 0.1Cost $ m-2 20 20Durability h 2000 5000

10

polymers are generated by copolymerization of a perfluorinated vinyl ether comonomer

with tetrafluoroethylene (TFE).13 The fluorinated backbone provides good thermal,

chemical, and mechanical properties other than the high degree of proton conductivity

under high humidity conditions.11,12

Nafion® 117 m≥1, n=2, x=5-13.5, y=1 Flemion® m=0, 1; n=1-5 Aciplex® m=0, 3; n=2-5, x=1.5-14 Dow membrane m=0, n=2, x=3.6-10 Figure 1-4. Chemical structures of perfluorinated polymer electrolyte membranes.12

Nafion®

Of the four different types of perfluorinated polymer electrolytes available,

Nafion® has been the most common PEM employed in fuel cells due to its high

conductivity and outstanding chemical stability combined with longevity of 60,000 hours

at 80 °C.12,14 After Nafion® was developed in 1968 by Dupont, its first commercial

application was in Biosatellite spacecraft in 1969. This is commercially available in 900,

1100, 1200, and other equivalent weights (EW). However, Nafion 1100 EW in

thicknesses of 2, 5, 7, and 10 mil with resulting Nafions of 112, 115, 117, and 1110

respectively, seem to be the only grades that are currently widely available.13

F2C

F2C

F2C

FC

OF2C CF

CF3

Om

CF2 SO3Hn

x y

hy

m

co

in

sc

in

A

p

g

hy

FR

Nafion

ydrophilic (s

membrane its

onduction of

nvestigated t

cattering (SA

ntermediate w

According to

ockets. Mor

ood connect

ydrophilic-h

igure 1-5. TReproduced b

n® consists o

sulfonic acid

s morpholog

f protons onc

through sma

ANS) experi

water conten

this model,

eover, the pe

tivity, and th

hydrophobic

wo-dimensioby permissio

of interpenet

d groups) do

ical stability

ce it is hydra

ll-angle X-ra

iments. Figur

nt, based on

Nafion® has

ercolated hy

here are almo

interface an

onal illustraton of The Am

11

trating hydro

omains in wh

y whereas hy

ated. The mi

ay scattering

re 1-5 depic

the SAXS st

s wide water

ydration struc

ost no dead e

nd less inter-

tion of the nmerican Che

ophobic (pol

hich hydroph

ydrophilic do

icrostructure

g (SAXS) an

ts the nanos

tudies of Ge

r channels an

cture of Nafi

end channels

sulfonate gr

nanoscopic hemical Socie

lymer backb

hobic domain

omain facilit

e of Nafion®

nd small-ang

copic view o

ebel and co-w

nd more sep

fion® is less b

s. Further, th

roup separati

hydrated struety. 15

bone) and

n gives the

tates the

® has been

gle neutron

of Nafion® f

workers.

arated hydra

branched wit

here is only l

ion.13,15

ucture of Naf

for an

ation

th

less

fion®.

12

The proton transport mechanism of Nafion® was investigated by Kreuer.15 The

mechanism of proton conduction along the perfluorosulfonated membrane occurs through

the vehicular mechanism as shown in Figure 1-6, and this is a matrix assisted transport

and the proton diffuses together with a vehicle (as H3O+) where the counter diffusion of

unprotonated vehicles (H2O) allows the net transport of protons.16,17 Because this depends

on the presence of water to ferry the protons, as the temperature increases, conductivity

slightly increases and then decreases at higher temperature as the water content decreases

due to evaporation.10 The conductivity of Nafion® reaches up to 10-2-10-1 S cm-1 in its

fully hydrated state. But it gradually decreases as the temperature increases above 100

°C.12

Figure 1-6. Proton transfer mechanism in Nafion ® (vehicle mechanism). 17-19

1.2.1.2 Alternative Polymer Electrolyte Membranes

The proton conductivity of Nafion® depends on the presence of water. As a result,

its use is limited to operating temperatures of 60-80 °C, and it requires external

humidification to maintain optimum performance. Therefore, these fluorinated

membranes have a few major drawbacks that slow down their widespread industrial

application. Among these drawbacks are high material cost (US$ 700 per square meter),

durability of membranes and low conductivity at high temperatures and low humidities as

+ ++

+ ++

+ +++

+ +

13

well as complex external humidification.9-15 To overcome these problems, different

approaches have been used to modify Nafion® to obtain composite structures by

incorporating various inorganic proton conductors into the membranes such as silicon

dioxide (Aerosol®)20,21 and molybdophosphoric acid,21 followed by the replacement of

the sulfonic acid functional units of Nafion® with bis[(perfluoroalkyl)sulfonyl]imide

units.22 Consequently, physical and electrochemical properties can be improved for better

performance.4,9,12,13,15

Moreover, many other non-fluorinated hydrocarbon based polymeric membranes

have been studied as alternatives to Nafion® .9,12

These include sulfonated polyimides

(SPI),12,23-25 sulfonated aromatic polymers such as sulfonated poly(ether ether ketone)-S-

PEEK,12,26-30 alkylsulfonated aromatic polymers such as polybenzimidazoles (PBI)9,12,30-33

and acid-base polymer complexes where basic polymers such as poly(ethylene oxide)-

PEO and polyethyleimine-PEI are incorporated with acids such as H3PO4.12,34-36 Also,

inorganic polymers such as polyphosphazenes were studied extensively in this regard as

another alternative.

Of all those alternative polymer electrolyte membranes, the following review will

be completely on PEMS based on phosphazene polymers because our research focus is

also on the same. Before reviewing all the available membranes based on phosphazene

polymers, the background information on polyphosphazenes (Section 1.3) and their small

molecule model compounds, cyclophosphazenes (Section 1.3.1), polymerization methods

(Section 1.3.2), macromolecular substitutions (Section 1.3.3), bond lengths and bond

angles in cyclo and polyphosphazenes (Section 1.3.4) and finally applications of

polyphosphazenes (Section 1.3.5) will be reviewed briefly.

14

1.3 Polyphosphazenes

Polyphosphazenes are a class of inorganic polymers with an alternating

phosphorus and nitrogen backbone which is stable to electrochemical oxidation and

reduction. The most intriguing feature about polyphosphazenes is the ease of attaching

organic, organometallic, or inorganic units to the backbone, giving rise to vast amounts of

polymers.37-39 Figure 1-7 shows the structure of this polymer.

Figure 1-7. Structural formula of most polyphosphazenes and cyclic oligomers (X = F, Cl, Br).

Although polyphosphazenes are available in all three fluoro, chloro and bromo

derivatives, the main focus has been steered towards chloropolymer – [PCl2N]n. The

bromopolymer has played only an insignificant role in phosphazene chemistry owing to

its high sensitivity towards cross-linking.40 Although fluoropolymer comes next to

chloropolymer, its applications are limited due to its poor solubility in almost all

solvents.40,41

[PCl2N]n is very reactive due to the presence of very polar P-Cl bonds that lead to

the degradation of this unsubstituted polymer in the atmosphere by hydrolysis to give

phosphate, hydrogen chloride and ammonia during several days of exposure (eq 1-9).41

This same high reactivity makes them ideal intermediates for macromolecular

substitution that not only gives stability to polymer but also delivers very important

properties,41 which will be discussed in section 1.3.5.

P NX

Xn

15

[PNCl2]n PO43- + HCl + NH3 (1-9)

As discussed above, to understand the structure and reactions of these

macromolecules, the small molecule precursors of high polymers have been utilized as a

tool due to the complexity of macromolecules. The section 1.3.1 will review this small

molecule model concept.

1.3.1 Small-Molecule Model Compounds for Polyphosphazenes

Phosphazene macromolecules are inherently more difficult to synthesize, modify

by chemical reactions, purify and characterize than most of other small molecule

compounds. One of the solutions extensively utilized therefore in phosphazene chemistry

are small-molecule “model” systems as synthetic, mechanistic, or structural substitutes

for those high polymers. These small molecules can be easily synthesized, purified and

readily characterized in contrast to their high polymers. The information derived from the

most successful model compound experiments can then be applied to their high polymer

systems.42 There are basically three different types of model compounds as illustrated in

Figure 1-8.

[PX2N]3 [PX2N]4 [PX2N]m

cyclic trimer cyclic tetramer linear short chain

X = halogen or organic group

Figure 1-8. Small-molecule model compounds of polyphosphazenes.42

P N PNPNP

N

XX

XX

XX

XX

NP

NPN

PXX

X X

XX

P N PNX

XPX

XX

X

XO

x

H2O

16

Of the three, cyclic trimers have been the most studied model compounds due to their

ease of synthesis and availability in high quantities.42 Scheme 1-1 depicts the synthetic

route of cyclic trimer in which PCl5 is reacted together with NH4Cl. This reaction was

used to carry out in refluxing sym-tetrachloroethane until the 1970s. But sym-

tetrachloroethane was later replaced with chlorobenzene or o-dichlorobenzene due to its

toxicity.40

Scheme 1-1. Synthesis of hexachlorocyclotriphosphazene-[PCl2N]340

But there are limitations of this model compound approach because cyclic trimers

are not ideal models for several reasons: 1) ring is planar and rigid whereas the polymer

backbone is linear and flexible, 2) side groups in trimers are oriented away from each

other whereas in the polymers, the side groups on adjacent repeating units come close

together, and 3) thermal studies based on cyclic trimers tend to underestimate the

complexicity of the thermal behavior of polymers because the cyclic trimer is

thermodynamically more stable than linear high polymers.42

NP

NPN

PClCl

Cl Cl

ClClP N P

NPNP

N

ClCl

ClCl

ClCl

ClCl

+ + Higher cyclic and linear oligomers

40 – 60% 30% 20 - 30%

PCl5 + NH4Clchlorobenzene

17

1.3.2 Polymerization Methods

Since Stokes’ attempt to synthesize polyphosphazenes in 1897 to the mid 1960s,

the synthetic development of phosphazene field was almost untouched due to their

reported insolubility.43 Stokes isolated an elastomeric rubbery material by heating the

small molecule monomer, [PCl2N]3. He found that the rubbery material to be insoluble in

all solvents, and those insoluble cross-links were later called “inorganic rubber”.43,44

[PCl2N]n synthesis has been an area of interest for many main group scientists, due to the

vast area of applications.

A. Ring opening polymerization (ROP)

After a few failures, Allcock and co-workers found the best method to prepare the

soluble polymer [PCl2N]n was via thermal ring opening, with careful control of

temperature and time, in contrast to Stokes’ method.43 A detailed review on ROP will be

discussed in Chapter III.

Scheme 1-2. Ring opening polymerization of [PCl2N]3 to [PCl2N]n43

B. Condensation Polymerization

As the phosphazene research area broadened, researchers also became interested

in alternative methods for polymer synthesis in order to overcome the drawbacks inherent

P NCl

Cln

NP

NPN

PClCl

Cl Cl

ClCl250 °C

18

in ROP. As a result, alternative methods based on condensation polymerization started to

evolve.

a. Condensation of PCl5 with Ammonium Chloride

Carriedo and co-workers carried out the synthesis of [PCl2N]n from the direct

condensation between PCl5 and NH4Cl. This was a known route to phosphazene small

molecules (n = 3, 4, 5 and so on).45 In the reaction as shown in Scheme 1-3, HSO3(NH2)

was used as a catalyst whereas CaSO4.2H2O was used as a promoter in the solution state.

The yield of polymer was about 30% based on PCl5.

Scheme 1-3. Synthesis of [PCl2N]n from PCl5 and NH4Cl in solution state using 1,2,4-chlorobenzene45

b. Condensation of PCl5 and Ammonium Sulfate

Allen and co-workers came up with a synthetic route to [PCl2N]n with the use of

PCl5 and (NH4)2SO4 in solid state as shown in Scheme 1-4. This was carried out as a one-

pot two-step synthesis. In the first step, two reactants (9:2) were heated at 165 °C to

obtain the phosphoranimine monomer followed by the polycondensation to [PCl2N]n with

the loss of P(O)Cl3. The yield of polymer was 100% based on (NH4)2SO4.46

Scheme 1-4. Synthesis of [PCl2N]n from PCl5 and (NH4)2SO4 in solid state46

PCl5 + NH4Cl P NCl

Cln

HSO3(NH2)

CaSO4.2H2O Reflux

PCl5 + NH4(SO4)2 Cl3P=NP(O)Cl2165 °C 225 °C

P NCl

Cln

-POCl3

19

c. Condensation of Cl3P=NP(O)Cl2

De Jaeger and co-workers have shown that the phosphoranimine Cl3P=NP(O)Cl2

undergoes polycondensation at 240 °C to 290 °C at atmospheric pressure with loss of

P(O)Cl3 to yield polyphosphazene. The reaction is shown in Scheme 1-5 and can be

carried out in both bulk and solution. Polymers of molecular weight of 600,000 Da were

obtainable, although they had a broad polydispersity (1.7).47,48

Scheme 1-5. Synthesis of [PCl2N]n from Cl3P=NP(O)Cl247,48

d. Living Cationic Condensation Polymerization

This polymerization was developed by Allcock and co-workers in the 1990s in

which a phosphoranimine Cl3P=NSiMe3 was polymerized in the presence of a trace

amount of PCl5.48 A detailed review of this condensation polymerization will be

discussed in Chapter III.

Scheme 1-6. Living cationic polycondensation of Cl3P=NSiMe348

1.3.3 Macromolecular Substitution

Macromolecular substitution is the key process in synthesizing hundreds of

different polymers, starting from hydrolytically unstable polyphosphazene. Scheme 1-7 is

Cl3P=NP(O)Cl2Cl3P=N P N P(O)Cl2

Cl

Cl n

‐P(O)Cl3

Cl3P=NPSiMe3 P NCl

Cln

Trace PCl525 °Csolvent

20

a depiction of the substitutions with alkoxide and aryloxide, amines (primary or

secondary) and organometallic reagents, respectively.41

Scheme 1-7. Functionalization of polyphosphazenes via primary macromolecular substitution41

The halogen replacement takes place via nucleophilic substitution in which the

incoming nucleophile attacks the phosphorus on phosphazene and displaces the

chloride.41 These substitutions could follow the SN1 or SN2 type substitutions similar to

those in organic chemistry. Although the substitution mechanisms of small molecule

model systems have been studied well, only a very little is known about the substitution

mechanisms that operate at the high polymer level. Therefore, it is assumed that the high

polymers also follow their small molecule precursors when it comes to substitution

mechanisms. With that assumption, the replacement of chlorine is believed to undergo

the substitution via SN2 reaction when the incoming nucleophile is an aryloxide or an

alkoxide. This is a bimolecular process in which the incoming nucleophile attacks the

phosphorus atom in the ring as the chlorine leaves as a chloride ion.41

P NCl

Cln

P NO R

O Rn

P NR

Rn

RONa

RM

RNH2 or (R2NH)P NNHR

NHRn

21

Scheme 1-8. Nucleophilic substitution (Nu- = -OR) via an SN2 mechanism42

These substitutions could proceed geminally—identical side groups on same

phosphorus—or non-geminally—on different phosphorus atoms. Non-geminal side

groups can be positioned cis or trans to each other.37 Whether or not a halogen

replacement follows a geminal or non-geminal route depends on many factors such as

steric bulk of the reagent, electron withdrawing or supplying character of the organic

group, solvent polarity and the type of halogen atom being replaced. The speed and

substitution pattern of the halogen replacement reactions depend on the different types of

substituents.42 The progress of these substitutions have been monitored by 31P NMR

spectroscopy, and the chemical shifts in phosphazenes have demonstrated acute

sensitivity to the types of side groups bound to the backbone phosphorus atoms.41

1.3.4. Bond Lengths and Bond Angles in Cyclo and Polyphosphazenes

Phosphorus-nitrogen bond lengths in cyclic and linear phosphazenes are in the

range of 1.47-1.62 Å and are shorter than the length of a single phosphorus-nitrogen

bond, which normally falls between 1.77-1.78 Å.49 This range of bond lengths can be

explained using the electronegativity of substituents on P. This suggests that

phosphazenes have some multiple bond character.50 As ring size increases, the bond

distance slightly decreases compared to cyclic trimer. In all cyclic phosphazenes, N-P-N

bond angles are found to be around 120 ° in order for a near-planar ring. In [PCl2N]n, N-

N NP

ClCl

NuN N

PClNu

N NPCl

ClNu -Cl

22

P-N angle is much lower than that of cyclophosphazenes.42 The P-N-P bonds are usually

larger than N-P-N angles. All the bond lengths and bond angles are summarized in Table

1-3.

Table 1-3. Bond lengths (Å) and bond angles (°) of [PCl2N]n and cyclophosphazenes.51

Skeletal flexibility is an inherent property of polyphosphazenes compared to other

organic polymers. This results because the substituents are arrayed in every other atom on

the backbone. Further, these substituents also orient in such a way as to move the

substituents as far apart as possible in a cis-trans planar conformation as shown in Figure

1-9.42,50

Figure 1-9. Cis-trans planar conformation of polyphosphazenes.42,50

1.3.4.1 Bonding in Cyclophosphazenes and Polyphosphazenes

In cyclic phosphazenes, phosphorus-nitrogen bond lengths are all equivalent and

are found to be smaller than the bond distances expected for single -P-N- bonds, which is

Phosphazenes P-N N-P-N P-N-PPDCP 1.44, 1.67 115 131(PCl2N)3 1.581 118.4 121.4(PCl2N)4 K form 1.57 121.2 131.3(PCl2N)4 T form 1.559 120.5 135.6(PCl2N)5 1.521 118.4 148.6

P N

P N

P N

P N

23

1.77 Å52 and higher than –P=N- double bonds.42 In cyclic trimeric phosphazenes,

phosphorus-nitrogen bond lengths range from 1.54 to 1.63 Å. Along with the bond length

studies and other experimental findings, it was suggested that the skeletal bonds in

phosphazenes are different from organic species, suggesting a unique type of bonding for

them.42 In each repeating –P-N- bond, both P and N have five valence electrons.

Phosphorus participates in four coordinate bondings whereas nitrogen engages only in

two. Figure 1-10 is a depiction of electron pairing in cyclotriphosphazene.42

Figure 1-10. Electron pairing in [PCl2N]3.42

According to Figure 1-10, the lone pairs on nitrogen are assumed to be located on

the plane of the ring in the sigma bond framework in an sp2 orbital.49 After assigning

electrons for sigma bonds, there are still six electrons from each atom to be accounted

for. The disposition of other six electrons, two per each repeat unit, has caused much

debate, and they have been the focus of bonding theories which is described below. Of

the different speculations, two theories can be considered more important in

understanding the bondings in cyclophosphazenes.42 One of the earliest theories was

based on dπ-pπ bonding model, in which the electron on nitrogen is placed in a 2pz orbital

whereas the electron on phosphorus is placed in a d orbital, 3dxz which overlaps with

nitrogen 2pz orbital. Craig and Paddock42,53 suggested an extended pi electron

delocalization within the pi-system. Because that explanation was not consistent with the

NP

NPN

P

24

experimental observations, Dewar proposed an “island” pi bonded model considering the

orbital symmetry, in which the electron delocalization is restricted to islands from one

phosphorus to the other. The d orbital symmetry leads to a node in the trimeric ring due

to an orbital mismatch at every phosphorus atom as shown in Figures 1-11.38,42,50

Orbital Mismatch

P1 N1 P2 N2 P3 N3 P1

Figure 1-11. Depiction of orbital mismatch in the dπ-pπ bonding structure of [PCl2N]3.42,54

The same theory applies to the linear polyphosphazenes. After assigning electrons

to the sigma bonds in polymer chain, four electrons per repeat unit are still unaccounted

for as depicted in Figure 1-12. Apart from the lone-pair of electrons on nitrogen atom, the

other electron on N is assigned to 2p-orbital whereas the one from P is accommodated in

a 3d-orbital. An out of plane dπ-pπ bond results from the spin-pairing of these two

electrons. Although this suggests an extended pi electron delocalization along the chain,

polyphosphazene backbone is found to be colorless and they are excellent insulators. This

is an indication of lack of extensive electron delocalization. But using the “island” dπ-pπ

bond as shown in Figure 1-13, those two properties of the backbone can be explained.50

There are exceptions to this bonding structure when polyphosphazenes are substituted

with groups containing chromophores or polymers with side groups with extensive π

conjugation.50

R

25

Figure 1-12. Electron pairing in [PCl2N]n.50

Islands of delocalization

Figure 1-13. Depiction of the dπ-pπ bonding in [PCl2N]n.50

This traditional interpretation on bonding in phosphazenes based on

delocalization that occurs via dπ-pπ overlapping was questioned in a review by Gilheany53

in 1994 as well as by Chaplin and co-workers,52 mainly due to the energy difference

between d orbitals on phosphorus and p orbitals on nitrogen. The d orbitals on

phosphorus are really high in energy compared to p orbitals on nitrogen and they interact

only in a very weak fashion. This was followed by ab initio calculations which say that

valence d orbitals play a little role in bonding of the main group elements.

The Zwitterionic description is another theory for both cyclo and

polyphosphazenes, and it was one of the earliest phosphazene models.50 The both

electrons on each repeat unit are accommodated in a p orbital on nitrogen due to its high

electronegativity, giving alternating positive and negative charges on the phosphorus and

nitrogen atoms, respectively. But in a review in 1972, Allcock proposes this suggested

N P N P N P N P

R

R

R

R

R

R R

R

26

zwitterion would be unstable. This theory of bonding explains the high flexibility of

phosphazene polymer backbone.49

In recent years, ionic bonding was explained along with the term known as

negative hyperconjugation, which is the best alternative to Dewar’s island model and the

best explanation of bonding in phosphazenes.50,52 According to that, phosphazenes have

strong ionic σ bonds and negative electron density (both in plane and out of plane lone

pair orbitals) on the nitrogen atoms. The negative electron density can back donate to

strongly polarized σ* orbitals of phosphorus and its substituents forming a π-type bond.

This has been supported by a variety of studies such as natural bond orbital (NBO) and

topological electron density analyses. From these studies, Chaplin and co-workers found

that ionic bonding was the dominant bonding feature whereas negative hyperconjugation

is necessary for a more complete description of bonding. This current theory, ionic

bonding/negative hyperconjugation, explains the flexibility of phosphazene backbone.

Further, it also explains the shortening of –P-N- bond with electronegative substituents

due to more efficient π-σ* overlap.50,52

Figure 1-14. Secondary ionic bonds of [PCl2N]3 (left) and [PCl2N]n (right).52

P

N P

Cl Cl

Cl

NP

Cl

N

nCl

Cl

N

PN

P

NP

ClCl

ClCl

Cl Cl

27

1.3.5 Applications of Polyphosphazenes

As discussed earlier, the ease of tailoring properties of polyphosphazenes via

macromolecular substitution has opened the door for a vast area of applications in recent

history.37,38 In addition to the properties arising from changing the side group structure,

different properties can also be generated by altering the polymer backbone’s

architecture. Once the living cationic condensation polymerization was explained, it has

been found that this route has allowed access not only to linear and block copolymers but

also to branched (star and dendritic) and comb structures. cyclolinear and cyclomatrix

polymers have also been produced recently.37

The structure of the polyphosphazene is related to the properties of the polymer.52

Polyphosphazenes have a wide spectrum of properties that range from elastomers through

films and coatings, fire retardants, and fibers to optical, electro-optical and biomedical

materials, solid battery electrolytes, fuel cell components, and a variety of different

membranes.38,50 Table 1-4 summarizes some of the applications of polyphosphazenes.

28

Table 1-4. Applications of Polyphosphazenes.38,50

1.4 Polyphosphazene based PEMs

Polyphosphazenes emerged as one of the promising materials for PEMs to be

used in both hydrogen/oxygen and in direct methanol fuel cells. This was due to the

inherent thermal and chemical stability of the backbone and the ease of tunability of

chemical as well as the physical properties of the polymer. The tunability of properties is

done by altering the array of side groups that can be incorporated into these polymers.55-58

They offer many advantages over classical perfluorinated polymers including Nafion®,

Aciplex®,

Properties/Applications CompoundsElastomers P[(OCH2C6H5)N]n

Fireproofing materials P[(OC6H4)(OC6H4C2H5)N]n

Passive membranes for gas and liquid separations P[(OCH2CF3)2N]n

Responsine membranes P[(OCH2CH2OCH2CH2OCH3)2N]n

Optical and photonic developments-High refractive index polymers P[(Br-C6H4-C6H4-OCH2CH2O)2N]n

-Nonlinear optical materials P[(NO2-C6H4CH=CHC6H4OCH2CH2O)2N]n

-Liquid crystalline polymers P[(OCH2C6H4-C6H4)2N]n

Solid conducting polymers-Lithium ion conductive polymers P[(OCH2CH2OCH2CH2OCH3)2N]n

in rechargeable Lithium batteries-Proton conducting polymers in fuel cell membranes P[(OC6H4CH3)(OC6H4SO2NHSO2CF3)2N]n

Fibers, films, and special surfaces-Waterproof fibers P[(OC6H5)2N]n

-Films as surface coatings P[(OCH2CF3)2N]n

-Adhesive surfaces P[(OCH2CF3)(OCH2(CF2)CF2H)N]n

Biomedical and biotechnologymaterials-Cardiovascular replacements, or as coatings for pacemakers or other implantable devices P[(OCH2CF3)(OCH2CF2)x-CF2H)N]n

-Local anesthetics P[(NHCH3)(NHC6H4C(O)O(CH2)2NEt2)N]n

29

Flemion ®, and Dow membranes as well as hydrocarbon based polymers, as discussed

earlier.12,56

The high thermo-oxidative stability of polymer backbone is a result of the highest

oxidation states of phosphorus and nitrogen.56 The stability against free radical cleavage

results from the polar nature of the bonding along the backbone. And the skeletal

flexibility of the backbone, which is in turn an important property to be used as a PEM to

facilitate a high proton conductivity, results from the absence of long-range conjugation

and the low barrier to skeletal free rotation about each phosphorus-nitrogen bond.42,50,56

The flexibility of these polymers is often defined in terms of the glass-transition

temperature, Tg. Below Tg, polymer is a glass and the backbone bonds do not have

sufficient thermal energy to undergo significant torsional motions. Above Tg, polymer

becomes an elastomer by allowing those torsional motions. Therefore, polymers with low

Tg allow more flexibility compared to polymers with high Tg. The magnitude of skeletal

flexibility is controlled by the type of incoming substituent. Consequently, polymers with

desired properties can be prepared by choosing the appropriate side groups.38,59 [PCl2N]n

has a Tg value of -66 °C that indicates the inherent flexibility of the backbone.38,42,60

Furthermore, these have been found to be resistant to radiological degradation because of

the lack of delocalized bonding.58,61-64

Poly(organo)phosphazenes suitable for PEMs were synthesized from [PCl2N]n.

However, they constitute a challenging design problem in that they should be stable to

aggressive oxidative and hydrolytic conditions at the operating temperature.55 Moreover,

they cannot be used directly as PEMs because they are not inherently conducting

polymers, and therefore, need to be doped with acids or modified to incorporate acid

30

functionalities.9,56 The acid functionalities must provide enough sites for high proton

conduction but not too high to generate excessive swelling in hot water or aqueous

methanol in the case of DMFCs.55 Therefore, the selection of side groups should be done

in such a way that it would achieve a balance between high conductivity and good

physical properties as well as allowing the polymer to be cross-linked in order to

overcome the deficiencies.56 The preferred polymers for this task are

poly(aryloxy)phosphazenes because they are some of the more thermally and chemically

stable polyphosphazenes that have been synthesized to date, and the ease of introducing

acid functionalities which act as proton transfer sites and the presence of alkyl groups that

provide sites for free radical cross-linking.55,56,58

1.4.1 Acid Functionalized Polyphosphazenes

There are three different types of acid functionalized polyphosphazenes reported

in the literature. They include sulfonic acid, phosphonic acid, and sulfonimide

functionalized polyphosphazenes.55,56

1.4.1.1. Sulfonic Acid Functionalized Polyphosphazenes

A. Sulfonated Polyphosphazenes

Sulfonation of poly(aryloxy)phosphazenes and poly(arylamino)phosphazenes

have been studied intensively in this regard. First, the sulfonated polyphosphazenes were

synthesized via post substitution, in which the desired poly(organophosphazene) is

synthesized and then sulfonation was carried out. Although the sulfonation was initially

developed by Montoneri, Gleria and co-workers in 198965,66 with the use of sulfur

trioxide with poly(aryloxy)phosphazenes and via sulfuric acid (either concentrated or

31

fuming) by Allcock and Fitzpatrick in 199167 with both poly(aryloxy)phosphazenes and

poly(arylamino)phosphazenes, none of those polymers were examined as possible

membrane materials.56-58

As an initial step towards PEMS to be used in fuel cells, Pintauro and co-workers

carried out sulfonation studies of variety of poly(aryloxyphosphazenes). 56,57,68,69 They

reported the synthesis of four different types of poly(aryloxyphosphazenes), compounds

I-1 to I-4 respectively shown in Figure 1-15, and sulfonated them to be used as potential

candidates for PEMs. Of the three possible synthetic routes towards water insoluble

sulfonated polyphosphazene membranes, sulfonation was carried out by the third route in

which an appropriate balance was obtained between the polymer’s

hydrophilicity/hydrophobicity and the crystallinity of the polymer. Thereby polymers

were sulfonated to such an extent that they swell and do not dissolve in aqueous media.57

I-1 I-2 I-3 I-4

Figure 1-15. Structures of poly(aryloxyphosphazenes). poly[(3- methylphenoxy) phenoxy)phosphazene, I-1: poly[(4-methylphenoxy)(phenoxy)phosphazene, I-2: poly[(3-ethylphenoxy)(phenoxy)phosphazene, I-3: poly[(4-ethylphenoxy)(phenoxy)phosphazene,I-4.57

P NO

On

CH3

P NO

On

CH3

P NO

On

C2H5

P NO

On

C2H5

32

The sulfonation was carried out according to the procedure reported by Montoneri

and co-workers.65,66 In that, the base polymer was first sulfonated with SO3 in

dichloroethane (DCE) and cast into membranes from N,N-dimethylacetamide (DMAc) or

1-methyl-2-pyrrolidone (NMP) at 80 °C. The resulting membranes were found to have a

thickness of approximately 200 µm. Using ion-exchange capacity (IEC),

methylphenoxyphosphazenes (compounds I-1 and I-2) were found to be resistant to

degradation, and the sulfonation degree was easily controlled in contrast to the two

ethylphenoxy polymers(compounds I-3 and I-4). They underwent a severe degradation

during sulfonation and were unusable as membranes.57

The results of sulfonation was in agreement with the work by Montoneri and co-

workers.65,66 They found that the phosphazene polymer backbone nitrogen atoms are

attacked first by SO3 during the sulfonation. Ring sulfonation happens after a certain

level of backbone complexation has been attained.

Scheme 1-9. The reaction scheme for polyphosphazene sulfonation with SO357

Of all four different poly(aryloxyphosphazenes), compound I-1 was found to be

the best starting material in terms of easiness of controlling the extent of sulfonation and

the magnitude of the ion-exchange capacity for a water insoluble polymer. Further,

P NO

On

R

+ 3 SO3 P NO

On

RHO3S

HO3S

SO3

33

sulfonated poly[(methylphenoxy)(phenoxy)phosphazenes]—sulfonated compounds I-1

and I-2—exhibited good mechanical and chemical properties. Table 1-5 compares

several properties of those polymers to three of the commercially available cation-ex

change membranes.

a (mwet – mdry) / mdry b measured in 0.5 M NaCl at 24 °C; area resistance = specific resistivity × membrane thickness. Table 1-5. Comparison of properties of sulfonated I-1, I-2 and commercial cation-exchange membranes.57

Pintauro and co-workers extended their studies on poly(aryloxyphosphazenes) to

be used as PEMs.58,68,69 In addition to sulfonation with SO3 in DCE at 0 °C, they cross-

linked the polymers by adding benzophenone photoinitiator to the casting solution. The

solution was cast on a surface, the solvent evaporated and the resulting films were

exposed to UV light.65 Poly[bis(3-methylphenoxy)phosphazene], compound I-5, shown

in Figure 1-16 was sulfonated and used in this regard, and it was also found to have a

better IEC compared to Nafion 117, 1.4 mmol/g. Cross-linking was done in order to

improve its performance, and it provided a means of independently controlling the ion-

exchange capacity of the membranes and the degree of polymer swelling by water.55,69

Ion-exchange membrane Type IEC Thickness Gel watera Area resistanceb

(mmol g-1) (mm) (%) (ohm cm2)Nafion (Du pont) Perflourinated sulfonic acid 0.9 0.2 16 1.5K101 (Asahi Chemical) Sulfonated styrene/ DVB 1.4 0.24 24 2.1R-5010-L (Pall RAI) Sulfonated LDPE 1.5 0.24 40 2-4I-1 Sulfonated polyphosphazene 1.5 0.2 58 1.6I-2 Sulfonated polyphosphazene 0.8 0.2 28 7.5

34

Such a high IEC value was obtained upon sulfonation without any noticeable

degradation.

Figure 1-16. Poly[bis(3-methylphenoxy)phosphazene (compound I-5).68

Several findings including high protonic conductivity (ranging from 4.0 × 10-2 S

cm-1 to 25 °C and 8.2 × 10-2 S cm-1 at 65 °C) combined with a low methanol diffusion

coefficient (8.5 × 10-8 cm2 s-1 at 45 °C) and a low water diffusion coefficient (between

6.7 × 10-8 cm2 s-1 at 25 °C and 1.2 × 10-7 cm2 s-1 at 65 °C) indicated that these cross-

linked membranes were a good candidate for possible use in PEMs in either H2/O2 fuel

cells or DMFCs. The mechanical stability of both uncross-linked and cross-linked was

performed with thermomechanical analysis, and the results showed that uncross-linked

polymers softened and deformed at 76 °C, but cross-linked polymers were stable up to

173 °C.58,68, 69

B. Blends of Sulfonated Polyphosphazenes

Pintauro and co-workers also focused their work on polymer blends of sulfonated

polyphosphazenes (henceforth denoted as SPOP) about a decade ago, targeting DMFCs

in order to improve their properties. Blending of polyphosphazene with another polymer

not only increases mechanical properties of the blended membrane, but also results in

P NO

On

CH3

CH3

35

lower methanol crossover. This occurs mainly due to two reasons; firstly, the other

polymer can restrict the SPOP swelling, making them virtually impermeable to water and

methanol, and secondly, thermoplastic properties of the other polymers will make hot

pressing electrodes easier during MEA fabrication.

a. Polyphosphazene/Poly(vinylidene fluoride) (PVDF) Blends

The previous studies on cross-linked sulfonated compound I-5 (denoted as SPOP)

found that they exhibited better properties to be a PEM in terms of proton conductivity

and methanol diffusion. Consequently, the first study involved blending this SPOP with

Kynar 761 poly(vinylidene fluoride) and Kynar FLEXTM (a copolymer of vinylidene

floride and hexafluoropropylene) separately. The membranes were prepared by mixing

SPOP with Kynar 761 or Kynar FLEX in DMAc solvent, and then the solution was cast

into membranes with a dry thickness of approximately 100 µm. Some of these

membranes were cross-linked by electron beam radiation. The non-cross-linked

SPOP/Kynar 761 flims exhibited water swelling in the range of 12-25%, which increased

with SPOP content when the percentage of Kynar was varied between 50% and 80%

while maintaining a constant IEC of 1.8 mmol/g of SPOP in the blend. The proton

conductivity followed the same trend (0.004 S cm-1 at 50% and 0.015 S cm-1 at 80% of

SPOP), and the methanol diffusivity was very small for all the blended membranes (<4.0

× 10-8 cm2/s).70-72 The proton conductivity for blended 75% SPOP/25% FLEX (IEC of

1.2 mmol/g) and cross-linked membrane is illustrated in Table 1-6.

36

Table 1-6. Proton conductivity of 75% SPOP/25% FLEX blended membrane in water.72

b. Polyphosphazene/Polyacrylonitrile (PAN) Blends

The same SPOP (sulfonated I-5) was later blended with polyacrylonitrile and

cross-linked by UV radiation in the presence of benzophenone as a photo initiator and

solution cast on a polypropylene surface. Once they were blended, it was found that the

mechanical properties of the films improved, the MEA fabrication became less difficult

due to the presence of PAN, and they exhibited low methanol crossover. The MEAs were

then evaluated in a DMFC at 60 °C with a 1.0 M aqueous methanol feed. Table 1-7

outlines several properties of these membranes as well as their comparison to Nafion 117.

In contrast to Nafion 117, all the SPOP/PAN films were thinner with a lower proton

conductivity, greater water swelling, and a lower methanol crossover.73

Temperature (°C) Conductivity (S cm-1)25 0.01440 0.01850 0.02270 0.027

37

Table 1-7. Comparison of properties of blended and cross-linked SPOP/PAN membranes for DMFCs.73 The DMFC current density/voltage curves for MEAs containing single

membranes are shown in Figure 1-17 (left). They were found to work well with a power

output nearly the same as that with Nafion 117 for current densities < 0.15 A/cm2, but

methanol crossover flux was three times lower than that of Nafion. Because SPOP/PAN

had lower proton conductivity, the electrochemical performance of single membrane

MEAs was poor although methanol crossover was very low. Due to the poor performance

of single membrane MEAs, multilayered MEAs were prepared. A two-layer (high IEC

SPOP/PAN MEA) and a three-layer (low IEC SPOP/PAN inner membrane) were used in

this regard, and their performance was compared to Nafion 117 in MEA. This is shown in

the Figure 1-17 (right). Of these two, the latter had methanol crossover about ten times

lower than that of Nafion 117 with a reasonably good current-density behavior.73

Membrane Composition Wet thickness (µm) IEC (mmol/g) Swelling water Proton Conductivity methanol crossover(g/g × 100)% (S cm-1) (10-6 mol/cm2-min)

55% 2.1 IEC SPOP 148 1.15 60 0.05 3.340% PAN5% benzophenone52% 2.1 IEC SPOP 137 1.1 50 0.04 2.143% PAN5% benzophenone48% 2.1 IEC SPOP 151 1 45 0.025 1.447% PAN5% benzophenone45% 2.1 IEC SPOP 158 0.95 37 0.008 0.7550% PAN5% benzophenoneNafion 117 220 0.909 35 0.06 9

Fan(r

c.

ph

p

ca

op

F

igure 1-17. Mnd methanolright). Repro

. Polyphosp

PEMs

hosphazene]

olybenzimid

Figure

Here P

ast membran

perating at 6

igure 1-19 (

Methanol ful fuel cell peoduced by pe

phazene/Poly

s were also p

]- compound

dazole (PBI)

e 1-18. Poly[

PBI was use

nes having th

60 °C with a

left) is a rep

uel cell perfoerformance wermission of

ybenzimidaz

prepared usin

d I-6, (this w

.74 The struc

bis(phenoxy

ed as a cross-

hickness ran

1.0 M aque

resentation o

38

ormance for bwith the two-f The Electro

ole (PBI) Bl

ng sulfonate

will also be d

cture of comp

y)phosphaze

-linking com

nging from 8

ous methano

of the curren

P NO

O n

blended SPO-layer and thochemical So

lends

d poly[bis(p

denoted as SP

pound I-6 is

ene (compou

mponent for t

2 –120 µm w

ol feed solut

nt-voltage cu

OP/PAN memhree-layer SPociety. 73

phenoxy)

POP) blende

shown in Fi

und I-6).74

the polyphos

were tested i

tion and amb

urves for fou

mbranes ( lePOP/PAN M

ed with

igure 1-18.

sphazene. Th

in a DMFC

bient pressur

ur different

eft) MEAs

he

re air.

S

D

es

2

w

in

FatmE d

su

p

C

p

an

POP-PBI bl

DMFC perfor

ssentially ide

.5 times low

was measured

n Figure 1-19

igure 1-19. Dttachment (le

membranes wElectrochemi

. Polyphosp

Burjan

ulfonated co

artially sulfo

CVEEP, hexa

lates. Two d

nd M2. Both

ended memb

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entical to tha

wer than that

d as 89 Mw

9 (right).

DMFC perfoeft) and pow

with direct elical Society.7

phazene/Hex

nadze and co

ompound I-6

onated with

a(vinyloxyet

different mem

h of them exh

branes along

h the 1.2 mm

at with Nafio

of Nafion 1

/cm2 compar

ormance of bwer density dlectrode attac74

a(vinyloxye

o-workers70 p

6, with an int

SO3 in DCE

thoxyethoxy

mbranes diff

hibited good

39

g with the ref

mol/g IEC SP

on 117. But

17.74 The ma

red to 96 of

blended SPOdependence ochment. Rep

thoxyethoxy

prepared PE

terpenetratin

E solution, an

y)cyclotripho

fering in CV

d mechanica

ference plot

POP membra

the methano

aximum pow

Nafion 117.

OP-PBI memon current deproduced by

y)cyclotripho

EMs using th

ng hydrophili

nd then the b

osphazene a

VEEP concen

al and therma

of Nafion 1

ane with 3 w

ol crossover

wer density o

. Those valu

mbranes withensity for SPpermission

osphazene (C

he SPOP men

ic network. T

blends were p

and cast onto

ntration are s

al stabilities,

17 based M

wt% PBI was

was found t

of the same b

ues are report

h direct electPOP-PBI of The

CVEEP) Ble

ntioned abov

The polyme

prepared wit

o polypropyl

specified as M

, and their IE

EA.

s

to be

blend

ted

trode

ends

ve,

r was

th

ene

M1

ECs

w

ra

to

(l

h

in

(r

Mcop

1

by

su

ad

in

gr

were 1.62 for

anged from 1

o M1 over th

left). The con

ave already

n section 1.4

right).

FigureM1 and M2 aonducting poermission of

.4.1.2. Phosp

The st

y Allcock an

ulfonic acid,

dditional adv

nitial phosph

roups into p

r M1 and 1.7

150-200 µm

he entire rang

nductivity o

been discuss

4.1.2, and it r

e 1-20. Comat high and loolymer matef Elsevier.70

phonic Acid

tudies on ph

nd co-worke

, due to its lo

vantage is th

honation reac

olyphosphaz

79 mmol/g fo

m. Membrane

ge of temper

f M2 was al

sed) and also

reported the

mparison of thow water parerials in a wa

d Functionali

hosphonic ac

ers. Although

ower hydrop

hat, phospho

ctions were c

zenes throug

40

or M2 respec

e M2 showed

ratures and p

so compared

o to phospho

lowest cond

he temperaturtial pressurater swollen

ized Polypho

id functiona

h phosphonic

philicity, wat

nation was e

carried out b

gh a phospho

ctively. The

d a much bet

partial pressu

d to other su

onated system

ductivity. It i

ure dependenres (left) and

state at 25 °

osphazenes

alized polyph

c acid is a w

ter uptake w

easy compar

by introducin

orus-oxygen

thickness of

tter conducti

ures as show

ulfonated sys

ms which w

is shown in F

nt conductivd conductivit°C (right). R

hosphazenes

weak acid com

was expected

red to sulfon

ng the phosp

-carbon link

f the membr

ivity compar

wn in Figure

stems (which

will be discus

Figure 1-20

vities for samties of variou

Reproduced b

s were carrie

mpared to

to be less. A

nation.56 The

phate penden

kage. But tho

ranes

red

1-20

h

ssed

mples us by the

ed out

An

nt

ose

41

polymers were susceptible to hydrolysis and thermal cleavage, limiting their suitability as

PEM in fuel cells. Consequently, instead of this phosphorylation, the focus of the studies

was directed towards incorporating pendent phosphate groups into aryloxyphosphazenes

through phosphorus-carbon linkages (phosphonate linkages). This approach increased the

thermal and chemical stability of the polymers.75

Initially two different approaches were carried out incorporating dialkyl

phosphonate units into the side groups of poly(aryloxy)phosphazenes. In the first

approach, bromomethylene-phenoxy polyphosphazenes were treated with a sodium

dialkyl phosphite as shown in Scheme 1-10. This route proceeded with 100 %

conversion. In the second approach (Scheme 1-11), polyphosphazenes bearing

bromophenoxy side groups were treated with n-butyllithium, resulting the corresponding

lithiophenoxy derivative. Addition of diphenyl chlorophosphate followed by basic

hydrolysis and acidification with hydrochloric acid yielded the desired product in 80-85

% conversion.76 This is the approach which was utilized in synthesizing phosphonic acid

functionalized poly(aryloxy)phosphazenes as PEM candidates over the first method due

to the required bromination and purification of poly[bis(4-methylphenoxy)phosphazene]

before phosphonation in prior method.

42

Scheme 1-10. Phosphonation of poly(aryloxy)phosphazenes bearing bromomethylene-phenoxy side groups76

The polymers of interest were polyphosphazenes co-substituted with either 4-

methylphenoxy or 3-methylphenoxy derivatives (I-7 and I-8 respectively) as shown in

Figure 1-21, and the synthesis of those polymers are illustrated in Scheme 1-11. Four

different polymers were synthesized by varying the molar ratio of x and y.

1-7 I-8

Figure 1-21. Phosphonic acid functionalized poly(aryloxy)phosphazenes (compounds I-7 and I-8).77,78

P NO

OP NO

O

CH3

CH3

CH2Br

CH3

1.6 0.4

P NO

OP NO

O

CH3

CH3

CH2P(OCH3)2

CH3

1.6 0.4

O

P(O)(OMe)2Na

THF, 25 °C

P NO

OP NO

O

P(OPh)(OH)

P NO

O

HO

x 0.5y 0.5y

CH3 CH3 CH3

CH3

P NO

OP NO

O

CH3

CH3

P(OPh)(OH)

CH3

P NO

O

H

CH3

O

x 0.5y 0.5y

43

I-7 and I-8 Scheme 1-11. Phosphonation of poly(aryloxy)phosphazenes via lithiophenoxy side groups. I-8* is analogous to polymer I-7b, however the methyl groups are in the 3-position rather than the 4-position77,78

Once they were synthesized and phosphonated, their membranes were obtained

by casting from 5-6% solutions (w/v) of N,N-dimethylformamide (DMF) onto a

poly(propylene) plate and by drying in a vacuum oven at room temperature for 24 h

followed by drying at ~45 °C for 48 h. The cross-linking was done by 60Co γ- radiation.

Experimental IEC values of these membranes ranged from 1.17-1.43 meg. g-1, and

P NO

OP NO

O

CH3

CH3

Br

CH3

x y THF, - 75 °C

1). t-BuLi

2). P(O)(OPh)2ClP NO

OP NO

O

CH3

CH3

P(OPh)2

CH3

P NO

O

H

CH3

O

x 0.5y 0.5y

P NO

OP NO

O

CH3

CH3

P(OPh)(OH)

CH3

P NO

O

H

CH3

O

x 0.5y 0.5y

THF1). 1.0 M NaOH

2). 0.1 M HCl

x yI-7a 1.26 0.74I-7b 1 1I-7c 0.8 1.2I-8* 1 1

44

equilibrium water swelling ranged from 19 to 32 wt%. Protonic conductivities of fully

hydrated membranes at room temperature were in the range of 3.8 × 10-2 to 5.4 × 10-2 S

cm-1. These were roughly half of those obtained for Nafion 117. Methanol crossover

studies were also carried out for compound I-8 derivative. At 80 °C and 2.8 bar with a 3

M aqueous methanol fuel feed, the polymer had roughly 12 times lower methanol

crossover than Nafion (0.27 × 10-6 mol min-1 for the phosphonated polyphosphazene

versus 3.39 ×10-6 mol min-1 for Nafion 117) and 6 times lower than for a cross-linked

sulfonated polyphosphazene membrane (1.58 × 10-6 mol cm-2 min-1), proving its

excellent candidacy to be used as PEMS on DMFCs and in H2/O2 fuel cells.77

At the same time, a few studies were carried out to compare methanol diffusion of

Nafion 117 with the newly found sulfonated and phosphanated polyphosphazenes.

Fedkin and co-workers79 showed those two types of phosphonated species had the values

of methanol diffusion about 40 times lower than for Nafion 117 and about 10-20 times

lower than for the sulfonated membranes with 50% (v/v) aqueous methanol. Therefore,

these membranes further proved their applicability in DMFCs as an alternative to Nafion

117.

Up to now, for ambient temperature DMFCs, phosphonated polyphosphazenes

outperformed Nafion due to low methanol crossover, low water swelling ratios, and good

mechanical properties along with the comparable proton conductivity to that of Nafion.

But in order to overcome the low performance of ambient temperature operating DMFCs,

it was necessary to increase the function of PEMs at elevated temperatures for a high

efficiency of DMFCs. Consequently, Zhou and co-workers extended their work on those

45

sulfonated and phosphonated poly[(aryloxy)phosphazenes] at elevated temperatures up to

120 °C to investigate their conductivity and methanol permeability.80

The membranes of Nafion117, sulfonated poly[(aryloxy)phosphazenes] and

phosphonated poly[(aryloxy)phosphazenes] were each cross-linked with 60Co γ-radiation

using the dosing levels specified in Table 1-8. The measured average conductivity of the

membranes at different temperatures are summarized in Table 1-9 and plotted in Figure

1-22. Although the conductivity increased with the increase in temperature, they still

remained lower than Nafion 117.79

Table 1-8. Membrane properties of selected polymers.80

Table 1-9. Proton conductivity of Nafion 117, sulfonated polyphosphazene, phosphonated polyphosphazene at different temperatures.80

Polymer Membrane Crosslinking (Mrad) IEC (meq g-1) Swelling (%) Conductivity (S cm-1)Nafion 117 N/A 0.91 30 0.07Sulfonated polyphosphazene 20 1.07 38 0.035Phosphonated polyphosphazene 40 1.35 14 0.025

Average Conductivity (S cm-1)Average Nafion 117 Sulfonated PhosphonatedTemperature (°C) polyphosphazene polyphosphazene

20 0.0352 0.055621 0.072240 0.138 0.081 0.06860 0.19 0.111 0.10280 0.305 0.128 0.131

100 0.344 0.172 0.161110 0.252 0.124120 0.204125 0.416

FanR

m

ex

ca

D

1

co

p

igure 1-22. Rnd the select

Reproduced b

At ele

methanol cro

xhibited a va

andidacy no

DMFCs over

0.

The se

ompared to N

olyphosphaz

T/ °C

2580

120

Regression ctivity of protby the permi

evated tempe

ssover value

alue about n

t only in low

Nafion. The

Table

electivity of

Nafion 117.

zene is super

MeONafion 117

7.924.2510.5

curves of conton conductiission of The

eratures, alth

es close to N

ine times low

w temperatur

e average va

1-10. Metha

f proton cond

As shown in

rior to Nafio

OH Diffusion 7 Sulfonate

46

nductivity vive membrane Elsevier.80

hough sulfon

Nafion 117, p

wer than tha

re DMFCs b

alues of meth

anol permea

ducting mem

n Figure 1-2

on 117 at tem

(× 10-6 cm2

ed polyphosph1.481.419.4

s. T-1 and acnes as a func

nated polyph

phosphonated

at of Nafion,

but also in hi

hanol crosso

ability tests.8

mbranes was

22 (right), the

mperatures b

s-1)hazene Phos

ctivation enection of temp

hosphazenes

d polyphosp

indicating th

gh temperatu

ver are illust

0

also calcula

e sulfonated

elow 85 °C

sphonated po2.72.08.5

ergies (left) perature (rig

exhibited

phazenes

heir potentia

ure perform

trated in Tab

ated and

d

whereas

olyphosphazen770859

ght).

al

ing

ble 1-

ne

47

phosphonated polyphosphazene is superior to Nafion 117 over a wide temperature range

from 22 to 125 °C.80

1.4.1.3. Sulfonimide Functionalized Polyphosphazenes

As an alternative to previously reported polyphosphazenes functionalized with

sulfonic and phosphonic acids, sulfonimide containing polymers were also synthesized

by Allcock and co-workers because they could bring high acidity to PEMs.57,81 The

compound which was studied intensively for PEMs was co-substituted with sulfonimide

and 4-methylphenoxy side groups (compound I-9, Scheme 1-13)

Scheme 1-12. Synthesis of aryl sulfonimide side group71

NaO SO

O

NaN S

O

OCF3

H3CO SO

O

NaN S

O

OCF3

H3CO SO

OCl

H3CO SO

ON S

O

OCF3

H:E

t 3N

CF3SO2NH2, Et3N

Acetone, RT, 24 hrs

CH3ONa

CH3OH

CH3CH2SNa DMF, reflux3 hrs

48

The synthesis was achieved first by synthesizing the aryl sulfonimide side group as

shown in Scheme 1-12 and then by replacing chlorine in a 50 % 4-methylphenoxy chloro

polymer by that sodium sulfonimide followed by further addition of sodium 4-

methylphenoxide at 150 °C in a sealed pressure reactor.71 The synthesis of sulfonimide

functionalized polyphosphazene is outlined in Scheme 1-13.

I-9

Scheme 1-13. Synthesis of sulfonimide functionalized polyphosphazenes71

H3C ONa

P NCl

Cln

THF, RT, 1h

NaO SO

O

NaN S

O

OCF3

THF, Bu4NBr, Reflux,48 hrs

P N

O CH3 n

Cl

H3C ONa THF, sealed autoclave, 150 °C, 30 hrs

OP N

O SO

NaN S

O

OCF3

O CH3

P N

Cl

O CH30.34n 1.66n

OP N

O SO

NaN S

O

OCF3

O CH3

P N

O

O CH30.34n 1.66n

CH3

49

The membranes were cast from 1,4-dioxane, and then their proton conductivities,

water swelling and thermal properties were determined both before and after cross-

linking. The results obtained are given in Table 1-11. Compared to Nafion and other

perfluorinated sulfonic membranes, these acid functionalized phosphazenes also need to

be hydrated for proton conduction across the membrane. Sulfonimide functionalized

polyphosphazenes were found to have good proton conductivities and moderate water

swelling, depending on cross-linking density. But they still had lower proton

conductivities and higher water swelling compared to Nafion 117.71

Table 1-11. Membrane properties of sulfonimide functionalized polyphosphazenes compared to Nafion 117.71

Because blending of polyphosphazene increased the mechanical strength of the

polymer membranes in the previous studies, this phosphonated polymer was also blended

with poly(vinylidene fluoride) (PVDF) in a 75/25% w/w ratio and then fabricated into

membranes by solution casting from DMAc. This blend exhibited similar results to those

found for the pure sulfonimide membrane after a cross-linking dosage of 40 Mrad.

However, it had improved mechanical properties.71

Another recent study on these sulfonimide functionalized polyphosphazenes was

carried out by Zheng-Bo and co-workers.82 Based on their previous studies, it was found

that perfluoroalkylsulfonylimide group had higher acid strength than

Membrane Thickness (cm) IEC (mequiv/g) Water swelling Proton Conductivity Crosslinking(% H2O/dry wt) (S/cm) (Mrad)

Nafion 117 0.02 0.91 30 0.1 0Sulfonimide 0.013 0.99 119 0.049 0Sulfonimide 0.011 0.99 73 0.071 20Sulfonimide 0.009 0.99 42 0.058 40PVDF/ sulfonimide blend 0.015 41 0.06 0

50

trifluoromethylsulfonylimide group83 described in Scheme 1-12. Therefore, Zheng-Bo

and co-workers expanded their studies by incorporating this perfluoroalkylsulfonylimide

group into poly(diphenoxyphosphazene), PDPA as a pendent group.82 The synthetic

scheme is shown in Scheme 1-13. The application of this polymer as a PEM has not been

reported.

Scheme 1-14. Synthesis of perfluorobutylsulfonylimide functionalized polyphosphazenes82

Table 1-12 summarizes the electrochemical properties of all three acid

functionalized cross-linked pure polyphosphazene membranes compared to Nafion 117.

Sulfonated polyphosphazene exhibited the lowest proton conductivity whereas

sulfonimides maintained the highest conductivity. Although none of those three beat

P NO

OP NO

O

SO2Cl

SO2Cl

P NO

O

SO2Cl

0.57n 0.16n 0.27n

P NO

OP NO

O

SO2NHSO2C4F9

SO2NHSO2C4F9

P NO

O

SO2NHSO2C4F9

0.57n 0.16n 0.27n

P NO

O n

P NCl

Cln

ONaClSO2OH

SOCl2

1. C4F9SO2NH2

2. HCl

51

Nafion in terms of proton conductivity, they were all found to have a very low methanol

diffusion, suggesting their candidacy as PEMs in DMFCs in order to overcome the severe

problem related to Nafion 117.57

a 100% relative humidity, 25 °C. b 12 M MeOH, 80 °C, 2.8 bar. Table 1-12. Comparison of electrochemical properties of acid functionalized polyphosphazene with Nafion 117.56 1.4.2 Low-humidified or Novel Non-humidified PEMs based on Polyphosphazenes Because all the acid functionalized PEMs act under humidified conditions, they

all suffer from a common problem that when temperature increases, conductivity

gradually decreases. As a result, all the PEMs mentioned above operate at low

temperatures, < 100 °C.84 The development of solid proton conducting electrolytes which

are capable of exhibiting high proton conductivity at low medium temperatures (120- 160

°C) in the anhydrous state or low humidity environment emerged as an

alternative.84-86

A. Polyphosphazene-Phosphoric Acid (PA) Composites as PEMs

The choice of phosphoric acid as the protonating agent was because it shows

10-1 S cm-1 proton conductivity in a dry environment.86 Due to its structure, which

contains three protons with a different acidity per molecule, it can act both as a proton

Polymer IEC Crosslinking Conductivitya Water MeOH (mmol g-1) (Mrad) (× 10-2 S cm-1) Swelling (wt %) Diffusionb (× 10-6 cm2 s-1)

Nafion 117 0.91 - 10 30 6.22Sulfonated 1.07 20 1.1 38 1.02Phosphonated 1.35 20 4.4 13 0.77Sulfonimide 0.99 20 7.1 73 -

52

donor and as a proton acceptor, and can establish a long chain of intermolecular H-bonds

through which protons may transfer even in the absence of water. Instead of the vehicle

mechanism, the Grotthus mechanism appears to be operative in which protons hop from

one active site to another.17-19 Several polyphosphazenes doped with phosphoric acid

have therefore been investigated as possible proton conductors in dry or low humidity

conditions.86

Figure 1-23. Proton transfer via Grotthus mechanism.17-19

a. Poly(dipropyl)phosphazenes/Poly-paraphenylenesulfide Composite (PPS-PDPrP-PA)

Dotelli and co-workers started working with a series of

poly(dialkyl)phosphazenes as suitable candidates in this regard. Preliminary investigation

indicated poly(dipropyl)phosphazenes (denoted as PDPrP) shown in Figure 1-24 as the

most suitable poly(dialkyl)phosphazene to obtain solid polymer electrolytes. The

protonated species was prepared by dissolving PDPrP in 99% HCOOH at 0.5 g/mL

concentration and then adding 85% aqueous H3PO4 to the solution at 0.5-3 H3PO4/N

mole ratio. Although the protonated polymer, PDPrP.nH+, appeared to be a good

candidate, it could not be cast into films having high mechanical strength which would

tolerate fuel cell operating conditions.84 Therefore, a composite material was synthesized

with the use of PPS (poly-paraphenylenesulfide), Ryton® (Figure 1-24) and the

protonated composite exhibited better mechanical properties due to the presence of PPS

+ + +++ + +

53

and good proton conductivity due to PDPrP-PA. The electrical conductivities of PPS-

PDPrP.nH+ were measured in the range 29 - 79 °C and in 0 - 33 % relative humidity

range.84

Figure 1-24. Structures of poly(dipropyl)phosphazene (PDPrP) (left) and PPS (right).84

Table 1-13 summarizes the proton conductivity measurements. In all cases,

conductivity was found to increase with increasing temperature and relative humidity.

The highest conductivity for the composite was 1.37 × 10-3 S cm-1 at relatively low

temperature (52 °C) at relative humidity 33%. The conductivity values fall in the range

reported for sulfonic and phosphonic acid functionalized polyphosphazenes when

operated at similar reaction conditions. Under 0% relative humidity operating conditions,

the highest conductivity reported was in 10-4 S cm-1 at 69 °C. This is higher than the

conductivity values obtained for sulfonic polymers (10-6 - 10-5 S cm-1) at 100 °C proving

their suitability as PEMs.

Table 1-13. Conductivity of PDPrP.nH+ at 1H3PO4/N mole ratio in PPS net composite at variable temperature and relative humidity (RH, %).84

1st cycle (dry) 2nd cycle (dry) 3rd cycle (11% RH) 4t cycle (33% RH) 5th cycle up (dry) 5th cycle down (dry)T (K) σ (S cm-1) T (K) σ (S cm-1) T (K) σ (S cm-1) T (K) σ (S cm-1) T (K) σ (S cm-1) T (K) σ (S cm-1)303 1.44 × 10-7 313 1.98 × 10-6 304 7.46 × 10-7 300 1.80 × 10-5 302 8.67 × 10-7 334 3.59 × 10-5

307 2.36 × 10-7 318 3.72 × 10-6 308 1.39 × 10-6 309 7.42 × 10-5 304 1.25 × 10-6 325 1.26 × 10-5

314 4.24 × 10-7 322 6.46 × 10-6 311 2.57 × 10-6 317 3.01 × 10-4 309 2.22 × 10-6 317 3.91 × 10-6

323 1.34 × 10-6 325 1.13 × 10-5 313 4.70 × 10-6 325 1.37 × 10-3 314 4.31× 10-6 308 1.05 × 10-6

331 4.16 × 10-6 30 2.17 × 10-5 317 8.66 × 10-6 318 8.00× 10-6 301 2.36 × 10-7

341 1.44 × 10-5 334 4.44 × 10-5 323 1.56 × 10-5 322 1.40 × 10-5

337 7.88× 10-5 326 3.03 × 10-5 327 2.29 × 10-5

342 1.38 × 10-4 330 5.45 × 10-5 331 3.37 × 10-5

335 1.11 × 10-4 339 7.08 × 10-5

338 1.95 × 10-4 342 1.04 × 10-4

P NPr

Pr n

Sn

54

b. Poly(dipropyl)phosphazenes/sulfonated poly[(hydroxy)propyl, phenyl ether] Composite (SPHPE-PDPrP-PA)

In the next study, the composite polymer, SPHPE-PDPrP-PA, was made by

Dotelli and co-workers with the use of sulfonated poly[(hydroxy)propyl, phenyl ether]

(SPHPE, Figure 1-25) instead of PPS that was used in their previous study because

SPHPE had good mechanical strength and strong –SO3H proton donor groups.85 The two

polymers were synthesized separately and then fabricated into a composite membrane.

The protonation was carried out by soaking with 85% H3PO4 for 18 hours. Once

protonated, each polymer repeat unit contained 1 mol of phosphoric acid. Conductivity

data for both composites, SPHPE-PDPrP-PA and PPS-PDPrPHP are plotted together in

Figure 1-26. They were done at dry conditions and at 11% relative humidity. Although

both materials show the dependence of conductivity on temperature and relative

humidity, the prior was always more conductive than the latter mentioned above. The

highest conductivity measured was 7.10 × 10-3 S cm-1 in 0% relative humidity at 127 °C.

This value remains one of the highest conductivities reported in the literature.

Figure 1-25. Structure of SPHPE.85

CH3

CH3

O OOH

nSO3H

v

FP c.

el

su

th

Table 1-14.ariable temp

igure 1-26. LPS-PDPrP-P

. Poly(diethDPrP-PA)

In a re

lectrolyte of

ulfonated co

hermal stabil

S1T33333333

Conductivitperature.85

Log10 σ vs. 1PA dry ( ) an

yl, dipropyl)

ecent study b

f poly(diethy

opolyimide (S

lity and the s

SPHPE-PDPr11% RHT (K)318 (1)330 (1)338 (1)329 (2)319 (2)339 (4)328 (4)318 (4)

ty of SPHPE

1000/T of SPnd at 11% R

)phosphazen

by the same

yl, dipropyl)p

SPI) that wa

solubility req

rP-PA

σ (S cm4.79 × 17.39× 101.54× 101.28× 109.35 × 11.51 × 11.11 × 17.55 × 1

55

E-PDPrP-PA

PHPE-PDPrRH ( ). Repr

ne/Naphthale

research gro

phosphazene

as doped with

quirements.

Drym-1) T (K)

0-4 297 (0-4 308 (0-3 318 (0-3 329 (0-4 339 (0-3 358 (0-3 374 (0-4 378 (

400 (

A under dry c

rP-PA dry (roduced by th

enic sulfonat

oup, they ma

e (PDEt, DP

h PA.86 Both

The two cop

)(3) 2(3) 3(3) 4(3) 6(3)(3)(3)(3) 4(3)

conditions an

) and at 11%the permissio

ted Copolyim

ade a new co

rP) and the n

h of the copo

polymers, PD

σ (S cm-1)2.27 × 10-4

3.19 × 10-4

4.32 × 10-4

6.00 × 10-46.73 × 10-4

1.09 × 10-3

3.14 × 10-3

4.93 × 10-3

7.10 × 10-3

nd 11% RH

% RH ( ), anon of Elsevie

mide (SPI-P

omposite

naphthalenic

olymers fit th

DEt, DPrP a

at

nd of er.85

DEt,

c

he

and

56

SPI (shown in Figures 1-27 and 1-28, respectively) were synthesized separately and

fabricated into composite membrane with solid PA.

Figure 1-27. Poly(diethyl, dipropyl)phosphazene (PDEt, DPrP).86

Figure 1-28. Sulfonated polyimide (SPI).86

The films were cast by solution casting in DMSO. After the films were dried, two

transparent, homogeneous and non-crystalline free standing films with a thickness of

110-125 µm were obtained with SO3H/N/PA mole ratios of 0.24:1:1 and 0.61:1:1. The

composite films were stable in the low medium temperature range (<160 °C), which is

the desired temperature of operating fuel cells. The conductivity measurements were

performed in a dry environment and at 11% RH in the 30 -127 °C temperature range. The

results of the two SPI-PDEt,DPrP-PA and composites, which were reported earlier, are

summarized in Figure1-29 (PPS-PDPrP-PA and SPHPE-PDPrP-PA).

N N O

O

OO

O

N N

O

OO

O

HO3S

SO3H

2

12 . H2O

P NEt

Et 2.6

P NPr

Pr

57

Figure 1-29. Log10 σ vs. 1000/T for different N containing materials doped with PA at variable H3PO4/N mole ratio in dry conditions. Reproduced by the permission of Elsevier.86

Although, the rationalization of the observed order of conductivity was difficult, it

can be concluded that the complete protonation of the phosphazene sites and the higher

chemical homogeneity attained in the SPI-PDEt, DPrP-PA composite did not result in an

expected conductivity enhancement relative to the SPHPE-PDPrP-PA composite.86

B. Azole Substituted Polyphosphazenes as PEMs In a recent publication by Bozkurt and co-workers,87 they explain the novel non-

humidified proton exchange membranes based on azole substituents that operate at higher

temperatures in the anhydrous state. The desired polymers were synthesized according to

the Scheme 1-15 shown below. Poly(aryloxy)chlorophosphazene (PEMPC) was

synthesized starting with the [PCl2N]n from ring opening polymerization of [PCl2N]3. The

azoles, triazole (Tri) and aminotriazole (ATri) were each substituted separately to

PEMPC backbone, resulting in two novel polymers, TriP and ATriP, respectively.

Polymer samples were dissolved in methanol and doped with the strong acid,

58

trifluoromethane sulfonic acid (TA) by adding various molar ratios (0.5, 1, 2 and 3) with

respect to the azole unit. The resultant solution was cast on to PTFE plates and dried in

vacuum. The thermal stability of the pure polymers and TA doped materials were

determined by the TGA, and they were stable up to approximately 150 °C, indicating

their chemical stability to be used in PEMFCs. The flexible membranes obtained from

that were then sandwiched between Pt electrodes, and AC conductivity, σac (ω) was

measured using high resolution dielectric impedance spectroscopy at several

temperatures. The AC conductivity was found to increase as the temperature increased

gradually as shown in Figure 1-30.

Scheme 1-15. Synthesis pathway of TriP and ATriP starting from [PCl2N]3

87

NP

NPN

PClCl

Cl Cl

ClCl

P NCl

Cln

NaO CH3

P NO

Cl

CH3

nP NO

ON

n

CH3

NN

P NN

OP NO

NH

CH3

NHN

N

NN

H2N

CH3

x y

n

250 °C

THF, RT, 1h

TriP

ATriP

N

HN

N

Et3N, Reflux

Et3N, RefluxN

N

HN

NH2

PDCP PEMPC

Fte

T

v

te

Fvp

d

igure 1-30. Aemperatures

The DC cond

s. log F by li

emperature.

igure 1-31. Various TA coermission of

From

opant conce

AC conducti(right). Rep

ductivities of

inear fitting o

The DC con

Variation of oncentrationf The Royal

TriP isother

ntration incr

ivity vs. freqroduced by p

f those polym

of the data, a

nductivity iso

f the proton cns as a functiSociety of C

rms, it was fo

reases only u

59

quency of Trpermission o

mers were al

and they dem

otherms are

conductivityion of reciprChemistry.87

found that the

until a certain

riP1TA (leftof The Roya

lso derived f

monstrated a

shown below

y of the TriP rocal temper

e proton con

n threshold r

) and ATriPal Society of

from the plat

a strong depe

w in Figure

(left) and Aature. Repro

nductivity in

ratio, and af

2TA at sevef Chemistry.8

teaus of log

endence on

1-31.

ATri (right) woduced by

ncreases as th

fter that, with

eral 87

σac

with

he

h the

60

presence of excess acid, it starts to decrease the conductivity. The maximum proton

conductivities obtained for anhydrous TriP2TA and ATriP2TA as 3 × 10-3 S cm-1 at 50

°C and 0.0412 S cm-1 at 130 °C, respectively. The major discovery is that considering all

the conditions—stable film forming and considerable high proton conductivity—

ATri0.5TA forms the optimum composition for use in PEMFCs. The proton conductance

occurrd as a result of the transport of protons among the protogenic solvents via the

Grotthuss mechanism. The acidic protons transfer along the unprotonated and protonated

triazoles in the polymer. Therefore, it is necessary to have free immobilized nitrogen sites

in the polymer. The conductivity of TriP and ATriP systems results from proton hopping

not only from one N-H site to a free nitrogen but also from one N-H site to sulfate ions.87

1.5 Conclusion

As evident from the discussion in Chapter I, the fuel cell technology depends

mainly on Nafion®, which is one of the perfluorinated proton exchange membranes.

However, it suffers from a few major drawbacks due to its dependence on humidity for

proton conduction, and therefore, complexities arise with water management.

Consequently, to address these drawbacks as well as for the advancement of fuel cell

technology, the research was steered towards alternative PEMs. Polyphosphazenes

emerged as one of the most promising candidate in this respect due to the inherent

properties that this inorganic polymer possesses.

The main focus of this section is on the progress of proton exchange membranes

based on polyphosphazenes that have been synthesized so far. Initially,

polyphosphazenes were functionalized using different acids giving rise to sulfonic acid,

61

phosphonic acid and sulfonimide functionalized polyphosphazenes. In many cases,

though they were better in terms of methanol crossover, but fell behind in terms of proton

conductivity compared to Nafion®. All of these membranes also depended on humidity.

With the advancement of fuel cell technology, the need for medium-temperature

operating membranes took place, and researchers were interested in synthesizing

polymers which can operate at medium temperature (120 – 160 °C) with low humidity.

One of the best examples for this type of polymers are poly(alkyl)phosphazene

composites doped with phosphoric acid.

A relatively new area is the search for anhydrous proton conducting polymers

which operate at higher temperatures, and only a handful of researchers have been

actively engaged in it. The nitrogen-containing heterocycles substituted to

polyphosphazenes were used as possible proton conducting polymers in this regard due to

the known high conductivity of some of azoles in the anhydrous state. The recent study

on triazole and aminotriazole co-substituted polyphosphazene doped with triflic acid have

shown a higher conductivity at high temperature (130 °C) in anhydrous state along with

their chemical stability for applications in PEMFCs. Therefore, PEMs based on nitrogen-

containing heterocycles substituted to polyphosphazene seem to be one of the most

promising candidates in current fuel cell research compared to many other alternatives.

62

CHAPTER II

SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF

HEXACYCLOTRIPHOSPHAZENES AS MODEL COMPOUNDS TO

POLY(ORGANOPHOSPHAZENES)

2.1 Introduction

Although cyclic phosphazene synthesis goes back to the 19th century,88 it was not

until 1950s that researchers started studying these small molecules more intensively. Out

of the different types of small molecules available, cyclic trimers, have been studied in

greater detail due to their ease of synthesis and the availability of starting materials in

large quantities. Most cyclophosphazenes are crystalline solids and can be studied by

single X-ray diffraction. Therefore, these model compounds can be used as synthetic,

mechanistic, or structural substitutes for phosphazene high polymers due to the simplicity

of synthesis, purification, and characterization.38

There have been hundreds of different reactions aimed at the preparation of cyclic

phosphazene trimers alone, and most of those reactions can be used as model compound

studies for the high polymers.38 In all of these cyclic phosphazenes, these derivatives are

prepared mainly through nucleophilic substitution of chlorine atoms with substituent

groups such as alkoxy, aryloxy, amino, alkyl, aryl, inorganic or organometallic units and

by secondary or tertiary chemical reactions on organic or inorganic side groups already

63

present on the cyclic phosphazene.38 Over the years, there has been a great interest in

improving synthetic procedures towards cyclophosphazenes to obtain high yields in

shorter time. The results depend on the type of the substituent, the solvent, type of base,

reaction temperature and other factors.

The alkoxy and aryloxy substitutions have been studied in great detail among all

the possible substitutions. One of the best known cycloalkoxyphosphazenes is where

substituent is -OCH2CF3.89 The rate of aryloxy substitutions was found to be slower than

that of the alkoxy substitutions due to the steric bulk of aryloxides. Different types of

aryloxyphosphazenes have already been synthesized where they have the common

formula [PN(-OC6H4R)2]3 in which R = H,90,91 2- or 4-Me,90 2- or 4-Et,92 t-Bu,90 OMe,90

4-OPh,92 4-CPh3,92,93 4-COOR,90 4-F,90 4-Br,91 4-CN,91 4-NO2.

90,91 Many of these

compounds are found to be models for the respective high polymers. Overall, one of the

best methods to understand the behavior of high polymers are the studies on these

aryloxides with model systems, which also helps the development of reaction conditions

to be employed at macromolecular syntheses.38

Here, we report the preparation and characterization of several

hexakis(azolylmethylphenoxy)cyclotriphosphazenes having different number of nitrogen

atoms in the azole ring and all three isomers of hexakis(pyridinoxy)

cyclotriphosphazenes. Furthermore, the thermal analysis of all the compounds was also

carried out, and thereby their degradation behavior will be compared. While this work

was in progress, one of these compounds, hexakis[4-(1H-pyrazol-1-

ylmethyl)phenoxy]cyclotriphophazene (II-4), was synthesized by Wang and co-workers

using a method different from ours.94

64

2.2 Results and Discussion

2.2.1. Synthesis and Characterization of Starting Materials

Compounds II-1, II-2 and II-3 (Figure 2-1) were synthesized as starting materials

for the synthesis of compounds II-4, II-5, and II-6, respectively, according to a literature

procedure without the use of solvents.95 In that, 4-hydroxybenzylalcohol and the

corresponding azole were heated in a 1:1 ratio for 30 minutes giving water as a

byproduct (Scheme 2-1). The condensation is found to undergo via the intermediate, p-

methylenequinone shown in Scheme 2-2 based on previous work.96

II-1 II-2 II-3

Figure 2-1. Structures of compounds II-1, II-2 and II-3.

II-1: X=Y=Z=C; R=H II-2: X=C, Y=N, Z=C; R=H II-3: X=N, Y=N, Z=C; R=CH3 Scheme 2-1. Condensation reaction between azole and 4-hydroxybenzylalcohol to

obtain compounds II-1, II-2 and III-3.

+

OH

OH

155 °C

30 min

OH

NN

N

OH

N

NN

N

OH

NN

+ H2O X

Y ZN

NH

R

OH

NX Y

ZN

R

65

OH

N

NN

N

OH

N

NN

N

(a)

(b)

(II-3b)

(II-3a)N

N NNH

CH2

O

p-methylenequinone

O

O

H

H

Scheme 2-2. Proposed mechanism of the synthesis of compounds II-3a and II-3b

X-ray structures of compounds II-1 and II-2 were also obtained (Figure 2-2).

Colorless crystals of II-1 were obtained by slow evaporation from a concentrated solution

of dichloromethane whereas crystals of II-2 were grown from a concentrated solution of

tetrahydrofuran. There are two isomeric forms of II-3 (Scheme 2-2) which form because

5-methyltetrazole has two basic nitrogen atoms. The 1H NMR spectrum of the unpurified

II-3 shows the two sets of resonances (Figure 2-4). The protons of -CH2 group clearly

shows two resonances at 5.49 and 5.71 ppm. The presence of the two isomers was

confirmed by the single crystal X-ray diffraction. The two forms of II-3 can be partially

separated. Colorless crystals of II-3a were obtained by slow evaporation from a

concentrated solution of acetone whereas crystals of II-3b were grown from a

concentrated solution of dichloromethane (Figure 2-3).

66

Figure 2-2. Thermal ellipsoid plots of the crystal structures of II-1 (left) and II-2 (right). Thermal ellipsoids are drawn at 50% probability. Hydrogen atoms have been omitted for clarity. Figure 2-3. Thermal ellipsoid plots of the crystal structures of II-3a (left) and II-3b (right). Thermal ellipsoids are drawn at 50% probability. Hydrogen atoms have been omitted for clarity.

67

II-3

b

OH

N N

N

N

OH

N

N

N

N

II-3

a

Figure 2-4. 1H NMR spectrum of a mixture of compounds II-3a and II-3b in d6-DMSO.

68

2.2.2. Synthesis and Characterization of Hexakis(azolylmethylphenoxy) cyclotriphosphazenes

The azolylmethylphenoxide anion, ROӨ is prepared from the azolylmethylphenol,

ROH in dry THF in the presence of a strong base such as KH giving hydrogen gas as a

byproduct (eq 2-1). Replacement of all chlorine atoms in [PCl2N]3 is carried out from the

direct nucleophilic substitution of the azolylmethylphenoxide anions (eq 2-2).41

ROH + KH ROӨ K⊕ + H2 (g) (2-1)

ROӨ K⊕ + [PCl2N]3 [P(OR)2N]3 + KCl (s) (2-2)

The synthesis of azolylmethylphenoxy cyclotriphosphazenes using this procedure did not

go to completion even at elevated temperatures, but they were found to undergo complete

substitution with the use of the phase transfer catalyst (PTC) tetramethylammonium

bromide, which was found to give the desired products in high yields within a short time

(Scheme 2-3).97 It has been reported that when an aryloxide has poor solubility in

solvents like tetrahydrofuran, phase transfer reagents or crown ethers and elevated

temperatures should be used to promote complete substitution. Therefore, PTC is used to

increase the lyophilicity and nucleophilicity of the oxyanions.98 In substitution reactions

of [PCl2N]3 the reaction medium should be a good solvent for the [PCl2N]3 and the

nucleophile but a poor solvent for the side products, such as potassium chloride in the

case where the base is potassium hydride. The driving force for the complete substitution

is the precipitation of side products from the solution. If this requirement is not met,

incomplete replacement of the halogen atoms may occur. In addition, the substitution of

69

bulky side groups may require forcing reaction conditions for the complete

substitution.38,98

Where R is

R = Pyrazol 1,2,4-triazol 5-methyltetrazol

II-4 II-5 II-6

Scheme 2-3. General synthetic route of hexakis(azolylmethylphenoxy) cyclotriphosphazenes

The general synthetic route of II-4, II-5 and II-6 is depicted in Scheme 2-3. In

contrast to the direct substitution procedure developed in our lab, the reported alternative

synthesis of II-4 has been carried out in a multi-step process starting from [PCl2N]3 and

substituting [PCl2N]3 by 4-formylphenoxy followed by reduction to 4-

hydroxymethylphenoxy in the presence of NaBH4.99 Next, it was converted to 4-

PN

PNP

N

O O

O

O

O

O

R

R

R

R

R

R

OH

R

N

N

NN

NN

N

NN

2. [PCl2N]3, Reflux

1. KH, Me4N⊕

BrӨ, Et3N, THF, RT

70

bromomethylphenoxy and finally reacted with pyrazole to yield the desired product.94

Compared to the procedure described above, the synthetic procedure we used undergo the

same substitution in two steps starting from compound II-1 to obtain high yields in a

shorter time. A higher yield of compound II-5 (90%) was obtained even at room

temperature compared to the synthesis of II-4 and II-6. In the synthesis of II-6, a mixture

of II-3a and II-3b were used without separation. The purpose of adding triethylamine

into the reaction mixture was to neutralize any HCl formed during the reaction.100

The complete substitution can easily be confirmed through NMR spectroscopy.

Figure 2-5 and Figure 2-6 show the 1H NMR spectra of the starting material, compound

II-2 and its substituted trimer, compound II-5 respectively. In Figure 2-5, OH peak of

II-2 shows up at 9.50 ppm and in Figure 2-6, that peak has disappeared confirming the

complete substitution. All azolylmethylphenoxy compounds show a singlet peak in 31P

NMR, and they are depicted in Table 2-1 and Figure 2-7.Compared to [PCl2N]3 which

shows up at 20.6 ppm, compounds II-4, II-5 and II-6 each shows a resonance shifted up-

field. In comparison among the azolylmethylphenoxy cyclotriphosphazenes, the more N

atoms in cyclic azoles, the further it shifts up-field.

31P NMR of [PCl2N]3 was always run in deuterated chloroform and not in DMSO like the

substituted trimers. This is because it has been found that [PCl2N]3 undergoes

degradation reactions with DMSO to yield partially or fully substituted phosphazenes.101

71

Figure 2-5. 1H NMR spectrum of compound II-2 in d6-DMSO.

72

Figure 2-6. 1H NMR spectrum of compound II-5 in d6-DMSO.

73

100 90 80 70 60 50 40 30 20 10 0 -10 -20 -30

[PCl2N]3

Compound II-5

Compound II-6

Compound II-4

Chemical shift (ppm)

Figure 2-7. 31

P NMR spectra showing the chemical shift variation of [PCl2N]3 in CDCl3,

compound II-4 (d6-DMSO), compound II-5 (d6-DMSO), and compound II-6 (d6-

DMSO).

Compounds Chemical Shift (δ), ppm

II-4 9.9

II-5 9.8

II-6 9.6

Table 2-1. 31

P NMR chemical shifts of hexakis(azolylmethylphenoxy)

cyclotriphosphazenes.

2.2.3 Synthesis and Characterization of Hexakis(pyridinoxy)cyclotriphosphazenes

The same approach as in Scheme 2-3 was applied to the synthesis of

cyclotriphosphazenes with pyridinoxy derivatives. The three pyridinols are deprotonated

with a strong base to give the nucleophile which then substitutes the chlorine atoms of

[PCl2N]3 (Scheme 2-4) to give II-7, II-8 and II-9. The synthesis of these compounds has

74

already been reported.102,103 But in the synthesis in Scheme 2-4, the use of the phase

transfer catalyst tetramethylammonium bromide led to higher yields of substituted

pyridinols in a shorter time compared to the literature procedures. The yields of II-7, II-

8 and II-9 were 91%, 90% and 93%, respectively. 31P NMR spectra of all pyridinoxy

substituted cyclic trimers were singlets (Table 2-2 and Figure 2-8). Their chemical shifts

are up-field compared to [PCl2N]3, the same trend observed with the

azolylmethylphenoxy trimers.

R-OH

R =

II-7 II-8 II-9

Scheme 2-4. Synthesis of compounds II-7, II-8 and II-9 from the pyridinols

Table 2-2. 31P NMR chemical shifts of hexakis(pyridinoxy)cyclotriphosphazenes.

Compounds Chemical Shift (δ), ppm II-7 7.5 II-8 11.0 II-9 8.3

1. KH, Me4N⊕

BrӨ, Et3N, THF, RT

2. [PCl2N]3, Reflux, ~1 d

NN N

PN

PNP

N

O O

O

O

RR

R

RO

R

R O

75

100 90 80 70 60 50 40 30 20 10 0 ‐10 ‐20 ‐30

[PCl2N]3

Compound II-8

Compound II-9

Compound II-7

Chemical shift (ppm) Figure 2-8. 31P NMR spectra showing the chemical shift variation of [PCl2N]3 in CDCl3, (compound II-7 (d6-DMSO), compound II-8 (d6-DMSO), and compound II-9 (d6-DMSO). 2.2.4. X-ray Structural Characterization of Hexakis(azolylmethylphenoxy) and Hexakis(pyridinoxy) cyclotriphosphazenes

The structural characterization of fully substituted cyclotriphosphazenes was

carried out using single crystal X-ray diffraction studies. Crystal structures were obtained

for all the azolylmethylphenoxy cyclotriphosphazenes, except for compound II-6. All

structures bear six azolylmethylphenoxy derivative side groups. The crystal structures of

these compounds are shown in Figures 2-9 - 2-13.

76

.

Figure 2-9. Thermal ellipsoid plot of the crystal structure of II-4. Thermal ellipsoids are drawn at 50% probability. Hydrogen atoms have been omitted for clarity.

Colorless crystals of compound II-4 were grown from a concentrated solution of

ethanol. The structure of this compound was solved to an R factor of 0.0436 in space

group P-1. The crystal structure is shown in Figure 2-9. The P-N and P-O bond distances

range from 1.5706(19) to 1.5882(19) and 1.5765(17) to 1.5931(16) Å, respectively. The

N-P-N ring angle has an average of 117.75(10)° and the P-N-P ring angle of

121.14(12)°.

Figure 2-10. Thermal ellipsoid plot of the crystal structure of II-5. Thermal ellipsoids are drawn at 50% probability.Hydrogen atoms have been omitted for clarity.

77

The colorless crystals of compound II-5 were grown from a concentrated solution

of DMSO/THF. The structure of this compound was solved to an R factor of 0.0598 in

space group P-1. The crystal structure is shown in Figure 2-10. The P-N and P-O bond

lengths have an average of 1.580(3) and 1.586(2) Å respectively. The N-P-N angles vary

from 117.33(14) to 117.73(14)°, and the P-N-P angles vary from 120.56(16) to

122.49(16)°. Colorless crystals of compound II-7 were grown from the slow evaporation of a

solution of concentrated acetone. The structure of compound II-7 (Figure 2-11) was

solved to an R factor of 0.0273 in space group Pna2(1). The P-N and P-O bond length

have an average of 1.5773(18) and 1.5919(13) Å respectively. The average N-P-N angle

is 118.44(11) with individual angles of 118.03(10), 119.20(9) and 118.08(9) °. The P-N-P

ring angles have an average of 121.30(11) Å.


The structure of compound II-8 (Figure 2-12) was solved to an R factor of 0.0466

in space group P2(1)/c. The P-N and P-O bond length have an average of 1.578(2) and

1.5838(17) Å respectively. The average N-P-N angle is 117.34(11) with individual

78

angles of 117.39(11), 117.17(11) and 117.46(11)°. The P-N-P ring angles have an

average of 122.19(13) Å.


Colorless crystals of compound II-9 were grown from methanol and the structure

of this compound was solved to an R factor of 0.0470 in space group C2/c. The structure

is shown in Figure 2-13. The N-P-N ring angle has range from 116.47(16) to

117.73(12)° and the P-N-P ring angle vary from 121.58(18) to 122.47(13)°. The P-N and

P-O bond lengths vary from 1.578(2) to 1.584(2) and 1.5803(17) to 1.5956(18) Å

respectively.


79

From these crystallographic data, it can be summarized that in all of these

azolylmethylphenoxy and pyridinoxy trimers, the N3P3 has a very slightly puckered ring

as seen with [PCl2N]3.103 All the rings have same dimensions in terms of bond length and

bond angle. In all substituted trimers, the P-N bond distances, the bond angles of N-P-N,

and P-N-P are very close to those found in other cyclic phosphazenes. The P-N bond

distances of the substituted trimers are within the bond distances of [PCl2N]3, which is

1.47-1.62 Å. The N-P-N and P-N-P bond angles are also comparable to the bond angles

found in trimer, which is ~ 120 ° for N-P-N and 117-125 Å for P-N-P bond angle.101 The

average bond length of P-O bond, O-P-O angle, and the P-O-C angles are the typical

values which are found in cyclic aryloxyphosphazenes.104

2.2.5. Thermal Analysis of Hexakis(azolylmethylphenoxy) and Hexakis(pyridinoxy) cyclotriphosphazenes

Thermal stability of the hexasubstituted azolylmethylphenoxy and

pyridinoxyphosphazene trimers was studied by thermogravimetric analysis (TGA).

Thereby the thermal degradation occurring via weight loss was determined. All the scans

were run at 10 °C/min under both air and inert (N2) atmosphere. Inert and air atmosphere

thermograms of all the azolylmethylphenoxy and pyridinoxy trimers are depicted in

Figures 2-14 and 2-15 respectively. All azolylmethylphenoxy trimers exhibit a several

steps of weight losses in both inert and air atmosphere which can be clearly seen from

their derivative thermograms. Figure 2-16 shows the derivatogram for compound II-6,

with several weight losses.

However, what is interesting is the TGA curves of pyridinoxy trimers. When

compounds II-7 and II-9 follow the same pattern with several steps compound II-8

80

exhibits one sharp weight loss though all three compounds differ only from the position

of N atom on the ring. TGA curve for compound II-8 which shows a one-step

degradation is shown in Figure 2-17 along with its derivatogram (DTG) whereas Figure

2-18 depicts the thermogram and derivatogram of compounds II-7 in which it shows a

three-step decomposition. This several steps of weight loss arises due to the loss of

different species with increasing temperature.105 Degradation temperatures and associated

parameters obtained from these thermograms are summarized in Table 2-4. D0.05

indicates the initial decomposition temperature (IDT) at which 5% decomposition occurs

and D1/2 represents the temperature at which 50% of decomposition occurs. The

maximum rate of decomposition temperature is denoted as MRDT.105 It can be seen from

the Table 2-3, that compound II-5 shows a good thermal stability as D0.05 value. In inert

atmosphere it was 355 °C whereas in air atmosphere it was 351 °C. Decomposition

temperature at half way, D1/2 was not reported in both inert and air atmosphere for the

temperature applied, which was 600 °C except for compounds II-7 and II-8 in inert

atmosphere and compounds II-7 and II-9 in air atmosphere. Residue obtained after the

complete decomposition of all trimers found to have the highest residue percentage for

compound II-5, which was 71 wt.% in inert atmosphere and 70 wt.% at air atmosphere.

The MRD value 19 %/min at 296 °C for compound II-7 was which was found to be the

highest in air atmosphere whereas it was 16 %/min at 370 °C for compound II-8 in inert

atmosphere.

Generally, 5% decomposition of all compounds in both inert and air atmosphere

is not that significantly different and they do not follow a certain order.

81

It is necessary to run TGA/MS such as pyrolysis/FTMS in order to determine the

fragments lost as we increase the temperature.106

By analyzing the leftover residue by EA,

it is also possible to determine the composition of the residue.105,107

Figure 2-14. Inert atmosphere thermogravimetric analysis of azolylmethylphenoxy and

pyridinoxy trimers.

82

Figure 2-15. Air atmosphere thermogravimetric analysis of azolylmethylphenoxy and

pyridinoxy trimers.

Figure 2-16. Inert atmosphere thermogram and derivatogram of compound II-6.

83



84

CompoundD 0.05 D 1/2 D 0.05 D 1/2 Inert

Compound II-4 247 - 427 226 - 360 58 61Compound II-5 355 - 362 351 - 371 72 70Compound II-6 255 - 346 260 - 340 58 58Compound II-7 278 393 299 278 424 296 34 41Compound II-8 322 384 370 320 - 350 44 60Compound II-9 279 - 360 228 426 384 60 36

Inert atmosphere (°C) Air atmosphere (°C) Residue analysis (%)MRDT MRDT Air

Table 2-3. Inert and air atmosphere TGA parameters of azolylmethylphenoxy and pyridinoxy trimers.

2.3 Conclusion

A series of new hexakis(azolylmethylphenoxy)cyclotriphosphazenes—azoles

being pyrazole, 1,2,4-triazole, and 5-methyltetrazole—have been synthesized. Along with

them, all three isomers of hexakis(pyridinoxy)cyclotriphosphazenes have also been

resynthesized using an approach slightly different to the literature procedure via

nucleophilic substitution in the presence of KH as a strong base. In synthesizing all of

these compounds, PTC was applied for a complete substitution. All cyclic compounds

were studied by a combination of NMR, ESI-MS, EA, FTIR spectroscopy, and single-

crystal X-ray diffraction. Furthermore, their thermal degradation was studied by TGA in

both inert and air atmosphere.

2.4 Experimental

2.4.1 General Considerations

Standard Schlenk techniques were used with all manipulations dealing with

potassium hydride and all reactions were carried out under nitrogen atmosphere. The

compound [PCl2N]3, purchased from Aldrich, was stored in an inert-atmosphere

glovebox. Triethylamine was also purchased from Aldrich. Pyrazole, 1,2,4-triazole, 5-

85

methyltetrazole, 2-hydroxypyridine, 3-hydroxypyridine and 4-hydroxypyridine were

purchased from TCI America Company. Tetramethylammonium bromide was purchased

from Eastman Kodak company. Potassium hydride in mineral oil purchased from Aldrich

was filtered and washed with dry THF and stored in a glovebox. Tetrahydrofuran was

dried and deoxygenated by alumina column in the Pure SolvTM solvent system

(Innovative Technologies, Inc). All other reagents were used without further purification.

NMR spectra were recorded on a Varian Gemini 300 MHz instrument using deuterated

DMSO and CDCl3 as NMR solvents. The 1H and 13C NMR spectra were referenced

relative to the resonances of deuterated solvent. The 31P NMR spectra were referenced

with external H3PO4 at δ 0 ppm. IR spectra were collected with a Bomem Excalibur

Series with FTS 3000 model FTIR Spectrometer. Unless otherwise stated the spectra

were recorded on pure compounds. All FTIR samples used were a mixture of sample (1

mg) ground with Thermo Spectra-Tech KBr powder (100 mg). All samples were vibrated

by a Schwingmuble vibrating mill for 20 seconds. Melting points were measured using a

Fluke Electrothermal MEL-TEMP® connected to a digital thermometer (Model 51 II).

Mass spectrometric analysis using electrospray ionization (ESI) technique was performed

using a Bruker Esquire-LC ion trap mass spectrometer by Dr. Bethany Subel and

Vincenzo Scionti in the Department of Chemistry at The University of Akron. Elemental

analysis and ICP analysis were performed by University of Illinois Microanalytical

Laboratory. Crystal structure data were collected and solved by Dr. Matthew J. Panzner

and Brian D. Wright in the Department of Chemistry at The University of Akron. Thermo

Gravimetric Analysis was done by a QSeries – [Q500 – 0882 – TGA Q500@Mfg – tga]

86

TGA instrument at a scanning rate of 10 °C/min under N2 and air atmosphere in the

Department of Polymer Science and Polymer Engineering at The University of Akron.

2.4.2 X-ray Crystallographic Structure Determination Details

Crystals of compounds II-3,II-4, II-5, II-7,II-8 and II-9 were coated in paratone

oil and mounted on a CryoLoop™ and placed on the goniometer head under a stream of

nitrogen cooled to 100 K.108 For all except the crystals of II-1, II-2 and II-7, X-ray data

were collected on a Bruker Apex CCD diffractometer with graphite-monochromated Mo

K∝ radiation (λ = 0.71073 Å) whereas X-ray data for II-1, II-2 and II-7 were collected

on a Bruker Kappa APEX II Duo CCD diffractometer with a Cu ImuS micro-focus

source with QUAZAR optics (1.54178 Å). The unit cell was determined by using

reflections from three different orientations.The data were integrated using SAINT.An

empirical absorption correction and other corrections were applied to the data using

multi-scan SADABS. Structure solution, refinement, and modeling were accomplished

by using the Bruker SHELXTL package.109 The structures were obtained by full-matrix

least-squares refinement of F2 and the selection of appropriate atoms from the generated

difference map.

2.4.3 Synthesis of 4-(1H-pyrazol-1-ylmethyl)phenol (II-1)

A mixture of pyrazole (6.9 g, 0.10 mol) and 4-hydroxybenzyl alcohol (12.4 g,

0.100 mol) was heated to 155 °C and intensively stirred for 30 min. The resultant yellow

solid was cooled, powdered, and thoroughly washed with cold ethanol and dried in air.

Yield: 8.88 g, 51.0 mmol, 51 %. Mp: 109 °C. Anal. Calc. for C10H10N2O: C, 68.95; H,

87

5.79; N, 16.08. Found: C, 68.96; H, 5.71; N, 15.01. ESI-MS (m/z): calcd for C10H10N2O

[M + H] + 175.2. Found 175.0. 1H NMR (300 MHz, DMSO- d6): δ 5.17 (s, 2H, C-(CH2)-

N), 6.23 (s, 1H, C=C(H)C), 6.71 (d, 2H, J = 8.09 Hz, CC-C(H)-CH), 7.13 (d, 2H, J =

8.09 Hz, OC-C(H)-CH)), 7.42 (s, 1H, N-C(H)C=C), 7.72 (s, 1H, N=C(H)C), 9.40 (s, 1H,

C- OH). 13C {1H} NMR (75 MHz, DMSO- d6): δ 156.9, 138.7, 129.6, 129.1, 127.8,

115.2, 105.3, 54.3.

X-ray crystal structure analysis of II-1: formula C10H10N2O, Mw = 174.20,

colorless crystal 0.45 x 0.19 x 0.14 mm3, a = 7.8400(18) Å, b = 11.148(3) Å, c =

20.680(5) Å, α = 90°, β = 95.647(3)°, γ = 90°. T = 273(2) K, Z = 8, monoclinic, space

group Pc, V = 1798.6(7) Å3, Dcalc = 1.287 Mg.m-3, λ = 0.71073 Å, μ = 0.086 mm-1,

13095 reflections collected, 7017 independent (Rint = 0.0638), 473 refined parameters,

R1/wR2 (I>2σ(I)) = 0.0688/0.1744 and R1/wR2 (all data) = 0.0719/0.1814 , maximum

(minimum) residual electron density 0.629 (-0.267) e. Å-3.

2.4.4 Synthesis of 4-(1H-1,2,4-triazol-1-ylmethyl)phenol (II-2)

The same procedure that was used to synthesize the compound II-1 was applied

to a mixture of 1,2,4-triazole (6.9 g, 0.10 mol) and 4-hydroxybenzyl alcohol (12.4 g,

0.100 mol). Yield: 13.1 g, 75.0 mmol, 75 %. Mp: 145 °C. Td: 192 °C. Anal. Calc. for

C9H9N3O: C, 61.70; H, 5.18; N, 23.99. Found: C, 61.61; H, 5.13; N, 23.48. ESI-MS

(m/z): calcd for C9H9N3O [M + Na] + 198.2. Found 198.1. 1H NMR (300 MHz, DMSO-

d6): δ 5.26 (s, 2H, C-(CH2)-N), 6.73 (d, 2H, J = 8.99 Hz, CC-C(H)-CH), 7.13 (d, 2H, J =

8.99 Hz, OC-C(H)-CH)), 7.95 (s, 1H, N=C(H)N), 8.58 (s, 1H, N=C(H)N), 9.51 (s, 1H, C-

88

OH). 13C {1H} NMR (75 MHz, DMSO- d6): δ 157.2, 151.6, 143.8, 129.5, 126.5, 115.3,

51.8.

X-ray crystal structure analysis of II-2: formula C9H9N3O, Mw = 175.19,


18.2326(17) Å, α = 90°, β = 90, γ = 90°. T = 100(2) K, Z = 4, orthorhombic, space group

Pca2(1), V = 847.09(14) Å3, Dcalc = 1.374 Mg.m-3, λ = 1.54178 Å, μ = 0.773 mm-1,


R1/wR2 (I>2σ(I)) = 0.0253/0.0665 and R1/wR2 (all data) = 0.0253/0.0665, maximum

(minimum) residual electron density 0.120 (-0.165) e. Å-3.

2.4.5 Synthesis of 4-(1H-5-methyltetrazol-1-ylmethyl)phenol (II-3)

A mixture of 5-methyltetrazole (8.40 g, 100 mmol) and 4-hydroxybenzyl alcohol

(12.4 g, 100 mmol) were heated together as described for the synthesis of II-1. Crystals

suitable for single X-ray diffraction were grown separately from acetone and

dichloromethane. Yield: 12.1 g, 64.0 mmol, 63 %. Mp: 137-138 °C. Anal. Calc. for

C9H10N4O: C, 56.83; H, 5.30; N, 29.46. Found: C, 56.85; H, 5.20; N, 28.80. ESI-MS

(m/z): calcd for C9H10N4O [M + Na]+ 213.2. Found 213. 0. 1H NMR (300 MHz, DMSO-

d6): δ 2.57 (s, 3H, C-CH3), 5.56 (s, 2H, C-(CH2)-N -major isomer), 5.77 (s, 2H, C-(CH2)-

N -minor isomer), 6.83 (d, 2H, J = 8.99 Hz, CC-C(H)-CH- major isomer), 7.20 (d, 2H, J

= 8.99 Hz, OC-C(H)-CH)-major isomer), 7.28 (d, 2H, J = 8.99 Hz, OC-C(H)-CH)-minor

isomer), 9.65 (s, 1H, C-OH). 13C {1H} NMR (75 MHz, DMSO- d6): δ 157.5, 151.8, 130.1

(minor isomer), 129.5, 124.7, 115.6, 49.5, 8.4.

89

X-ray crystal structure analysis of II-3a: formula C9H10N4O, Mw = 190.21,

colorless crystals 0.34 x 0.19 x 0.05 mm3, a = 8.933(3) Å, b = 9.818(3) Å, c = 10.736(4)

Å, α = 82.468(5)°, β = 77.736(5)°, γ = 81.594(5)°. T = 100(2) K, Z = 4, triclinic, space

group P-1, V = 905.3(5) Å3, Dcalc = 1.396 Mg.m-3, λ = 0.71073 Å, μ = 0.969 mm-1, 7080

reflections collected, 3682 independent (Rint = 0.0417), 257 refined parameters, R1/wR2

(I>2σ(I)) = 0.0659/0.1581 and R1/wR2 (all data) = 0.0844/0.1677, maximum (minimum)

residual electron density 0.472(-.281) e. Å-3.

X-ray crystal structure analysis of II-3b: formula C9H10N4O, Mw = 190.21,

colorless crystals 0.32 x 0.10 x 0.10 mm3, a = 7.401(2) Å, b = 16.035(4) Å, c = 8.239(2)

Å, α = 90°, β = 104.841(5)°, γ = 90°. T = 100(2) K, Z = 4, monoclinic, space group

P2(1)/c, V = 945.1(4) Å3, Dcalc = 1.337 Mg.m-3, λ = 0.71073 Å, μ = 0.093 mm-1, 7349

reflections collected, 1915 independent (Rint = 0.0363), 129 refined parameters, R1/wR2

(I>2σ(I)) = 0.0391/0.1028 and R1/wR2 (all data) = 0.0507/0.1069, maximum (minimum)

residual electron density 0.268(-0.171) e. Å-3.

2.4.6 Synthesis of Hexakis[4-(1H-pyrazol-1-ylmethyl)phenoxy]cyclotriphophazene (II-4) Potassium hydride (0.082 g, 2.05 mmol) and tetramethylammonium bromide

(0.90 mg, 0.0058 mmol) were weighed into a Schlenk flask inside the dry box and

dissolved in dry THF (15 mL) and hexachlorocyclotriphosphazene (0.088 g, 0.254 mmol)

dissolved in dry THF (20 mL) was added. 4-(1H-pyrazol-1-ylmethyl)phenol, II-1 (0.357

g, 2.05 mmol) dissolved in 20 mL of dry THF was added dropwise to the reaction

mixture under N2 purge. After 30 min, 0.2 mL of triethylamine was added dropwise. The

reaction mixture was stirred at room temperature for 2 days followed by refluxing at 80

90

°C for an additional day under N2 purge. The solid that remained inside the flask was

filtered using Celite® and washed with additional THF (20 mL). The volatiles were

removed in vacuo to a small volume (~1 mL) and a yellow sticky solid was formed by

the addition of water (100 mL). The suspension was stirred at room temperature for an

hour and the sticky solid was isolated by decanting the liquid. The yellow solid was dried

on the oven at 110 °C overnight, was powdered and it was washed with diethyl ether (70

mL) and dried in the air. Crystals suitable for single X-ray diffraction were grown from

ethanol. Yield: 0.269 g, 0.229 mmol, 90 %. Mp:128 °C. Anal. Calc. for C60H54N15O6P3:

C, 61.38; H, 4.64; N, 17.89, P, 7.91. Found: C, 60.87; H, 4.53; N, 16.55, P, 7.75. ESI-

MS (m/z): calcd for C60H54N15O6P3 [M+H+] 1175.1. Found 1174.4. FTIR (KBr, cm-1):

1507 (C-C,Ph),1178 ( P=N), 964 (P-O-Ph). 1H NMR (300 MHz, DMSO- d6): δ 5.31 (s,

2H, C-(CH2)-N), 6.29 (s, 1H, C=C(H)C), 6.73 (d, 2H, J = 8.39 Hz, CC-C(H)-CH), 7.05

(d, 2H, J = 8.39 Hz, OC-C(H)-CH)), 7.50 (s, 1H, N-C(H)C=C), 7.81 (s, 1H, N=C(H)C).

13C {1H} NMR (75 MHz, DMSO- d6): δ 149.0, 139.2, 134.7, 130.2, 128.9, 120.5, 105.5,

53.9. 31P{1H} NMR (121 MHz, DMSO- d6): δ 9.9.

X-ray crystal structure analysis of II-4: formula C60H54N15O6P3, Mw = 1174.09,


20.111(2) Å, α = 89.554(2)°, β = 82.848(2)°, γ = 85.779(2)°. T = 100(2) K, Z = 2,

triclinic, space group P-1, V = 2767.9(5) Å3, Dcalc = 1.409 Mg.m-3, λ = 0.71073 Å, μ =

0.177 mm-1, 19613 reflections collected, 11004 independent (Rint = 0.0381), 757 refined

parameters, R1/wR2 (I>2σ(I)) = 0.0436/0.0971 and R1/wR2 (all data) = 0.0759/0.1124,

maximum (minimum) residual electron density 0.321(-0.398) e. Å-3.

91

2.4.7 Synthesis of Hexakis[4-(1H-1,2,4-triazol-1-ylmethyl)phenoxy]cyclotriphophazene (II-5) Potassium hydride (0.34 g, 8.56 mmol) and tetramethylammonium bromide (2.73

mg, 0.018 mmol) were weighed into a Schlenk flask and dissolved in dry THF (30 mL)

and a solution of hexachlorocyclotriphosphazene (0.37 g, 1.06 mmol) dissolved in dry

THF (20 mL) was added. 4-(1H-1,2,4-triazol-1-ylmethyl)phenol, II-2 (1.5 g, 8.56 mmol)

dissolved in 35 mL of dry THF was added dropwise to the reaction mixture. After 30

min, 0.75 mL of triethylamine was added. The reaction mixture was stirred at room

temperature for additional 20 h under N2 purge. The white solid was filtered using

Celite® and washed with THF (20 mL). The volatiles were removed in vacuo to a small

volume (~1 mL) and a white solid was formed by the addition of water (100 mL). The

suspension was stirred at room temperature for an hour and the white solid was filtered

and dried at 110 °C. The solid was washed with diethyl ether (30 mL), filtered and dried

in air. Crystals suitable for X-ray diffraction were grown from a solution of DMSO/THF.

Yield: 1.13 g, 0.96 mmol, 90 %. Mp: 135-137 °C. Anal. Calc for C54H48N21O6P3 : C,

54.96; H, 4.10; N, 24.93, P, 7.87. Found: C, 54.06; H, 3.99; N, 23.76, P, 6.89. ESI- MS

(m/z): calcd for C54H48N21O6P3 [M+Na+] 1203.0. Found 1202.8. FTIR (KBr, cm-1): 1507

(C-C,Ph),1174 ( P=N), 959 (P-O-Ph). 1H NMR (300 MHz, DMSO- d6): δ 5.40 (s, 6H, C-

(CH2)-N), 6.77 (d, 12H, J = 8.99 Hz, CC-C(H)-CH), 7.12 (d, 12H, J = 8.99 Hz, OC-

C(H)-CH), 8.02 (s, 6H, N=C(H)N), 8.67 (s, 6H, N=C(H)N). 13C {1H} NMR (75 MHz,

DMSO- d6): δ 151.9, 149.2, 144.4, 133.3, 129.3, 120.6, 51.3. 31P{1H} NMR (121 MHz,

DMSO- d6): δ 9.8.


colorless crystal 0.27 x 0.16 x 0.04 mm3, a = 8.694(3) Å, b = 16.149(6) Å, c = 20.924(7)

92

Å, α = 111.030(6)°, β = 98.615(6)°, γ = 96.147(6)°. T = 100(2) K, Z = 2, triclinic, space

group P-1, V = 2669.7(16) Å3, Dcalc = 1.468 Mg.m-3, λ = 0.71073 Å, μ = 0.186 mm-1,



(minimum) residual electron density 0.355(-0.413) e. Å-3.

2.4.8 Synthesis of Hexakis[4-(1H-5-methyltetrazol-1-lmethyl)phenoxy] cyclotriphophazene (II-6) The synthesis of compound II-6 was also carried out using the same steps that are

described in compound II-4 and II-5. In a 150 mL Schlenk flask, KH (0.16 g, 3.95

mmol) and tetramethylammonium bromide (1.26 mg, 0.0082 mmol) were dissolved in

dry THF (30 mL). Hexachlorocyclotriphosphazene (0.17 g, 0.49 mmol) dissolved in dry

THF (20 mL) was added. 4-(1H-5-methyltetrazol-1-ylmethyl)phenol, II-3 (0.75 g, 3.95

mmol) dissolved in 35 mL of dry THF was added dropwise. After 30 min, 0.35 mL of

triethylamine was added. The reaction mixture was refluxed at 80 °C for 24 h under

nitrogen purge. The white solid, presumably the salts formed during the reaction, was

filtered using Celite® and washed with THF (20 mL). After the removal of volatiles to a

small volume (~1 mL), water (100 mL) was added and a yellow oily product was

obtained. Water suspension was stirred at room temperature for an hour. Water was

decanted, and the product was dried on the oven overnight to yield a solid. The solid was

crushed with a spatula stirred with diethyl ether (30 mL) for 4 hours. The white powder

was filtered and dried in air. Yield: 0.50 g, 0.39 mmol, 80 %. Mp: 78-80 °C. Anal. Calc.

for C54H54N27O6P3 : C, 51.06; H, 4.29; N, 29.78, P, 7.32. Found: C, 52.52; H, 4.32; N,

27.73, P, 6.24. ESI- MS (m/z): calcd for C54H54N27O6P3 [M + Na] + 1293.1. Found

93

1293.1. FTIR (KBr, cm-1): 1507 (C-C,Ph),1164 (P=N), 955(P-O-Ph). 1H NMR (300

MHz, DMSO- d6): δ 2.42 (s, 3H, C-CH3), 5.61 (s, 2H, C-(CH2)-N -major isomer), 5.86

(s, 2H, C-(CH2)-N -minor isomer), 6.85 (d, 2H, J = 8.99 Hz, CC-C(H)-CH- major

isomer), 7.16 (d, 2H, J = 8.99 Hz, OC-C(H)-CH)-major isomer), 7.23 (d, 2H, J = 8.99

Hz, OC-C(H)-CH)-minor isomer). 13C {1H} NMR (75 MHz, DMSO- d6): δ 180.7, 152.2,

131.6, 129.5, 120.9, 89.2, 65.0, 48.9, 8.4. 31P{1H} NMR (121 MHz, DMSO- d6): δ 9.6.

2.4.9 Synthesis of Hexakis(2-pyridinoxy)cyclotriphosphazene (II-7)

Potassium hydride (0.84 g, 21.03 mmol) and tetramethylammonium bromide

(9.00 mg, 0.058 mmol) were weighed inside the glovebox into a Schlenk flask and dry

THF was added (20 mL). [PCl2N]3 (0.91 g, 2.60 mmol) dissolved in dry THF (20 mL)

was slowly added under N2 purge. A solution of 2-hydroxypyridine (2.0 g, 21.03 mmol)

dissolved in 35 mL of dry THF was added dropwise. After 30 min, 1.8 mL of

triethylamine was added. The reaction mixture was refluxed at 80 °C for a day under

nitrogen purge. The reaction mixture was filtered using Celite® and washed with THF (20

mL). The volatile components were removed in vacuo to a small volume (~1 mL) and a

yellow colored powder was formed by the addition of water (200 mL). The suspension

was stirred at room temperature for an hour. The yellow solid was filtered, stirred with

~100 mL diethyl ether, filtered and dried in air. Crystals suitable for X-ray diffraction

were grown from acetone. Yield: 1.66 g, 2.37 mmol, 91%. Mp: 174 °C. Anal. Calc. for

C30H24N9O6P3 : C, 51.51; H, 3.46; N, 18.02; P, 13.28. Found: C, 50.77; H, 3.18; N,

17.13; P, 13.31. ESI-MS (m/z): calcd for C30H24N9O6P3 [M + Na]+ 722.5 Found 722.1.

FTIR (KBr, cm-1): 1592 (C-C,Ph), 1183( P=N), 952 ( P-O-Ph). 1H NMR (300 MHz,

94

DMSO-d6): δ 7.07 (d, 1H, J = 8.09, C-C(H)=C), 7.19 (t, J = 8.09, C=C(H)-C), 7.78 (t, J =

8.09, C-C(H)=C), 8.14 (d, J = 8.09, C=C(H)-N). 13C {1H} NMR (75 MHz, DMSO-d6): δ

156.9, 147.8, 142.2, 121.2, 113.9. 31P {1H} NMR (121 MHz, DMSO-d6): δ 7.5 (s).


colorless crystal 0.34 x 012 x 0.07 mm3, a = 24.9148(10) Å, b = 9.6737(4) Å, c =

12.7231(5) Å, α = 90°, β = 90, γ = 90°. T = 100(2) K, Z = 4, orthorhombic, space group

Pna2(1), V = 3066.5(2) Å3, Dcalc = 1.515 Mg.m-3, λ = 1.54178 Å, μ = 2.313 mm-1,





Potassium hydride (0.84 g, 21.03 mmol) and tetramethylammonium bromide

(9.00 mg, 0.058 mmol) were weighed inside the glovebox into a Schlenk flask and dry

THF was added (20 mL). [PCl2N]3 (0.91 g, 2.60 mmol) dissolved in dry THF (20 mL)

was slowly added under N2 purge. A solution of 3-hydroxypyridine (2.0 g, 21.03 mmol)

dissolved in 35 mL of dry THF was added dropwise. After 30 min, 1.8 mL of

triethylamine was added. The reaction mixture was refluxed at 80 °C for a day under

nitrogen purge. The reaction mixture was filtered using Celite® and washed with THF (20

mL). The volatile components were removed in vacuo to a small volume (~1 mL) and a

yellow colored oily product was formed by the addition of water (200 mL). The

suspension was stirred at room temperature for an hour. Water was slowly decanted and

the solid was dried on the oven at 55 °C for 2 days to yield colorless crystals. Yield: 1.69

95

g, 2.34 mmol, 90%. Mp: 98 °C. Anal. Calc. for C30H24N9O6P3 : C, 51.51; H, 3.46; N,

18.02; P, 13.28. Found: C, 51.91; H, 3.41; N, 18.49; P, 14.44. ESI-MS (m/z): calcd for

C30H24N9O6P3[M + Na]+ 722.5. Found 721.1. FTIR (KBr, cm-1): 1576 (C-C,Ph), 1182(

P=N), 960 ( P-O-Ph). 1H NMR (300 MHz, DMSO-d6): δ 8.45 (d, 12H, J = 2.68, N=CH),

2-H arom.), 8.26 (s, OC-C(H)), 7.38 (m, J = 5.10, OC-C(H)=CH). 13C {1H} NMR (75

MHz, DMSO-d6): δ 150.0, 146.3, 142.0, 127.9, 124.8. 31P {1H} NMR (121 MHz,

DMSO-d6): δ 11.0 (s).


colorless crystal 0.33 x 017 x 0.16 mm3, a = 17.9505(19) Å, b = 22.430(2) Å, c =


group P2(1)/c, V = 3026.8(6) Å3, Dcalc = 1.535 Mg.m-3, λ = 0.71073 Å, μ = 0.259 mm-1,





Similar to the above procedure, a mixture of KH (0.42 g, 10.51 mmol) and

tetramethylammonium bromide (5.00 mg, 0.032 mmol) were dissolved in dry THF (30

mL) in a Schlenk flask. Solutions of [PCl2N]3 (0.453 g, 1.303 mmol) and 4-

hydroxypyridine (1.0 g, 10.51 mmol) dissolved in 35 mL of dry THF were added

dropwise. After 30 min, 0.90 mL of triethylamine was added and the reaction mixture

was refluxed at 80 °C for 1 day. Upon cooling, a white solid formed inside the flask,

which was filtered and washed with THF (20 mL). The volatile components were

96

removed in vacuo to a small volume and a white solid was formed by the addition of

water (100 mL). The suspension was stirred at room temperature for an hour. The white

solid was filtered and air dried overnight. The white powder was washed with diethyl

ether (30 mL), isolated by filtration and dried in air. Crystals suitable for single X-ray

diffraction were grown from THF/Et2O. Yield: 0.872 g, 1.21 mmol, 93%. Mp: 156 °C.

Anal. Calc. for C30H24N9O6P3 : C, 51.51; H, 3.46; N, 18.02; P,13.28. Found: C, 52.60; H,

3.52; N, 17.88; P, 13.21. ESI-MS( m/z) calcd for C30H24N9O6P3 [M + Na]+ 722.5. Found

721.2. FTIR (KBr, cm-1): 1579 (C-C,Ph), 1181 (P=N), 951 ( P-O-Ph). 1H NMR (300

MHz, DMSO-d6): δ 7.07 (d, 12H, J = 5.99 Hz, N-C(H)-CH), 8.50 (d, 12H, J = 5.99 Hz,

OC-C(H)-CH), 13C {1H} NMR (75 MHz, DMSO-d6 ): δ 155.8, 151.9, 115.7. 31P {1H}

NMR (121 MHz, DMSO-d6): δ 8.3 (s).


colorless crystal 0.48 x 0.45 x 0.19 mm3, a = 14.037(8) Å, b = 10.9687) Å, c =


group C2/c, V = 3022(3) Å3, Dcalc = 1.538 Mg.m-3, λ = 0.71073 Å, μ = 0.260 mm-1,




97

CHAPTER III

SYNTHESIS AND CHARACTERIZATION OF POLY(DICHLOROPHOSPHAZENE)

TO BE USED AS THE BACKBONE FOR MACROMOLECULAR SUBSTITUTION

3.1 Introduction

After the first failed attempt to synthesize soluble [PCl2N]n by Stokes in

1897,43,44 Allcock and co-workers became the pioneers in the preparation of the first

soluble linear [PCl2N]n by thermal ROP of [PCl2N]3.39,43 This discovery in the 1960s was

a major breakthrough in inorganic-backbone phosphazene chemistry due to the vast

applications possible by substituting different R groups to the phosphazene backbone.43

Although this method requires elevated temperatures, this is currently the main method to

high molecular weight polymers (Mw > 106) with relatively broad PDI (polydispersity

index), and this also remains the most widely used approach for the polymer synthesis to

date.39,110,111 Furthermore, the ring opening polymerization route provides little or no

control over the molecular weight.43

Scheme 3-1. Ring opening polymerization of [PCl2N]3 to [PCl2N]n43

P NCl

Cln

NP

NPN

PClCl

Cl Cl

ClCl250 °C

Sealed tube+ Insoluble polymer

98

The time required for the ROP depends on factors like temperature and purity of

[PCl2N]3. If heating temperature increases above 250 °C, it drastically accelerates both

the rates of polymerization and crosslinking. Reaction temperatures below 250 °C rapidly

slow the rates of polymerization, and 230 °C is found to be the lowest temperature to

carry out the uncatalyzed ROP.111 According to Allcock, the polymerization reaction

using 200 g of [PCl2N]3 requires 48 hours at 250 °C to obtain 70 % conversion to soluble

[PCl2N]n. At 300 °C, 50 % of conversion to the soluble [PCl2N]n takes place in an hour,

and within 17 minutes after that, the insoluble product starts forming. The soluble

[PCl2N]n can be depolymerized at temperatures above 350 °C to form [PCl2N]3 and other

cyclics as depicted in Scheme 3-2. This can also be achieved by heating at 200 °C under

reduced pressure.111

[PCl2N]3 + [PCl2N]4 + [PCl2N]5

Scheme 3-2. The depolymerization of [PCl2N]n above 350 °C48

The ROP of [PCl2N]3 requires a trace amount of water, however the exact

quantity needed is uncertain. Therefore, before transferring trimer into the tube, the

water- rinsed tube is always oven-baked for at least an hour. According to the studies

done by Allcock, a trace of water acts as an initiator and accelerates polymerization,

however at high concentration, it can act as an inhibitor. This is supported by the

mechanism of polymerization proposed by Emsley, which will be discussed later in this

chapter. At low concentration, water assists the ionization of chloride from P, which is a

P NCl

Cln >350 °C

Δ

k

O

fo

th

in

o

w

W

re

re

F[Phr

[P

ey step in th

OH and leads

ound to be h

he trimer wa

nert atmosph

f water. At v

water in [PCl

When more th

etarded and a

esulted.112

igure 3-1. VPCl2N]n as ars at 250 °C

Typic

PCl2N]3 in th

he reaction m

s to crosslink

igher but als

as exposed to

here. Figure

very low wat

l2N]3, increas

han 0.2 mol

at the highes

Variation in tha function of . Reproduce

ally, there ar

he melt or in

mechanism, w

ks. Accordin

so the rate of

o the atmosp

3-1 depicts t

ter concentra

sing amount

% of water

st water conc

he yield (solf water conced by permis

re two types

n solution. Ex

99

whereas a lar

ng to their stu

f polymeriza

phere, in com

the % yield o

ations, withi

ts of water in

was present,

centration (>

lid line) and entration aftesion of The

s of mechani

xcept for the

rger amount

udy, not only

ation was als

mparison to a

of polymer w

in the range

ncreased the

, the polyme

> 1%), insolu

intrinsic viser polymerizAmerican C

isms propose

e initiation st

t of water co

y the yield o

so found to o

a [PCl2N]3 st

with increasi

of 0.02 to ~

rate of poly

erization pro

uble polyme

scosity (brokzation of [PC

Chemical Soc

ed to explain

tep, both me

onverts P-Cl

of polymer w

occur faster w

tored under a

ing the amou

0.1 mol % o

ymerization.

ocess was

er often

ken line) of Cl2N]3 after ciety.111,112

n the ROP of

echanisms of

to P-

was

when

an

unt

of

15

f

f

100

ROP are similar to each other with a cationic chain growth polymerization. Emsley

proposes the protonation mechanism in which one of the nitrogens on [PCl2N]3 gets

protonated due to its basicity. This leads to the cleavage of the bond between nitrogen

and phosphorus and opens the ring leaving a lone pair on nitrogen. Next, that lone pair on

nitrogen attacks another [PCl2N]3, and the polymerization gets started. The mechanism is

shown in Scheme 3-3. According to this mechanism, the source of protons is from the

bound water to polymerization tube. Therefore, this explains the presence of traces of

water to initiate the ROP.113,114

Scheme 3-3. Mechanism of ROP of [PCl2N]3 by Emsley53,111,113,114 The second and most widely accepted mechanism for ROP has been proposed by

Allcock, which is shown in Scheme 3-4. The initiation involves the ionization of one of

the chlorides from [PCl2N]3 generating a phosphozenium cation. In the next step, a lone

+ H+

NP

NPN

PClCl

Cl Cl

ClCl

NP

NPN

PClCl

Cl Cl

ClClH

NP

NPN

PN

ClCl

PClCl

NP

NP

Cl

ClCl

Cl

Cl Cl

Cl Cl

NP

NPN

PClCl

Cl Cl

ClClH

NP

NPN

PClCl

Cl Cl

ClCl

101

pair on another [PCl2N]3 attacks the phosphorus cation and the ring of attacked trimer

opens up to give another phosphozenium cation and chain propagation starts.

Termination of the polymerization occurs when the unreacted [PCl2N]3 molecules are

over or by abstracting a chloride ion. Initiation can be done by thermal activation alone or

adding a Lewis acid such as BCl3 or AlCl3 into the system to act as a chloride ion

abstractor.115,116

Scheme 3-4. Mechanism of ROP of [PCl2N]3 by Allcock53,111,114

In the uncatalyzed ROP of [PCl2N]3, the yield is around 40% before the

crosslinking reactions take place.117 Therefore, the uncatalyzed ROP usually produces

insoluble polymer at high conversion. One of the approaches to improve the yield by the

thermal ROP is to employ catalysts to lower the reaction temperature. Catalysis by Lewis

acids like BCl3 and AlCl3 resulted in reduction of the polymerization temperature.39,117

NP

NPN

PClCl

Cl Cl

ClCl

NP

NPN

PClCl

Cl Cl

ClCl

NP

NPN

PClCl

Cl Cl

ClCl

NP

NPN

PN

ClCl

PClCl

NP

NP

Cl

ClCl

Cl

Cl Cl

Cl Cl

102

Sohn and co-workers explain the use of AlCl3 in the polymerization reaction which

decreases the temperature and the time of the reaction with increasing catalyst loading.

However, this method results in low molecular weight polymers (104 – 105). In 2008,

Manners and co-workers describe the use of trialkylsilylium carboranes,

R3Si(CHB11X11), as catalysts to lower the temperature of polymerization. One of the best

examples is Et3Si(CHB11H5Br6) which lowers the polymerization temperature to ambient

temperature.115,117,118 Another very important improvement is the increasing stability time

of [PCl2N]n in solution. It was reported that [PCl2N]n undergoes crosslinking in solvents

like THF, benzene, toluene and chlorobenzene, but in pure diglyme or in 75/25 (v/v) of

diglyme/THF, [PCl2N]n remains uncross-linked for more than four years in air.119

As the phosphazene research area broadened, researchers were also interested in

finding alternative methods for the polymer synthesis, to overcome drawbacks of the

ROP. As a result, alternative methods based on condensation polymerization began to

evolve and they opened the path to control the polymer molecular weight and molecular

weight distribution, giving rise to polymers with narrow polydispersities.48,120

The earliest method was the condensation of PCl5 or PCl3 with ammonia or

ammonium chloride discovered by Chris Allen and co-workers in the 1970’s. The

polymers made by this method were found to have very broad polydispersities with a

lower molecular weight compared to the ROP. Later De Jaeger made medium molecular

weight phosphazene polymers by the condensation of phosphoranimine, Cl3P=NP(O)Cl2.

This undergoes polymerization at 240 °C to 290 °C at atmospheric pressure with the

elimination of P(O)Cl3. Although it gives rise to higher molecular weight polymers

compared to earlier condensations, the polydispersity was found to be still broad.48 In

103

1995, while searching for a better alternative condensation type method to high polymers,

Allcock, Manners, and co-workers reported the first Lewis acid initiated living cationic

condensation polymerization in 1990’s.43

The proposed mechanism of the condensation polymerization of the

phosphoranimine, Cl3P=NSiMe3 which is the monomeric unit to [PCl2N]n in the presence

of trace amounts of PCl5 as an initiator is shown Scheme 3-5. The reaction can be done at

room temperature, and a narrow polydispersity can be achieved by controlling the

monomer to initiator ratio.121 In condensation polymerization, monomer was previously

synthesized directly from PCl5,116,122 which resulted in forming a polymerization inhibitor

chloroamine, ClN(SiMe3)2, and later PCl3 was found as a substitute.116,122

Scheme 3-5. Mechanism of polycondensation43

The initiation of the condensation of Cl3P=NSiMe3 involves two steps. First the

monomer reacts with two equivalents of PCl5 to obtain the ionic species as in step 1 in

Scheme 3-5, which then reacts with an additional equivalent of monomer to form the

short chain cationic species (step 2). By adding additional equivalent of monomer to the

Cl3P=NSiMe3 Cl3P=N-PCl3+ PCl6

-

Cl3P=N-PCl3+ PCl6

- [Cl3P=NPCl2=N-PCl3]+ PCl6-

[Cl3P=NPCl2=N-PCl3]+ PCl6-

+ n Cl3P=NSiMe3

2 PCl5

-Me3SiCl

- n Me3SiCl

- n Me3SiCl[Cl3P=(NPCl2)n=N-PCl3]+ PCl6

-+ n Cl3P=NSiMe3

104

cationic species as shown in step 3, oligomeric products can be obtained.43 In this type of

reaction, the molecular weight of the polymer increases continuously until the supply of

monomer in the system is depleted. Because this is a living polymerization, no chain

termination is involved.48 Although this reaction can be carried out in the bulk under

solvent free conditions or in solution, molecular weight control was compromised due to

the heterogeneous nature of the process. The molecular weight was controlled with

solution polymerization of Cl3P=NSiMe3. After investigating different types of

polymerization solvents, it was found that a high yield of polymer can be obtained in

dichloromethane within a short period of time. The effect of monomer to initiator ratio on

the molecular weight of the polymers has also been studied.121-123

It has also been reported that the time and temperature prior to the addition of

PCl5 affects the molecular weight and molecular weight distribution of the polymer as

shown in Table 3-1. As the time increases before adding PCl5, high molecular weight

polymers are obtained with broader polydispersities. In run 1, the resultant Cl3P=NSiMe3

mixture was stirred at RT overnight without adding any PCl5. The lowest PDI resulted in

run 2 when Cl3P=NSiMe3 was kept at 0 °C for 1 hour before addition of PCl5. According

to the same reference,122 [PCl2N]n can be synthesized completely after adding PCl5 and

stirring overnight at room temperature. The molecular weights were obtained of the air-

stable trifluoroethoxy derivative rather than of [PCl2N]n.

105

a Stirred at 0 °C. Table 3-1. Molecular weights and its distribution of [P(OCH2CF3)2N]n from the one-pot in situ polycondensation.122

The chloropolymer is often contaminated with cyclics, [PCl2N]3 to higher rings or

cyclic oligomers, and they can be removed by vacuum sublimation or distillation at

moderate temperature at 50 to 60 °C and 0.01 to 0.05 mm Hg pressure. The method

described as best for this purpose is the precipitation of a solution of the reaction mixture

in cyclohexane into heptane. Because all the rings, oligomers and chloropolymer have

complete solubility in solvents like benzene, toluene, cyclohexane, tetrahydrofuran, and

chloroform at room temperature, any of those solvents can be used in this regard.111

The chlorophosphazene polymer, [PCl2N]n is considered to be very sensitive to

both air and moisture, which makes it necessary to do the synthesis including bench top

workups, storage and substitutions in an air-free, dry environment to avoid degradation,

branching and cross-linking. Other than that, synthesis has become an ongoing issue due

to its cost, non-reproducibility and poor yields. Over the years, different research groups

have been trying to improve these syntheses in order to overcome above drawbacks.48

Reported here is the detailed synthesis of [PCl2N]n by both one-pot in situ

polycondensation of Cl3P=N(SiMe3)2 and ring opening polymerization of [PCl2N]3. Both

methods reported are slightly different from the synthetic routes given in the literature.

Run Time (before adding PCl5) PCl3 (mmol) LiN(SiMe3)2 (mmol) PCl5 (mmol) Mw PDI103,300 2.35

59,600 1.262 1 ha 10.3 10.3 0.51 49,600 1.243 1 h 8.2 8.2 0.17 20,900 1.614 6 h 8.3 8.3 0.41 124,000 2.145 2 days 80.2 81.3 3.98 245,100 3.95

1 0 h 218 220 0

106

The condensation polymerization was done according to a procedure reported by Bin

Wang122 whereas ROP was done according to the procedure described by Allcock.111 The

characterization of the two [PCl2N]n was done by 31P NMR and MS. Further, their

molecular weights were also determined by GPC of the derivative [P(OC6H5)2N]n.

Thermal studies of [P(OC6H5)2N]n were also carried out.


3.2.1 One-pot in situ polycondensation

The first approach carried out in our lab for the synthesis of [PCl2N]n was the

living cationic condensation as a one-pot in situ synthesis (Scheme 3-6). 48,120,122 In order

to obtain the pure polymer, the synthesis was slightly modified from the procedure

reported by Bin Wang.122 The first step involves the synthesis of chlorophosphine, Cl2P-

N(SiMe3)2 starting with PCl3 and LiN(SiMe3)2. This intermediate chlorophosphine is

converted to the monomer phosphoranimine, Cl3P=N(SiMe3)2 by reacting with SO2Cl2.

Being a source of chlorine gas, it oxidizes Cl2P-N(SiMe3)2 into the

Cl3P=N(SiMe3)2.116,122 This route to the polymer precursor has been described as an

improved and high yield one.116,121,123-125

107

III-1a

Scheme 3-6. Overall synthesis of compound III-1a

The initial characterization of the [PCl2N]n - III-1a was done by 31P NMR

spectroscopy. The first reaction was carried out with 10 times scale up but otherwise

identical procedure as reported in the literature,122 which involved stirring the reaction

mixture at room temperature overnight. The resultant polymer showed a sharp resonance

at -17.7 ppm in 31P NMR spectrum. It also showed another two significantly intense

peaks corresponding to [PCl2N]3 at 20.9 ppm and an intermediate species at 15.9 ppm

(Figure 3-2a), indicating the incompleteness of polymerization. As an adaption to the

procedure, the reaction mixture was then heated at 100 -110 °C for a day to accelerate

polycondensation. Figure 3-2b shows 31P NMR spectrum observed after heating, and it

clearly shows the disappearance of the intermediate species at 15.9 ppm. Interestingly,

PCl3 + LiN(SiMe3)2

Cl2P-N(SiMe3)2

Toluene 0 °C

- LiCl

SO2Cl2 0 °C

- Me3SiCl - SO2

Trace PCl5

- Me3SiCl

Cl3P=NSiMe

3

[PNCl2]

n

108

after the heat treatment, the resonance for [PCl2N]3 has decreased in intensity. As can be

seen in Figure 3-2b, the singlet for [PCl2N]n sharpens, suggesting its low polydispersity,

which is in agreement with the calculated PDI values for [PCl2N]n from condensation,

which will be discussed later in the chapter.

The next step involved the purification in order to get rid of the [PCl2N]3.

Purification has become very important in polyphosphazene chemistry in order to obtain

the pure polymer, which in turn has a great effect on the properties of

poly(organophosphazenes). In our lab, purification was achieved basically by two

different methods. The first method involved was the stirring of the polymer mixture in a

1:1 mixture of dry hexane: dry heptane at a higher temperature (~80 °C) for about 3

hours. Because all the rings have solubility in hexane and heptane,111 pure polymer was

obtained by decanting the solvent mixture. Although pure polymer was obtained by this

route, it could lead to crosslinking and thereby lowering polymer yield due to heating at a

higher temperature for a long time.

The next method involves dissolving the polymer mixture in a minimum amount

of dry THF (10 mL) because both rings and polymer dissolve in it as discussed earlier.

The solution was transferred by cannula into a Schlenk flask that contained vigorously

stirring dry hexane. As the THF solution drops into hexane, an oily precipitate forms on

the bottom of the flask. Once the transfer was done, the precipitate was separated by

decanting the solvent and redissolved in dry THF. Upon the removal of the volatile

components under vacuum, a single peak was observed in the 31P NMR spectrum. Figure

3-2c depicts the 31P NMR spectrum of the polymer after the purification.

109

Chemical shift (ppm)

Figure 3-2. 31

P NMR spectra showing the compound III-1a in CDCl3 (a) sampling after

stirring at RT for overnight, (b) after heating at 110 °C for a day, (c) hexane purified

polymer.

(a)

(b)

(c)

110

Among the series of reactions carried out using the above one pot in-situ

condensation of Cl3P=N(SiMe3)2 (Scheme 3-6), only 13 out of a total of 25 reactions

ended up giving pure polymer ranging from 6 – 46% in yield. The yield of polymer was

very low when PCl3 was added quickly into the reaction mixture. Therefore, another

variation added to the synthesis was by diluting PCl3 and SO2Cl2 with dry toluene and

adding them over a period of about an hour instead of a short time using the cannula

transfer. All the other times, pure polymer was not isolated and an insoluble, rubbery

material, believed to be cross-linked polymer, was isolated instead. The insoluble

polymer becomes swollen when exposed to organic solvents. Therefore, these results

clearly demonstrate the irreproducibility and inconsistency of the polymerization

reaction.

3.2.2 Ring Opening Polymerization – A Preliminary Study

As a preliminary study, ROP of [PCl2N]3 was carried out for the synthesis of

[PCl2N]n as our second approach. As mentioned earlier, this was done according to the

literature procedure reported by Allcock111 with some alterations. Although the

polymerization strictly depends on the purity of the monomer [PCl2N]339 to ensure the

absence of an unidentified polymerization inhibitor, the [PCl2N]3 purchased from the

Aldrich was used for this purpose without any sublimation. According to the integration

of the 31P NMR spectrum, [PCl2N]3 contains 16.6% of [PCl2N]4. Because the ROP of

[PCl2N]3 is not inhibited by [PCl2N]4, in fact both undergo the ROP, purification of

[PCl2N]3 was deemed unnecessary. During the high-temperature ROP, it is necessary to

constantly observe the sealed tube inside the oil bath until the time of viscosity increases

111

because the polymerization time is different from one sample to another. According to

Allcock, reaction needs to be terminated when 70% to 75% of the trimer has been

polymerized in order to obtain soluble polymer. Beyond this point, the polymer

undergoes cross-linking rapidly and unpredictably.111

Once the polymerization was over, the tube was broken by percussion inside the

glove bag, and the 31P NMR spectrum of an aliquot was run in CDCl3, which is depicted

in Figure 3-3(a). There is an intense peak for [PCl2N]3 at 20.6 ppm along with a smaller

amount of polymer at -17.6 ppm. There is also a shoulder peak at -17.7 ppm, which is

shown in Figure 3-4 and could be a result of different end groups. In between those two

peaks, the single peak at -5.9 ppm represents the tetramer, [PCl2N]4.40 There are two

peaks at -14.8 ppm, -14.9 ppm and another short single peak at -16.9 ppm. Assignment of

these peaks is inconsistent in the literature.40,126

112

Chemical Shift (ppm)

Figure 3-3. 31

P NMR spectra of compound III-1b in CDCl3 (a) sampling after breaking

the tube (b) after vacuum sublimation (c) purification into hexane, (d) polymer

completely purified by hexane.

(d)

(b)

(c)

(a)[PCl2N]3

[PCl2N]n

113


Figure 3-4. Expanded 31

P NMR spectrum shown in Figure 3-3(a).

Dry chloroform was used to separate the insoluble polymer from the soluble

[PCl2N]n and the small rings. Once they dissolved in chloroform, the solution became

highly viscous, making it difficult to remove the insoluble polymer from the solution.

One of the best techniques to remove the insoluble polymer was to filter through oven-

dried glass wool in which the swelled insoluble polymer was held. Figure 3-3b shows the

peaks corresponding to the product obtained after the first sublimation after removing the

insoluble polymer. First the solvent, CHCl3 was pulled off on the Schlenk line at room

temperature overnight. Then vacuum sublimation was done at 70 °C first and then at 75

°C for about four days to remove the more volatile rings, primarily [PCl2N]3 and

[PCl2N]4. However, some crystals had deposited on the side of the sublimation apparatus

after crystals moved along the condenser. Once the apparatus was taken into the glove

box, some crystals of [PCl2N]3 and [PCl2N]4 were also removed manually from the round

- 14.8

-16.9

Shoulder peak

-17.7

[PCl2N]n

-17.6

- 14.9

[PCl2N]m m ≥ 5

(a)

114

bottom flask. Figure 3-3b is the spectrum taken after the sublimation where [PCl2N]3 and

[PCl2N]4 crystals were removed. This spectrum is similar to the spectrum shown at Figure

3-3a, but the intensity of [PCl2N]n peak is now higher than that of the [PCl2N]3 peak. The

next step was cleaning the product with dry hexane, in which all the cyclic rings dissolve.

In spectrum c, the rings are seen less intense after the first washing with dry hexane.

After several washings, all the rings were removed leaving only the polymer peak which

shows up at -17.6 ppm in Figure 3-3d. The shoulder peak is also no longer observed. The

results were not always the same even though the reactions were carried out the same

way. In spite of dissolving the reaction mixture in dry hexane to get rid of small cyclics,

they may still appear in the 31P NMR spectrum.

Therefore, this route to [PCl2N]n was also not reproducible, and several possible

improvements to increase the yield of polymer within a short reaction time would be the

use of pure [PCl2N]3 as a starting material, immediate percussion of the tube after the

polymerization, and increased temperature for vacuum sublimation and fast workups. The

time of termination greatly affects the molecular weight of the polymer. Therefore,

careful control of both temperature and time are necessary. More studies are necessary to

determine the optimum reaction conditions required for increased yields. The overall

process of ROP can be shown as follows (Scheme 3-7).

115

Scheme 3-7. Overall process of ROP (compound III-1b)

In order to obtain the pure polymer from the ROP of [PCl2N]n, it is important to

do many washings with dry hexane or heptane. This results in reduced polymer yields

and is a very time consuming process when compared to the condensation

polymerization. Other than that, it is necessary to constantly observe the polymerization

process to stop the reaction before the viscosity increases. The yield of the polymer from

the ROP, which is relatively a cheap approach due to the use of less expensive of

chemicals, was relatively low (~9%). The final polymer from the ROP is as a colorless

gel whereas a dark brown colored polymer is the result of condensation route. The failure

to terminate heating before the viscosity increases results in the formation of insoluble

polymer which is clearly observable as a transparent rubbery elastomer.

Although the 31P NMR is the primary characterization method in identifying the

polymer, it is necessary to run mass spectrometry to see the repeating unit of the polymer.

Figure 3-5 shows the ESI mass spectrum of the [PCl2N]n purchased from Aldrich.

Although the synthetic procedure was not known, [PCl2N]n had a good distribution, and

furthermore, longer polymer chains were detected. Therefore this can be used as a

NP

NPN

PClCl

Cl Cl

ClCl

[PCl2N]n + Rings + Insoluble polymer

[PCl2N]n + Rings

[PCl2N]n

250 °C

Δ

116

reference for the ESI-MS of the polymers synthesized in the lab. The ESI-Q/ToF mass

spectrometer was operated in the negative mode in order to detect negative ions

generated during the ionization process. The sample for the MS analysis was completely

dissolved in dry CHCl3. The resulting ESI mass spectrum of the polymer, III-1a is shown

in Figure 3-6. The major peaks occur at the expected intervals of 115 Da which exactly

match the molecular weight of the monomeric unit [PCl2N]. Although the repeating

pattern can be clearly seen with 115 Da per monomeric unit, the Aldrich polymer exhibits

a better distribution along with higher molecular weight compared to our polymer.

Figure 3-5. ESI mass spectrum of [PCl2N]n purchased from Aldrich.

1000 1500 2000 2500 3000 3500 4000

1850 1900 1950 2000 2050 2100 2150 2200 m/z

115115

115

1869.1 1984.5 2099.3 2214.0

m/z

117

Figure 3-6. ESI-Q/ToF mass spectrum of compound III-1a.

Figure 3-7. Inset of the ESI-Q/ToF mass spectrum of compound III-1a from 800-1120

m/z.

An inset of the ESI-Q/ToF mass spectrum of compound III-1a from 800-1120

m/z is shown in Figure 3-7. It demonstrates three different distributions due to different

end groups. But it was also found that the mass of the end group of the main polymer

115

115

115

115

115

115

118

distribution was zero suggesting the polymer has a ring structure or the tadpole structure,

which is a linear chain with a cyclic in one end as shown in the Figure 3-8.

Figure 3-8. Suggested tadpole structure of the [PCl2N]n.

Because chlorine has two stable isotopic forms (35

Cl and 37

Cl), the isotopic distribution of

[PCl2N]n (III-1a) was also obtained (Figure 3-9) and it exactly matched the theoretical

isotopic distribution.

Figure 3-9. Isotopic distribution of compound III-1a

3.2.3. Molecular Weight Determination

In order to determine the molecular weight of [PCl2N]n synthesized from both

methods, poly[bis(phenoxy)phosphazene], P(OC6H5)2N]n was synthesized separately as

shown in Scheme 3-8. The air and moisture sensitive pure [PCl2N]n cannot be used for

N

PN

P

NP

Cl

Cl

ClCl

N P N P

Cl

Cl

Cl

Cl

Cl

Cln

m/z896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918

%

0

100906.33

904.34

902.33

900.38

905.35

908.35

907.36

910.33

909.33

912.33

911.34

914.35

916.33

119

GPC analysis due to its high reactivity. But once substituted, it becomes stable and

unreactive. The substitutions were done with both compounds, III-1a and III-1b

separately. The characterization of the P(OC6H5)2N]n polymers was done by both 31P

NMR and MALDI before running GPC. Figure 3-10 depicts the single peak at -19.3 ppm

in 31P NMR spectrum for compound III-2a. Compared to [PCl2N]n, the peak of

P(OC6H5)2N]n shifts down-field. For the compound III-2b, the peak was observed at -

19.2 ppm in the 31P NMR spectrum, whereas in the 1H NMR spectrum it was seen at 6.97

ppm as shown in Figure 3-11.

Scheme 3-8. Synthesis of P(OC6H5)2N]n (compound III-2). This was done for both III-1a and III-1b, separately, and yielded polymers III-2a and III-2b.

P NO

On

OH

2.[PCl2N]n, reflux

1. KH, THF, RT

120

31P Chemical Shift (ppm)

Figure 3-10. (a) 31

P NMR of compound III-1a (-17.8 ppm) and (b) 31

P NMR of

compound III-2a (-19.3 ppm) in CDCl3.

Figure 3-11. 1H NMR (top left) and

31P NMR (bottom right) spectra of compound

III-2b in CDCl3.

(b)

(a)

tu

3

T

un

d

th

m

to

as

1

F

Figure

urn confirms

253, 3484, 3

The peaks oc

nit of the po

istribution a

he same inter

major series.

Althou

o the fast deg

s depicted in

849, 2080 an

igure 3-12. M

e 3-12 show

s the mass of

3715, 3946, 4

curred at the

olymer. This

t 2945, 3176

rvals of 231

ugh the mas

gradation, th

n Figure 3-13

nd 2311 m/z

MALDI-ToF

s the MALD

f this polyme

4177, 4408,

e expected in

is not the on

6, 3407, 363

Da. This ser

s spectrum f

he MALDI-T

3. It also sho

z which occu

121

F spectrum o

DI-ToF spect

er. The mass

4639 corres

nterval of 23

nly series ob

8, 3869, 410

ries results f

for the comp

ToF spectrum

ows the majo

ur at expecte

of compound

trum of the c

s spectrum h

sponding to

31 Da, which

bserved in th

00, 4331, 45

from the loss

pound III-1b

m was obtain

or peaks at 6

ed intervals o

d III-2a.

compound II

has major pe

12-21 mers,

h represents

he spectrum.

62, 4793 and

s of –C6H5 (

b could not b

ned for the c

694, 925, 115

of 231 Da. T

II-2a which

aks at m/z 3

respectively

the monome

There is ano

d 5023 m/z w

77 Da) from

be obtained d

compound II

56, 1387, 16

There are ano

in

021,

y.

eric

other

with

m the

due

II-2b

618,

other

tw

in

w

[P

th

w

li

wo different

n Figure 3-12

Table

were obtained

P(OC6H5)2N

hen the weig

were calculat

iterature. Ac

minor distri

2, this has be

Figure 3-1

3-2 summar

d of THF sol

N]n, and polyd

ght average m

ed. Interestin

cording to th

ibutions that

een observed

3. MALDI-T

rizes the GP

lutions. The

dispersity in

molecular we

ngly, the res

he literature,

122

can be obse

d to be low i

ToF spectru

PC data of all

number ave

ndex (PDI) w

eight (Mw) a

sults are cont

, molecular w

erved. Comp

in molecular

um of compo

l the chlorop

erage molecu

were directly

and number o

tradicting w

weight distri

pared to the s

r weight.

ound III-2b.

polymers syn

ular weight (

y obtained fro

of repeat uni

with the value

ibution value

spectrum sho

nthesized wh

(Mn) of the

om GPC, an

its of [PCl2N

es reported in

es of [PCl2N

own

hich

nd

N]n

n the

N]n

123

from ROP are supposed to be broader giving higher PDI values. But all the values are

really low with very sharp phosphorus NMR peaks.

a [P(OC6H5)2N]n b[PCl2N]n Table 3-2. Weight average molecular weights (Mw) and polydispersity indices (PDI), and repeat units of [PCl2N]n obtained from GPC. 3.2.4. Thermal Analysis of Phenoxy Polyphosphazenes

Glass transition temperature (Tg) has become an excellent tool in determining the

flexibility of polymers, which helps predict their properties. As mentioned, it is a measure

of the flexibility, and below Tg, polymer becomes a glass and the backbone bonds tend to

have insufficient thermal energy to undergo significant thermal motions. As the

temperature reaches above its Tg, it allows torsional motions, becoming rubbery or

elastomeric. In mid 1960s, Allcock and co-workers reported the Tg of [PCl2N]n

synthesized by ROP route as -66 °C proving its inherent skeletal flexibility.60 At the same

time, they came up with values for lots of substituted polymers that had synthesized up to

that date.

Although we have not performed thermal studies of chloropolymer, an attempt was

made at determining the thermal properties of [P(OC6H5)2N]n. Thermograms of

[P(OC6H5)2N]n synthesized by Scheme 3-8 are shown in Figure 3-14. Both the two

[PCl2N]n Mn(Da)a PDIa Mw (Da)b Repeat units (n)b

III-1a 2.3 × 105 1.9 1.1 × 105 995

4.4 × 105 1.6 2.2 × 105 1900

III-1b 6.4 × 104 1.2 3.2 × 104 277

4.9 × 104 1.2 2.5 × 104 212

124

compounds show several steps of weight losses. Degradation temperatures and associated

parameters obtained from these thermograms are summarized in Table 3-3. D0.05, the

initial decomposition temperature (IDT) at which 5% decomposition occurs is about 50

°C higher for the compound III-2a compared to III-2b. The temperature at which 50% of

decomposition occurs (D1/2) follows the same trend. The maximum rate of decomposition

temperature, MRD was found to be 14 %/min at 376 °C for compound III-2a whereas it

was 6 %/min at 355 °C for compound III-2b.105

The Tg value for the [P(OC6H5)2N]n has been reported as -8 °C in literature60

suggesting it has a microcrystallinity due to the increased Tg compared to its precursor,

[PCl2N]n. Although polymer backbone is flexible itself, the introduction of –OC6H5

groups introduce steric interference due to the bulkiness and rigidity of the phenol ring.

Therefore, bulky and rigid substituents introduce restrictions to the flexibility of polymer.

Table 3-3. Inert atmosphere (N2) TGA parameters of [P(OC6H5)2N]n.

D 0.05 D 1/2 MRDTCompound III-2a 293 376 376 9.4Compound III-2b 244 378 355 19

Inert atmosphere (°C)Compound Residue analysis (%)

F

p

op

[P

T

m

w

in

w

igure 3-14. I

In thi

olycondensa

pening polym

PCl2N]n in te

The synthesiz

molecular we

were determin

nconsistent w

were perform

Inert atmosp

is chapter, sy

ation by sligh

merization w

erms of repro

zed polymer

eights and m

ned by GPC

with the liter

med by TGA.

phere (N2) th

ynthesis of [P

htly adapting

was also atte

oducibility a

s were initia

molecular wei

C by synthesi

rature. Moreo

.

125

hermograms

3.3 Conclus

PCl2N]n has

g the literatu

empted only

and yield of p

ally character

ight distribut

izing [P(OC6

over, therma

of compoun

sion

been report

ure procedur

as a prelimin

polymerizat

rized by NM

utions of thos

6H5)2N]n. Th

al studies of

nds III-2a an

ted mainly b

re. Furthermo

nary study. T

tion has been

MR and MS.

se polymers

he results ob

f the substitut

nd III-2b.

y one-pot in

ore, a ring

The synthes

n a challenge

Further,

synthesized

tained were

ted polymer

n situ

is of

e.

d

rs

126

3.4 Experimental


Standard Schlenk techniques were used with all manipulations in dealing with

potassium hydride (KH) and all reactions were carried out under a nitrogen atmosphere.

The same standard Schlenk techniques were also used for the synthesis of [PCl2N]n. The

compound (PCl2N)3, purchased from Aldrich, was stored in an inert-atmosphere

glovebox. Lithium bis(trimethylsilyl)amide, LiN(SiMe3)2 and phosphorus (V) chloride,

PCl5 were purchased from Alfa Aesar and stored in the air free glove box. Phosphorus

(III) chloride, PCl3 (98% min) and sulfuryl chloride, SO2Cl2 (97%) which is a source of

chlorine gas were also purchased from Alfa Aesar. They were stored in Schlenk

flasks under an inert atmosphere and used as received. All the glassware was rinsed

thoroughly and oven dried at 100 °C prior to the synthesis. Phenol was purchased from

Aldrich and polyphenylmethylsiloxane was purchased from Gelest. The Schlenk and

vacuum lines had a maximum vacuum of ~ 10-3 mm and 2 ×10-4 mm, respectively.

Potassium hydride in mineral oil purchased from Aldrich was filtered and washed with

dry THF and stored in the glovebox. THF, toluene, hexane and chloroform were dried

and deoxygenated by a Pure SolvTM system. All other reagents were used without any

further purification. NMR spectra were recorded on a Varian Mercury 300 MHz

instrument using deuterated DMSO and CDCl3 as NMR solvents. The 1H NMR

resonances were referenced relative to the deuterated solvent. The 31P NMR spectra were

referenced with external H3PO4 at δ 0 ppm. Mass spectrometric analysis using

electrospray ionization (ESI) was performed by both Bruker Esquire-LC quadrupole ion-

trap (QIT) mass spectrometer and Waters Synapt HDMSTM quadrupole Time-of Flight

127

(Q/ToF) mass spectrometer. Matrix Assisted Laser Desorption/Ionization Time-of-Flight

(MALDI-ToF) mass spectra were acquired on a Bruker Reflex III MALDI-ToF mass

spectrometer. Compound III-2a was run under a negative mode using a matrix (α-cyano-

4-hydroxycinnamic acid: CHCA) in acetonitrile (70%) and water (30%) while positive

mode was used to run III-2b with the same sample preparation technique. Solution of

[PCl2N]n in dry CHCl3 were examined under negative mode. Mass spectrometric analysis

was performed by the mass spectrometry facility in the Department of Chemistry at the

University of Akron by Alyison Leigh, Vincenzo Scionti and Bryan Katzenmeyer.

Thermo Gravimetric Analysis was done by a QSeries – [Q500 – 0882 – TGA

Q500@Mfg – tga] TGA instrument at a scanning rate of 10 °C/min under N2 atmosphere

in the Department of Polymer Science and Polymer Engineering at The University of

Akron. Gel Permeation Chromatography (GPC), was run by Jon Page in the Department

of Polymer Science and Polymer Engineering. The molecular weights of the phenoxy

polymers were determined by means of a Hewlett-Packard HP1090 gel permeation

chromatograph equipped with a refractive index detector. The sample was eluted with a

0.1% by weight solution in THF through PLgel columns. Narrow molecular weight

distribution polystyrene was used as a standard for calibrations.

3.4.2. Synthesis of poly(dichlorophosphazene) via one-pot in situ polycondensation (III-1a) LiN(SiMe3)2 (30.0 g, 179 mmol) was weighed into a 500 mL Schlenk flask inside

the dry box. The solid was dissolved in about 150 mL of dry toluene and it was immersed

in an ice bath at 0 °C with the N2 purge. PCl3 (15.6 mL, 179 mmol) was diluted with 30

mL of dry toluene in a Schlenk flask and it was added dropwise into the Schlenk flask

128

containing LiN(SiMe3)2 at 0 °C by cannula over a period of 1 hour. The reaction mixture

was left at 0 °C for another half an hour under N2 purge. The ice bath was removed and

the mixture was stirred with no N2 purge for one more hour at room temperature. The

reaction mixture was brought back to 0 °C and SO2Cl2 (14.8 mL, 183 mmol), which was

diluted with 30 mL of dry toluene was added dropwise over an hour by cannula. The

reaction was stirred for an hour as the mixture reached room temperature. PCl5 (1.85 g,

8.95 mmol) was added to the mixture and it was stirred at room temperature overnight.

The temperature was raised to 100-110 °C for a day. After cooling to room temperature

the solid was removed using Celite®, the volatile components were removed in vacuo and

a dark brown viscous liquid was obtained. The liquid was redissolved in 10 mL of dry

THF and transferred to another Schlenk flask containing dry hexane. Because the

insoluble polymer stuck to the bottom of the flask, hexane was decanted and polymer was

redissolved in 10 mL of dry THF. The volatile components was removed under vacuum.

Yield: 7.70 g, 66.4 mmol, 37 %.

3.4.3. Synthesis of poly(dichlorophosphazene) via ring opening polymerization (III-1b)

[PCl2N]3 purchased from Aldrich was crushed into a fine powder and weighed into

the oven baked glass tube (110 °C for an hour) inside the glove box (16.7 g, 48.1 mmol).

The tube was flame sealed under vacuum on the high vacuum line. It was wrapped with a

copper wire and connected to an anti-clockwise rotating motor, which kept the tube in a

pre-heated silicone oil bath as it rocked back and forth. The temperature of the oil bath

was maintained at 250 °C for about 5 hours and 30 min until the liquid in the tube

became viscous. The tube was taken out of the oil bath and cooled overnight. The tube

129

was taken into the polyethylene glove bag, it was broken by percussion, and dry CHCl3

(20 mL) was added to dissolve all the rings, oligomers and polymers. The solution was

filtered in to a sublimation container through a funnel stuffed with oven baked glass

wool, in which the insoluble polymer is held. The glass wool was washed well with

additional CHCl3 to remove any soluble polymer and the washings were combined with

the other CHCl3 solution. The sublimation apparatus consisted of a round bottom flask

which contained the CHCl3 solutions and a long condenser. Under vacuum the volatile

components were removed on the Schlenk line overnight. Still under vacuum

sublimation, the temperature was maintained around 70 to 75 °C to remove all the small

rings. The sublimation was continued for 4 days on the Schlenk line and the apparatus

was taken into the glove box. The sublimate was separated from the polymer and dry

hexane was added to polymer to extract any rings left. This was done until no more rings

appear in 31P NMR spectrum of the polymer. The volatile components were removed

under vacuum. Yield: 0.52 g, 4.48 mmol, 9 %.

3.4.4. Synthesis of poly[bis(diphenoxy)phosphazene] using compound III-1a (III-2a)

Potassium hydride (0.43 g, 10.8 mmol) was weighed inside the dry box into a

Schlenk flask and about 10 mL of dry THF was added. Phenol (1.01 g, 10.8 mmol)

dissolved in about 20 mL of dry THF was added using a pipette under N2 purge.

Compound III-1a (0.50 g, 4.31 mmol) dissolved in 40 mL of dry THF was added. The

resultant clear yellowish reaction mixture was refluxed at 80 °C for 5 and ½ days. The

reaction mixture was cooled and the precipitate was removed by filtration. The solvent

was removed from the filtrate under vacuum to obtain a solid which was rinsed with

130

water to remove any salts present. The solid was dried in air to give a powder. Yield: 0.26

g, 1.12 mmol, 26 %. 31P {1H} NMR (CDCl3- d6): δ -19.3 ppm (s). 1H NMR (300 MHz,

CDCl3): δ 6.82 ppm (s).

3.4.5. Synthesis of poly[bis(diphenoxy)phosphazene] using compound III-1b (III-2b)

Potassium hydride (0.26 g, 6.41 mmol) was weighed inside the dry box into a

Schlenk flask and about 20 mL of dry THF was added. Phenol (0.58 g, 6.17 mmol) was

crushed into a fine powder and baked at 100 °C for 3 hours. It was dissolved in about 15

mL of dry THF and added into the stirred KH suspension using a pipette under N2 purge.

Compound III-1b (0.29 g, 2.47 mmol) dissolved in 5 mL of dry THF was added and the

resultant clear light brown colored mixture was refluxed at 80 °C for 7 days. The reaction

mixture was cooled and filtered using Celite® and the precipitate was isolated from the

filtrate. The volatile components were removed from the filtrate under vacuum to obtain a

light brown colored sticky solid. The solid was stirred at room temperature with water to

remove any salts present and a light brown powder was isolated. The powder was dried in

air. Yield: 0.11 g, 0.47 mmol, 19 %. 31P {1H} NMR (CDCl3- d6): δ -19.2 ppm (s). 1H

NMR (300 MHz, CDCl3): δ 6.79 ppm (s).

131

CHAPTER IV

SYNTHESIS AND CHARACTERIZATION OF

POLY(AZOLYLMETHYLPHENOXY) AND POLY(PYRIDINOXY)

PHOSPHAZENES AS CANDIDATES FOR PEMS

4.1 Introduction

Polyphosphazenes comprise by far the largest class of inorganic backbone

polymers among all the inorganic polymers known.1 Since the first synthesis of [PCl2N]n,

more than 250 different nucleophilic reagents such as alkoxides, aryloxides, primary and

secondary alkyl and aryl amines and organometallic reagents have been used in

substitution reactions,37 giving rise to at least 700 different polymers38 via primary

substitution or by secondary reactions that modify the substituents introduced by the

primary substitution. Poly(organophosphazenes) possess numerous properties that are

attractive for a wide range of applications. This is achieved by replacing the halogens on

the phosphazene backbone by different substituents. This ease in tailoring properties was

a major breakthrough in inorganic backbone polymers.37,38

Scheme 4-1. Synthesis of [PR2N]n

P NCl

Cln

Macromolecular Substitution

P NR

Rn

ROPNP

NPN

PClCl

Cl Cl

ClCl

132

The simplest situation is where polymers have one type of substituent along the

chain. Additionally, mixed substituent polymers can also be synthesized with two or

more different reagents.127-129 The synthesis of polymers depends mainly on the

avoidance of unwanted side reactions to avoid complications during the substitution. The

first polymer to be made was [PN(OCH2CF3)2]n which was found to be a hydrophobic

film-forming material. [PN(OC6H5)2]n was another well studied polymer synthesized

during the same time.41

Although the major route towards the poly(organophosphazenes) is by

macromolecular substitution, a few cyclotriphosphazenes bearing organic side groups

have been found to undergo thermal ring opening polymerization.102,130,131 This is an

attractive synthetic method due to the ease of isolation and purification of the

cyclotriphosphazene compared to the high molecular weight polymers. Only a handful of

cyclic trimers fully substituted with transannular metallocenyl unit or transannular bridge

inducing ring strain have been found to undergo this kind of ROP.130

Sohn and co-workers describe the direct melt polymerization of

hexakispyridinoxycyclotriphosphazenes in to their corresponding linear polymers.102

According to their experimental details, hexakis(2-pyridinoxy)cyclotriphophazene

(compound II-7) and hexakis(4-pyridinoxy)cyclotriphophazene (compound II-9) were

found to undergo ring opening upon heating at temperatures ~ 150 and 200 °C,

respectively but not the hexakis(3-pyridinoxy)cyclotriphophazene (compound II-8). In

the ROP synthesis, ~0.5 g of pyridinoxy trimer was placed in a Pyrex tube, it was

subjected to vacuum at 0.1 mmHg and the tube was sealed. The sealed tube was heated in

an oven rotating at 1 rpm to stir the reactants. After the desired time, the tube was cooled

133

and broken, and the contents were washed with excess amounts of hexanes to obtain the

polymer.

This chapter discusses the synthesis and characterization of several different

poly(azolylmethylphenoxy)phosphazenes and poly(pyridinoxy)phosphazenes as

candidates for PEMs. The syntheses of the polymers was done by the substitution route

or by the ROP of organo-substituted triphosphazenes. The polymers and their precursors

were characterized by NMR and MS methods. For some of the polymers, thermal

properties of were measured by TGA and DSC.


4.2.1 Synthesis and Characterization of Azolylmethylphenoxy Polyphosphazenes

The synthetic pathway to poly{bis[4-(1H-1,2,4-triazol-1-

ylmethyl)phenoxy]phosphazene}(compound IV-1) is summarized in Scheme 4-2. In this

reaction, compound II-2 was reacted with slight excess of KH in THF to obtain the

triazolmethylphenoxide anion with the production of hydrogen gas as a byproduct. With

the introduction of [PCl2N]n to the reaction mixture, two equivalents of the anion undergo

a nucleophilic substitution reaction with one equivalent of polymer repeat unit. The

substituted polymer was collected as a light yellow powder in low yield. The data from

the two successful reactions are listed in Table 4-1. The yield of the polymer seems to

increase with increasing reaction time from 4 days to 6 days.

134

IV-1

Scheme 4-2. Synthesis of compound IV-1

Table 4-1. Synthesis of compound IV-1.

Determining the reaction time required for a complete substitution of the polymer

was one of the major issues in this substitution reaction. A few initial reactions ended up

giving water soluble polymer products. Partial substitution of the Cl atoms of [PCl2N]n

occurs with sterically hindering substituents. If the phosphazene backbone is only

partially substituted the polymer has defects attributable to the chlorines on phosphorus,

which cause the polymer to unzip and become water soluble and degradable. Due to

water solubility, purification of IV-1 became problematic. It was difficult to remove the

P NO

O

N

N NN

NN

n

OH

NN

N

1. KH, THF, RT

2. [PCl2N]n, reflux, 6 d.

II-2

Reaction No. Reaction time Yield (%)Wt (g) equi. mol Wt (g) equi. mol Wt (g) equi. mol

1 2.376 2.4 0.589 2.6 0.655 1 4d 62 13.334 2.4 3.307 2.6 3.675 1 6d 31

Compound II-2 KH PDCP

135

precipitated KCl from IV-1 by extraction or washing. Another cause of partial

substitution is that the polymer precipitates from the solution before complete chlorine

replacement. Therefore, in order to obtain complete substitutions, the reactions were run

for at least four days compared to the synthesis of substituted trimers.

Polymer IV-1 was characterized by 31

P NMR spectroscopy and a resonance was

observed at -18.8 ppm as shown in Figure 4-1. Compared to the [PCl2N]n, the peak is

broader and shifted up-field (Figure 3-2). In the 1H NMR spectrum (Figure 4-2), the

peaks are very broad compared to its hexa substituted trimer (Figure 2-7). The broader

peaks in the substituted polymer are a result of different polymer chains having different

lengths.


Figure 4-1. 31

P NMR spectrum of compound IV-1 in d6-DMSO.

136


Figure 4-2. 1H NMR spectrum of compound IV-1 in d6-DMSO.

Mass spectrometry has been a crucial tool in determining the repeating pattern of

polymers. The MALDI mass spectrum of IV-1 is shown in Figure 4-3. In this spectrum,

the major peaks occur at the expected interval of 393 Da corresponding to 5-17 mers.

137

Figure 4-3. MALDI-ToF spectrum of compound IV-1 showing the repeat unit of PN7C18O2H16.

The synthesis of polymer IV-2, poly{bis[4-(1H-5-methyltetrazol-1-

ylmethyl)phenoxy]phosphazene}is shown in Scheme 4-3. Compound II-3 and KH were

combined in one to one ratio to obtain the corresponding tetrazolmethylphenoxide, which

was reacted with [PCl2N]n. The polymer was isolated as a light brown solid. The 31P

NMR spectrum of IV-2 is shown in Figure 4-4. It shows not only a broad resonance for

the polymer at -19.4 ppm but also two peaks at -14.0 and -14.5 ppm representing

substituted pentamer and hexamer respectively. The two peaks appeared because

[PCl2N]n used in this reaction was not completely pure. The 1H NMR spectrum of IV-2 is

depicted in Figure 4-5 whereas the 13C NMR spectrum is shown in Figure 4-6.

3555

.135

2000 2500 3000 3500 4000 4500 5000 5500 6000 650039

48.1

84

4341

.247

4734

.301

2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

393

m/z

393

393

138

IV-2



Figure 4-4. 31


OH

N

N

NN

1. KH, THF, RT

2. [PNCl2]n, reflux, 4 d.

P N

O

O

N

NN

N

N

N

NN

n

II-3

139




Figure 4-6. 13

C NMR spectrum of compound IV-2 in d6-DMSO.

Figure 4-7 depicts the MALDI-ToF mass spectrum of IV-2 and it also confirms

the mass of the polymer. In this spectrum, the major distribution can be observed at the

expected intervals of 423 Da, which is consistent with the PN9C18O2H18 repeat unit of the

140

polymer. There appear to be three different end groups to IV-2 and only 3-6 mers

obtained.


4.2.2 Synthesis and Characterization of Pyridinoxy Polyphosphazenes

4.2.2.1 Synthesis via Substitution Route

In synthesizing pyridinoxy substituted polyphosphazenes, the same issue of

incomplete substitution was evident.

After several unsuccessful attempts of synthesizing compound IV-3, only one

reaction worked really well giving water insoluble polymer. The synthetic pathway for

compound IV-3 is illustrated in Scheme 4-4. In the synthesis, 3-pyridinol which was

reacted with KH in order to obtain 3-pyridinoxide and then it was reacted with [PCl2N]n

in refluxing THF for four days. The reaction yielded a brown IV-3 in 33 % yield.

1363

.613

93.7

1478

.5

1519

.6

1728

.4

1844

.3

1943

.4

2004

.3

2208

.9

2458

.7

2573

.6

1400 1600 1800 2000 2200 2400 2600m/z

1347

.7

1710

.51538

.6

1770

.5

2134

.2

1961

.3

2384

.0

2556

.9

141

The characterization of IV-3 was carried out by 31P NMR spectroscopy. Although

IV-1 had a poor solubility even in hot DMSO, a resonance was observed at -19.0 ppm d6-

DMSO as shown in Figure 4-8. The peak is broad and shifted up-field compared to

[PCl2N]n (Figure 3-2). In the 1H NMR spectrum (Figure 4-9), the peaks are very broad

compared to its hexa substituted trimer (Figure 2-8, Compound II-8). It is assumed that

the broader peaks in the substituted polymer are a result of different polymer chains

having different lengths and that the presence of water broadens peaks due to hydrogen-

bonding.

IV-3


P NO

O

N

N

nN

OH1. KH, THF, RT

2. [PCl2N]n, reflux, 4 d.

142


Figure 4-8. 31




143

The MALDI-ToF mass spectrum of the compound IV-3 is shown in Figure 4-10.

Four major distributions can be observed and they all have the expected interval of 233

Da, which is consistent with the PN3C10O2H8 repeat unit of the polymer, IV-3 and four

different sets of end groups for 4-12 mers.


4.2.2.2. Melt Polymerization Route of Pyridinoxy Cyclotriphosphazenes– A Preliminary Study

In considering the complexities that arose with the substitution reaction of

[PCl2N]n with pyridinoxides (Scheme 4-5), the melt ROP of pyridinoxy

cyclotriphosphazenes II-7, II-8, and II-9 has the potential to be a better route to

polymers. This is because the syntheses of pyridinoxytrimers (II-7, II-8 and II-9) occur

in high yields within a short time.

1105

.199

950.1

59

1183

.219

1338

.283

1571

.407

1416

.317

1649

.454

1804

.576

1882

.642

1010

.152

1087

.177

2115

.877

1320

.258

1553

.382

1786

.551

2037

.794

1243

.222

2019

.763

2349

.155

1475

.331

1165

.188

2271

.061

1708

.481

1942

.674

2582

.487

2486

.332

2174

.924

2815

.868

2719

.690

0

200

400

600

800

1000

1000 1250 1500 1750 2000 2250 2500 2750 3000 m/z

*

*

** *

*

*

**

Ø

Ø

Ø

Ø

Ø

Ø

Ø

Ø

Δ

ΔΔ

ΔΔ

Δ

Δ

Ψ Ψ Ψ ΨΨ

ΨΨ

Ψ

144

II-7 II-8 II-9

Figure 4-11. Structures of pyridinoxytrimers.

We attempted to reproduce the melt polymerization of II-7, II-8 and II-9 as

described in the literature. The process is similar to that already described for the ROP of

[PCl2N]3 to synthesize [PCl2N]n (Chapter III). A flame-sealed glass tube that contained

the pyridinoxytrimers was heated for the desired time with constant agitation. Table 4-2

summarizes the reaction conditions of all three compounds. Upon cooling the tube was

broken by percussion and in all three cases a black glassy solid was obtained. The solid

was then stirred with hexane for more than an hour.

Table 4-2. Melt polymerization of pyridinoxytrimers.

Although it was done earlier, we were unable to reproduce that procedure. Instead

of giving corresponding polymers, they all exhibited very broad 31P NMR resonances for

both compounds II-7 and II-9. The interesting feature noticed from 31P NMR was that

Compound Weight (g) Temperature (°C) Reaction time (h)Compound II-7 0.5 200 12Compound II-8 0.5 200 24Compound II-9 0.5 150 0.5

0.5 170 0.5

PN

PNP

N

O O

O

O

N

N

N

N

O

N

ON PN

PNP

N

O O

O

O

N

N

N

N

O

N

ON PN

PNP

N

O O

O

O

NN

N

N

O

N

ON

145

the original trimer peak had completely disappeared and the broad resonance was

observed in negative ppm. With compound II-8, there was no shift observed although the

reaction was carried out at 200 °C for a day.

Figure 4-12. 31P NMR spectra after direct melt polymerization reaction of II-7 (at 200 °C for 12 h) (a), and II-9 (at 170 °C for 30 min) (b).

31P_2_PYRIDINOXYPOLYMER_MELT_22611

100 80 60 40 20 0 -20 -40 -60 -80 -100Chemical Shift (ppm)

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Nor

mal

ized

Inte

nsity

31P_4_pyridinoxypolymer_melt_3511

100 80 60 40 20 0 -20 -40 -60 -80 -100Chemical Shift (ppm)

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Nor

mal

ized

Inte

nsity

(a)

(b)

4

le

ai

d

d

M

st

°C

te

.2.3. Therma

Therm

earn their the

ir atmospher

ecompositio

ecompositio

MRDT. Acc

tability. Only

C at both air

emperature o

Figure

al Analysis o

mal propertie

ermal stabili

re. D0.05 indi

on occurs and

on occurs.105

cording to th

y compound

r and inert at

of 800 °C.

4-13. Inert a

of Azolylme

es of few syn

ty. All the sc

icates the ini

d D1/2 repres

The maximu

he results sho

d IV-1 exhib

tmospheres.

atmosphere t

146

ethylphenoxy

nthesized po

cans were ru

itial decompo

sents the tem

um rate of d

own in Table

ited Td (D0.0

Again D1/2 w

thermogram

y and Pyridin

olymers were

un at 10 °C/m

osition temp

mperature at w

decompositio

e 4-3, not all

05) at a highe

was not obse

s of polymer

noxy Polyph

e also perfor

min under bo

perature (IDT

which 50%

on temperatu

l polymers h

er temperatur

erved at the h

rs IV-1, IV-

hosphazenes

rmed in orde

oth inert (N2

T) at which

of

ure is denote

had high ther

re up to at 27

heating

-2 and IV-3.

s

er to

2) and

5%

ed as

rmal

70

IV

re

p

fl

p

(-

CCC

Figure 4-

Table 4

Therm

V-3 are show

eorientationa

otential ener

lexible chain

olymers IV-

-66 °C) conf

Compound

Compound IVCompound IVCompound IV

14. Air atmo

4-3. Thermo

mal transition

wn in Figure

al freedom o

rgy barriers f

n requires a l

-1, IV-2 and

firming that t

D 0.05

V-1 290V-2 210V-3 148

Inert a

osphere therm

ogravimetric

n behaviors o

e 4-15. As al

of a polymer

for rotation a

lower potent

IV-3 exhibi

the substitut

D 1/2

-630327

atmosphere (°C

M

147

mograms of

parameters

obtained fro

ready discus

chain. The c

around the b

tial energy, a

ited values m

tion of bulky

D 0.0

331 273286 222343 149

C) A

MRDT

f polymers IV

of polymers

om DSC for p

ssed in Chap

chain flexibi

backbone ch

and it gives a

much higher

y groups dec

05 D 1/2

3 -2 6329 330

Air atmospher

V-1, IV-2 an

s IV-1, IV-2

polymers IV

pter III, Tg is

ility is depen

ain. A polym

a lower valu

than its prec

crease chain

300283339

re (°C) R

MRDT

nd IV-3.

2 and IV-3.

V-1, IV-2 an

s a measure

ndent upon t

mer with a m

ue of Tg. The

cursor, [PCl2

flexibility. T

Inert 63 542 315 8

Residue analysi

A

nd

of

the

more

e

2N]n

This

58358.1

is (%)

Air

148

happens due to the reduction of reorientational freedom of the phosphazene backbone.

All the polymers were found to be amorphous because they did not exhibit Tm or Tc

(crystalline temperature) values in their DSC curves.

Figure 4-15. DSC thermograms of polymers IV-1, IV-2 and IV-3.

Table 4-4. Degradation temperatures (Td), glass transition temperatures (Tg) and melting temperatures (Tm) of polymers from DSC.

25 50 75 100

End

o

Temperature (°C)

Compound IV-1 Compound IV-2 Compound IV-3

Phosphazene Polymers Td (D 0.05) (°C) Tg (°C) Tm (°C)Compound IV-1 290 96 -Compound IV-2 210 55 -Compound IV-3 148 50 -

149

4.3 Conclusion

A series of azolylmethylphenoxy and pyridinoxy substituted polyphosphazenes

were synthesized. All the azolylmethylphenoxy polymers were synthesized by

nucleophillic substitution polymerization using [PCl2N]n, which had been synthesized by

living cationic condensation polymerization. Some target polymers could not be

synthesized because full substitution of chlorides on [PCl2N]n could not be achieved.

With the pyridinoxy polymers, not only substitution but also melt polymerization

synthetic routes were tried. However, the melt polymerization was unsuccessful in

synthesizing polymers. The main characterization of the polymers was done by 31P NMR

and FTIR spectroscopies and MALDI/MS. Thermal properties of IV-1, IV-2 and IV-3

were examined by both TGA and DSC.

4.4 Experimental


Standard Schlenk techniques were used with all manipulations in dealing with

potassium hydride and all reactions were carried out under nitrogen atmosphere. 2-

hydroxypyridine, 3-hydroxypyridine and 4-hydroxypyridine were purchased from TCI

America Company. Synthetic details of compounds II-2, II-3, II-7, II-8 and II-9 are

given in Chapter II. Potassium hydride in mineral oil purchased from Aldrich was

filtered and washed with dry THF and stored in a glovebox. Tetrahydrofuran was dried

and deoxygenated by alumina column in the Pure SolvTM solvent system (Innovative

Technologies, Inc). All other reagents were used as received. NMR spectra were

recorded on a Varian Gemini 300 MHz and 500 MHz instruments using deuterated

150

DMSO, CD2Cl2 and CDCl3 as NMR solvents. The 1H and 13C NMR spectra were

referenced relative to the deuterated solvent. The 31P NMR was referenced with external

H3PO4 at δ 0 ppm. IR spectra were collected with a Bomem Excalibur Series with FTS

3000 model FTIR Spectrometer. Unless otherwise stated, spectra were recorded on pure

compounds. All FT-IR spectra were taken of a mixture of sample (1 mg) ground with

Thermo Spectra-Tech KBr powder (100 mg) that had been vibrated by a SchwingmÜble

vibrating mill for 20 seconds. Melting points were measured using Fluke Electrothermal

MEL-TEMP® connected to a digital thermometer (Model 51 II). Mass spectrometric

analysis was done by Vincenzo Scionti using the Matrix-Assisted Laser

Desorption/Ionization (MALDI) source and detector Time-of-Flight (ToF) detector on a

Bruker Reflex III MALDI-ToF instrument in the Department of Chemistry at The

University of Akron. Elemental analyses and ICP analysis were performed by University

of Illinois Microanalytical Laboratory. Thermo Gravimetric Analysis was done by a

QSeries – [Q500 – 0882 – TGA Q500@Mfg – tga] TGA instrument at a scanning rate of

10 °C/min under N2 and air atmosphere in the Department of Polymer Science and

Polymer Engineering at The University of Akron. Differential Scanning Calorimetry

(DSC) thermograms were obtained by using a Q2000 series instrument with a scanning

rate of 5 °C/min of both heating and cooling cycles under nitrogen atmosphere in the


4.4.2 Synthesis of poly{bis[4-(1H-1,2,4-triazol-1-ylmethyl)phenoxy]phosphazene} (IV-1) Potassium hydride (3.307 g, 82.44 mmol) was weighed into a 1 L Schlenk flask

inside the dry box and was dissolved in anhydrous tetrahydrofuran (50 mL) outside the

151

dry box. 4-(1H-1,2,4-triazol-1-ylmethyl)phenol (13.5 g, 76.1 mmol) dissolved in 65 mL

of anhydrous tetrahydrofuran was added dropwise to the KH/THF suspension.

Poly(dichlorophosphazene) (3.675 g, 31.71 mmol) dissolved in anhydrous

tetrahydrofuran (20 mL) was added into the reaction mixture under N2 purge. The

reaction mixture was refluxed at 80 °C for 6 days. After the mixture was cooled and

filtered, the precipitate was rinsed with (250 mL) to remove any salts. The precipitate was

washed separately with diethyl ether (100 mL) and acetone (50 mL) to remove reagents.

A fine yellow colored solid was obtained after the filtration and air-drying. Yield: 3.88 g,

9.86 mmol, 31 %. Anal. Calc. for (C18H16N7O2P)n: C, 58.53; H, 5.80; N, 21.72: P, 6.86.

Found: C, 52.00; H, 4.21; N, 20.72: P, 8.08. MALDI-ToF m/z: 1982, 2375, 2769, 3162,

3555, 3948, 4341, 4734, 5128, 5521, 5916, 6309, 6702. FTIR (KBr, cm-1): 1508 (C-C,

Ph), 1166 ( P=N), 943 (P-O-Ph). 1H NMR (300 MHz, DMSO-d6): δ 5.09 (s, 4H, CH2),

6.45 (bd, 4H, 2-H arom.), 6.63 (bd, 4H, 3-H arom.), 7.95 (s, 2H, 3-H), 8.49 (s, 2H, 5-H).

13C {1H} NMR (75 MHz, DMSO-d6): δ 151.7, 149.2, 144.0, 129.4, 128.5, 120.2, 51.4.

31P {1H} NMR (DMSO-d6): δ -18.8 ppm.

4.4.3 Synthesis of poly{bis[4-(1H-5-methyltetrazol-1-ylmethyl)phenoxy]phosphazene} (IV-2) Potassium hydride (0.601 g, 15.0 mmol) was weighed into a Schlenk flask inside

the dry box and was dissolved in anhydrous tetrahydrofuran (10 mL). 4-(1H-5-

methyltetrazol-1-ylmethyl)phenol (2.63 g, 13.84 mmol) dissolved in 35 mL of anhydrous

tetrahydrofuran was added dropwise. [PCl2N]n (0.668 g, 5.77 mmol) dissolved in

anhydrous tetrahydrofuran (20 mL) was added into the reaction mixture. The reaction

mixture was refluxed at 80 °C for 4 days. The reaction mixture was cooled and filtered.

152

The precipitate was stirred with water 200 mL) for 2 hours. Filtration and air-drying

yielded a light brown solid. Yield: 0.52 g, 1.23 mmol, 21 %. MALDI-ToF m/z: 1348,

1770, 2194, 2617. FTIR (KBr, cm-1): 1509 (C-C,Ph), 1168 ( P=N), 938 (P-O-Ph). 1H

NMR (300 MHz, DMSO-d6): δ 2.67 (s, 6H, CH3), 5.40 (bd, 4H, CH2), 6.68 (bd, 4H, 2-H

arom.), 6.95 (bd, 4H, 3-H arom.). 13C {1H} NMR (75 MHz, DMSO-d6): δ 152.1., 128.3,

120.4, 67.9, 49.9, 26.0, 8.4. 31P {1H} NMR (DMSO-d6): δ -19.4 ppm.

4.4.4 Synthesis of poly[bis(3-pyridinoxy)phosphazene] (IV-3)

Potassium hydride (0.626 g, 15.6 mmol) was weighed into a Schlenk flask inside

the dry box and was dissolved in anhydrous tetrahydrofuran (20 mL). 3-Pyridinol (1.369

g, 14.40 mmol) dissolved in 25 mL of anhydrous tetrahydrofuran was then added

dropwise using a cannula over a 30 min period. The resultant white colored reaction

mixture was refluxed at 80 °C for about 3 hours. The mixture was cooled down to 50 °C

and dichloropolyphosphazene (0.695 g, 6.00 mmol) dissolved in anhydrous

tetrahydrofuran (15 mL) was added into the reaction mixture using a cannula (over a 30

min). The reaction mixture was again refluxed at 80 °C for 4 days. The volatile

components were removed in vacuo and a yellow sticky rubber-like film was obtained.

The product was stirred with water (200 mL) overnight and was filtered. The film was

dried at 100 °C for 3 hours and it turned into a dark brown solid. The volatile

components were removed on the high vacuum line overnight resulting in a hard

polymer. Yield: 0.47 g, 2.0 mmol, 33 %. MALDI-ToF m/z: 950, 1183, 1416, 1649, 1883,

2116, 2349, 2582, 2818. FTIR (KBr, cm-1):1545 (C-C, Ph), 1181 (P=N), 951 (P-O-Ph).

1H NMR (300 MHz, DMSO-d6): δ 8.15 (bd, 2H, N=CH), 2-H arom.), 7.95 (bd, OC-

153

C(H)), 6.97 (bd, OC-C(H)=CH). 13C {1H} NMR (75 MHz, DMSO-d6): δ 153.6, 140.2,

138.0, 124.1, 122.0. 31P {1H} NMR (DMSO-d6): δ -19.0 ppm.

154

CHAPTER V

MEMBRANE CASTING, IMIDIZATION AND CONDUCTIVITY STUDIES

OF AZOLYLMETHYLPHENOXY PHOSPHAZENES

5.1 Introduction

5.1.1 PEMs based on N-Heterocycles

PEMs composed of N-containing heterocycles have been a field of interest for

scientists since the 1960s, and therefore, studies have been conducted on azoles,

including pyrazoles,132 imidazoles,132-138 benzimidazoles,9,139 triazoles,138,140-142 and

tetrazoles.143 The studies were aimed at replacing the water dependent proton

conductivity of PEMs and thereby developing high temperature functioning PEMs.

Because all of the azoles mentioned earlier generally have high melting points, they were

a successful substitute for water. The studies showed that the substitution of water with

these azoles lead to proton conductivities at higher temperatures (150 – 200 °C), which

were comparable to the conductivities of hydrated polymers.132

N-containing heterocycles form similar hydrogen bond networks compared to

water, and their transport properties are similar to those of water for a given temperature

relative to the melting point.132,140 But in order for N-containing heterocycles to be used

as a proton solvent in fuel cells, which is an open electrochemical system, they first need

to be immobilized in the polymer membrane to prevent any possible problems with

155

leaching. The conductivity of PEMs based on these heterocycles appears to be

completely dependent on the Grotthus mechanism, which is comprised of proton transfer

between heterocycles (protonated and nonprotonated) and hydrogen bond breaking and

forming processes (Figure 1-23).140 The proton transfer between protonated and

unprotonated nitrogens in triazoles is depicted in Figure 5-1.

Figure 5-1. Intermolecular proton transfer between neighboring protonated and nonprotonated triazoles.140

Kreuer was one of the pioneers in this field, and one of his earliest studies

involved intercalating pyrazole into a sulfonated polyetherketone. The conductivity of

this system increased with increasing pyrazole concentration, and the proton conductivity

obtained for the highest concentrations at 150 °C reached values that were comparable to

those of hydrated membranes around 50 °C.132 Studies involving imidazole were also

conducted in a few different ways. Initially, imidazole was intercalated into sulfonated

polyetherketone similarly to pyrazole, and the results obtained were of the same type,

however, imidazoles proved to have better transfer properties than pyrazole. Then

imidazole was intercalated into sulfanilic acid, and its proton conductivity was

investigated in the liquid state. In both imidazole containing systems described above, the

protonic defects were created by the protonation of imidazole which acted as a solvent for

the protons. As an alternative to those two, an H2SO4/imidazole system was prepared, and

NN

N HH

NN

NH

156

a higher proton conductivity was observed due to an increased number of defect protons

(HSO4-).132

As a first step towards full immobilization of imidazole as a proton solvent,

imidazole-terminated ethyleneoxide (EO) oligomers (Imi-x) were synthesized.134 The

molecular structure of (Imi-x) is shown in Figure 5-2. Imi-x systems exhibited dc

conductivities of 2-8 × 10-5 S cm-1 at 120 °C, once they were doped with triflic acid. For

water-free Imi-5, a conductivity of 2 × 10-3 S cm-1 was reported with 4.7 mol% acid

doping at 120 °C.134

Figure 5-2. Imidazole functionalized systems (Imi-x: x = 2-5).134

As an improvement to the previous studies, a fully polymer bound imidazole was

synthesized as the proton solvent comprising polystyrene with imidazole terminated

flexible side chains (Figure 5-3) were prepared. They had conductivities on the order of

10-3 S cm-1 at 200 °C, and this corresponded to a high mobility of protonic charge carriers

of 10-5 cm2 S-1.135 The conductivity of these systems was directly related to the ratio of

imidazoles to polymer support.

OON

NN

N

H

H

2-5

157

Figure 5-3. Imidazole bound to polystyrene via flexible spacers.135

Bozkurt and co-workers also started working with similar systems. When imidazole was

directly bound to the polymeric backbone, as in poly(4-vinyl-imidazole), P-4VI, the

reported conductivity was comparatively low (2 × 10-10 S cm-1 at 150 °C).136

Figure 5-4. Structure of P-4VI.136

As a continuation of the previous study, an anhydrous PEM was made by doping

poly(vinylphosphonic acid), PVPA with different stoichiometric ratios of imidazole-Im to

obtain PVPA x Im blend. They showed a maximum proton conductivity of 5 × 10-3

S cm-1 at 130 °C in anhydrous state when x = 2.137 This proves that incorporation of

flexible spacers supports high proton mobility over the imidazoles directly bound to the

polymer backbone.135

N NHn

NHN

NHN

NH

N

NNH

158

Figure 5-5. Structure of PVPA.137

Bozkurt and co-workers produced a new PEM by doping poly(styrene sulfonic

acid)—PSSA—with an imidazole derivative 1.12-diimidazol-2-yl-2,5,8,11-

tetraoxadodecane (imi3) as shown in Figure 5-6 to obtain different compositions of

PSSAimi3x . Once doped, PSSAimi30.5 had a conductivity of 1.5 × 10-4 S cm-1 at ambient

temperature.

Figure 5-6. Structures of PSSA (left) and imi3 (right).138

Benzimidazoles are another type of heterocycle used for PEM preparation. Honma

and co-workers reported the conductivity of an acid-base mixed material prepared by

mixing monododecylphosphate (MDP) and benzimidazole (BnIm). It exhibited 1 × 10-3

S cm-1 conductivity at 150 °C in the dry state. In this system, MDP acted as a proton

donor whereas BnIm acted as an acceptor for proton transport.139

S OOOH

n

NH

N H2C O

H2C

H2C O

H2C

NH

N

3

P

O

OHHO

n

159

MDP BnIm

Figure 5-7. Chemical structures of MDP (left) and BnIm (right).139

In the last decade, acid doped polybenzimidazoles have also been studied as

membranes for PEMS. Figure 5-8 illustrates two examples for these polymers. They

demonstrated very good properties, including appropriate proton conductivity for them to

be utilized in PEMFCs at temperatures as high as 200 °C without humidification. This

has been a vast area of research with plenty of benzimidazole derivatives, which have

become some of the better alternatives to Nafion®.9

PBI ABPBI

Figure 5-8. Structures of polybenzimidazole, PBI (left) and poly(2,5-benzimidazole), ABPBI (right).9

Numerous studies have been carried out using triazoles. Liu and co-workers

reported the proton conductivity of PEMs based on anhydrous sulfonated polysulfone

doped with triazole and they exhibited conductivity of 1.5 × 10-3 S cm-1 and 5 × 10-3 S

cm-1 at 100 °C and 140 °C respectively.142 Bozkurt and co-workers continued their

NH

N

N

NH

n

N

HN

n

N

HN

O P OHO

OH

160

studies on triazole systems by blending 1H-1,2,4-triazole with two different polymeric

host matrices, PVPA (Figure 5-5) and poly(2-acrylamido-2-methyl-1-propanesulfonic

acid (PAMPS, Figure 5-9), respectively, giving rise to PVPATrix and PAMPSTrix

films.140 In these systems, triazole was found to act as a plasticizer, and the PEM resulted

from PVPATri1.5 showed a maximum anhydrous conductivity of 2.3 × 10-3 S cm-1 at 120

°C whereas PAMPSTri2 exhibited 9.3 × 10-4 S cm-1 at 140 °C.140

Figure 5-9. Structure of PAMPS140

Another study aimed towards high temperature functioning PEMs was done by

doping poly(styrene sulfonic acid), PSSA, with triazole with several compositions to

obtain PSSATrix.138 PSSATrix reached 0.016 S cm-1 as the maximum conductivity at 150

°C, proving that triazole is a promising protogenic solvent in terms of proton

conductivity.138 As a continuation on these studies by Bozkurt and co-workers, triazole

and 3-amino-1,2,4-triazole (ATri) functionalized poly(glycidyl methacrylate)-PGMA

polymers were synthesized, and their suitability for PEMs were evaluated.141 The

polymers are shown in Figure 5-10. PGMA-ATri and PGMA-Tri were doped with

phosphoric and triflic acids separately using different molar ratios. PGMA-Tri 4 H3PO4

C

NH

n

CH3C CH3

CH2SO3H

O

161

showed the maximum proton conductivity in the anhydrous state of 9.0 × 10-3 S cm-1 at

150 °C whereas PGMA-ATri 2 H3PO4 exhibited 9.0 × 10-4 S cm-1 at 150 °C. There was

no significant proton conductivity for triflic acid doped samples.141

Figure 5-10. Structures of PGMA-ATri (left) and PGMA-Tri (right).141

Recently, phosphoric acid doped 5-aminotetrazole functional poly(glycidyl

methacrylate) – PGMAATet (Figure 5-11) was also investigated as a high temperature

operating PEM. It exhibited a conductivity of 0.01 S cm-1 at 150 °C in anhydrous state

when the dopant molar ratio was 4.143Although proton conduction occurred

predominantly between protonated and unprotonated tetrazole rings, proton hopping from

one N-H site to phosphate ions also contributed to the conductivity.143

O OHO

NN

N

nO O

HO

HN

n

NNHN

162

Figure 5-11. Structure of PGMAATet.143

Not only azoles but also pyridine derivatives have been investigated as proton

conductors (Figure 5-12).9 Poly(2-vinylpyridine), (P2VP) and poly(4- vinylpyridine),

(P4VP) doped with phosphoric acid have been studied by J. C. Lassegues. The former

exhibited 1 × 10-4 S cm-1 at 27 °C, and the latter was reported to have a higher

conductivity of 5.8 × 10-3 S cm-1 at 100 °C when doped with two moles of the acid.9,144

Figure 5-12. Structures of P2VP (left) and P4VP (right).9,144

nN

nN

O OHO

HN

HNN N

N

n

163

5.1.2 Imidization Studies

Polyimides have been used in blends over the years due to the excellent thermal

and chemical properties they exhibit. They also have excellent mechanical properties

suitable for a fuel cell environment because they can survive under severe conditions.145

This polymer itself has film forming properties. Imidization is a critical process in which

the resulting polymer exhibits high thermal, chemical and mechanical properties.

Although polyimides can be either aliphatic or aromatic, aromatic polyimidess are

used most because of their better thermal stability.146 They belong to a class of

heterocyclic polymers, and they exhibit some outstanding mechanical properties such as

excellent thermo-oxidative stability, high resistance to solvents, good processability,

good adhesion properties, and long term stability.146-149 Not only the polyimide, but also

the precursors for the polyimides, that is poly(amic acid)s-PAAs, are commercially

available. Dupont developed the first commercially available polyimide, known as

KaptonTM shown in Figure 5-13.145

Figure 5-13. KaptonTM polyimide.145

5.1.2.1 Synthesis of Poly(amic acid)s-PAAs

Synthesis of PAAs and/or copoly(amic acid)s can be done by

using different solvents, reaction temperatures, and times. Reaction temperatures and

NN O

O

OO

O

n

164

tim could range from 0 °C to RT and from 2 to 24 hours respectively. The self-catalyzed

cyclization to form polyimides cannot occur due to the strong interaction between the

amic acid and the basic solvent in which PAA is stored. The polar solvent forms strong

hydrogen-bonded complexes with the carboxylic acid groups of PAAs. However, PAAs

are usually stored in a cool place in a form of powder or solid polymers to prevent a

reverse reaction.146

Typically, aromatic polyimides are prepared by a two-step polycondensation

reaction.107 In the first stage, a pyromellitic dianhydride, PMDA and an oxydiamine,

ODA are reacted in an aprotic dipolar solvent, such as dimethylacetamide (DMAc),147,149

N,N-dimethylformamide (DMF) and NMP,146,148 in order to obtain the PAA as shown in

Scheme 5-1. This can be done at ambient temperature or below.

Scheme 5-1. General synthetic scheme of PAA107

5.1.2.2 Conversion of PAA into Polyimide

In the second part of the reaction, PAA is converted to polyimides as shown in

Scheme 5-2 in which an intramolecular cyclodehydration takes place.107 The KaptonTM

polyimide mentioned above (Figure 5-13) was also synthesized with this two-step

method as shown in Scheme 5-3.

OC

RC

OCC

O O

OO

+ H2N-R’-NH2n CR

CCC

O O

OO

NOHO H

R'H

NH

n

165

Scheme 5-2. Conversion of PAA into polyimide107

Scheme 5-3. Synthesis of KaptonTM polyimide via two-step thermal imidization

Imidization of PAAs to polyimides can be achieved both thermally as well as

chemically. In a thermal imidization, the viscous PAA is cast on a substrate and subject

to thermal treatment at a higher temperature for several hours. The temperature and the

time of imidization have been found to be different, depending on the structure of the

precursor. For example, with the imidizing condition of 300 °C for 1 hour some of the

PAAs based on 2,2´,6,6´-biphenyltetracarboxylic dianhydride imidized completely while

others required longer time.146 Other imidized conditions that have been reported are 300

CR

CN

CC

O O

OO

R' N

n

CR

CCC

O O

OO

NOHO H

R'H

NH

n

ONC

C OHO

O

CNO

CHOO

HH

n

NN O

O

OO

O

n

PAA(PMDA-ODA)

PI(PMDA-ODA)

166

°C for 1 hour and then 320 °C for ½ hour,150 260 °C for 3 hours149 and so on. This is the

preferred method when the final product is in a film or a coating form.

In chemical imidization, PAA is normally treated with a mixture of an aliphatic

carboxylic acid dianhydride such as acetic anhydride148 and trifluoroacetic anhydride,146

and a tertiary amine such as pyridine.146,148 The mechanism involves the reaction of the

tertiary amine with an anhydride, which is more susceptible to nucleophilic attack.

However, some techniques require a final treatment with high temperature near 300 °C (>

Tg) to complete the imidization.145

Over the years, researchers have worked with different types of dianhydrides and

diamines to synthesize the PAAs with desired properties such as dielectric materials for

microelectronics, high temperature adhesives, nonlinear optical materials, membranes for

separation technology, atomic oxygen resistant polymers and so on.105 In 1972, Tsimpris

and co-workers used benzene-1,2,4,5-tetracarboxyllic-1,2,4,5- dianhydride (PMDA) and

1,4-diaminobenzene (p-phenylenediamine, PPD) for this purpose.107 In 2004, Tiwari and

co-workers reported the synthesis of polyimide starting with the PMDA, 1,2,4,5-

tetracarboxyllic-1,2,4,5- dianhydride and ODA (4,4'-diaminodiphenyl ether).105 In 2006,

Sakayoki and co-workers reported the synthesis of polyimides from 2,2',6,6'-BPDA

(biphenyltetracarboxyllic dianhydride) with a range phenoxyanilines146 and so on.

In addition to this two-step polyimide synthetic route, there is also a one-step

method of polyimidization, and it involves heating a stoichiometric mixture of monomers

(a dianhydride and a diamine) in a high boiling solvent or a mixture of solvents such as

m-cresol, p-chlorophenol, nitrobenzene and dipolar aprotic amide solvents. Compared to

the two-step method, the latter suffers from a few drawbacks, including the toxicity of

167

solvents and a long reaction time (over 18 hours). Salicylic acid has become a better

solvent compared to m-cresol, p-chlorophenol and benzoic acid due to its high acidity,

low volatility, and excellent solvating power. In the presence of salicylic acid, complete

cyclization to polyimides occurred within 2 hours.148

In our attempts to synthesize a PEM which can function at a high temperature in

non-humidified conditions, we are currently working with inorganic-backbone

poly(organophosphazenes). The choice of polyphosphazene as the backbone was made

due to its inherent flexibility and high thermo-oxidative properties. The main focus of our

research is on using nitrogen containing heterocycles, azoles and pyridines as substituents

on the phosphazene backbone. The reason behind our decision was based on the results

of the previous conductivity studies performed on the azoles and pyridines. Thereby we

hypothesize these basic nitrogens can act as proton transfer sites across the membrane via

the hopping mechanism. One of the greatest advantages of phosphazene/N-heterocycle

systems over the Nafion® is their ability to function in the absence of water. This paves

the path towards high performing PEMFCs. Therefore, in this chapter, we describe the

methods of film casting, including solution and blade casting, imidization and doping

studies of phosphazene/N-heterocycle membranes.

168


In order to continue film casting, commercially available polyimide precursor,

poly(pyromellitic dianhydride-4,4'-oxydianiline) amic acid 15 wt% solution in NMP, was

used as a primary component to make the membrane, and the imidization was carried out

later in casting the membrane. From all the substituted phosphazenes synthesized, the

casting studies were primarily focused on triazole based systems, compounds II-5 and

IV-1. The triazole based systems have been studied towards possible PEMs due to their

higher degradation temperatures close to 300 °C compared to all the other compounds

(Figures 2-16, 2-17 and 4-12 and 4-13). They were also found to be stable at imidization

conditions at 200 °C for 3 hours. Compounds IV-1 was found to have limited

processibility due to its insolubility or partial solubility in common organic solvents. In

the search for a better solvent to cast them into films, N-methyl pyrrolidone (NMP) was

chosen. NMP acts not only as a solvent to dissolve the polymer, but also provides the

plasticizing effect required in film casting. The films obtained by solution casting on a

Teflon® surface became brittle over drying with several loadings of polymer, IV-1 to

NMP (5, 10, 15 and 20 %). Because IV-1 could not form films by themselves, a necessity

of a polymer matrix, which can act as a supporter, emerged. Polymer blending is the best

option to overcome this problem because it enhances the physical characteristics of the

final material over those of the individual components comprising the blend.106

169

5.2.1. Characterization

5.2.1.1 Thermal analysis

The thermal stability of PPA and polyimide films were recorded by

thermogravimetric analysis. All the scans were run at 10 °C/min under inert atmosphere

(N2). D0.05 indicates the initial decomposition temperature (IDT) at which 5%

decomposition occurs and D1/2 represents the temperature at which 50% of

decomposition occurs. The maximum rate of decomposition temperature is denoted as

MRDT.105 The thermal properties of the commercially available PAA was performed in

the lab in order to determine the optimal conditions required for possible maximum

imidization via thermal imidization. PAA undergoes an intramolecular cyclodehydration

on imidization as it loses water followed by the solvent, NMP as shown in Scheme 5-3.106

This cyclodehydration can be monitored by thermal analysis of PAA and PI. In order to

carry out thermal analysis, a film was cast from the commercial PAA on poly(ethylene

terephthalate) (PET) surface by heating it at 60 °C overnight to effect slow removal of the

solvent.105 The polymer solution concentration of 10% (w/w) was found to be suitable for

the preparation of good quality films.

The thermogram and the derivatogram for PAA are shown in Figure 5-14. It

clearly indicates four different steps of degradation. Table 5-1 explains the thermal

behavior at each region and the corresponding temperature responsible for each process.

The first step results from the evaporation of water and NMP, followed by the cyclization

of PPA to PI. This proceeds at around 215 °C. As can be seen from Figure 5-14, in the

second region polyimide is stable, and it extends up to ~550 °C. Region III corresponds

to

p

F

T

(a

ru

by

im

o the rapid d

olyimide is f

igure 5-14. I

Table 5-1. Di

The m

after overnig

unning TGA

y heating PA

midized film

Re

degradation o

formed.

Inert atmosp

ifferent regio

maximum po

ght heating a

A and FTIR. W

AA films at 2

m is shown in

egionI removIIIIIIV pyro

of backbone,

phere thermo

ons of the TG

ssible imidiz

at 60 °C) at d

With those t

200 °C for 3

n Figure 5-15

Thermal Bval of NMP, w

polyimide rapid deg

olyzed residue

170

, and above 7

ogram and de

GA curve of

zation was d

different tem

techniques, i

3 hours. The

5. Compared

Behaviorwater and cycliz

is stablegradationfrom the polym

700 °C, pyro

erivatogram

f poly(PMDA

determined b

mperatures fo

it was found

thermogram

d to Figure 5

Temperzation 215

550600

mer abo

olyzed residu

m of PAA(PM

A-ODA) am

by heating th

or several ho

d that imidiza

m and derivat

5-14, where i

rature (°C)5 ± 100 ± 100 ± 50

ove 700

ue of the

MDA-ODA)

mic acid.107

he PAA film

ours and by

ation takes p

togram of

its precursor

.

place

r, this

sh

ri

d

O

5

co

an

(C

(C

p

w

ab

fo

hows only on

igidity and h

egradation te

FigurODA) imide.

.2.1.2 FTIR

The d

onversion of

nd the appea

C=O) and 28

C=O), 1550

olyimide, th

which overlap

bsorption ba

or C-N stretc

ne region th

high mechani

emperature (

e 5-15. Inert

spectroscop

degree of imi

f PAA to pol

arance of the

800-3200 cm

cm-1 (C-NH

he strongest i

ps with the s

ands are obse

ching and 72

at is respons

ical properti

(D0.05) is abo

t atmosphere

py

idization is u

lyimide can b

e imide peak

m-1 (OH) for

H) and 3200-3

imide peak o

strong carbox

erved at 178

25 cm-1 for C

171

sible for the

ies of imidiz

out 520 °C.

e thermogram

usually moni

be followed

k. The PAA s

carboxylic a

3300 cm-1 (N

occurs at 172

xylic acid ba

0 cm-1 for C

C=O bending

backbone de

zation can be

m and deriva

itored by inf

by the disap

shows IR ab

acid groups

N-H) for the

20 cm-1 for C

and of the po

C=O asymme

g.

egradation. T

e seen becau

atogram of p

frared spectr

ppearance of

bsorptions at

and peaks at

e amide grou

C=O symme

oly(amic aci

etrical stretch

Therefore, th

se its

poly(PMDA

roscopy. The

f the amide p

1700 cm-1

t 1660 cm-1

up. In the

etrical stretch

id). Other im

hing, 1380 c

he

A-

e

peak

hing,

mide

cm-1

172

Because FTIR is an important tool in determining the imidization as stated above,

it was carried out starting with the PAA before the imidization. Figure 5-14 shows the IR

spectrum of PAA film with a broad peak for water at 2800-3200 cm-1 for O-H, at 1720

cm-1 for the C=O of the acid, at 1659 cm-1 for the amide peak (C=O), 3273 cm-1 (N-H)

and at 1544 cm-1 for C-NH. Finally, the thermal imidization of PAA was performed by

heating the PAA films to 200 °C, holding it at 200 °C for 1, 2, 3 and 12 hours for

comparison and slow cooling from 200 °C to room temperature. On imidization, the

appearance of the imide peak can be clearly observed from the IR spectra (Figure 5-14) at

726 (C=O bending), 1776 (asym C=O stretching), 1724 (sym C=O stretching) and 1378

cm-1 (C-N stretching). With heating at 200 °C for 1 hour, more than 90 % cyclization was

obtained. Increasing the heating time up to 3 hours seemed to provide optimum

imidization. The IR spectrum obtained after 12 hours was almost the same as the IR

spectrum obtained after 3 hours.

Ffo

igure 5-16. For 1, 2, 3 and

PI (3 h)

PI (2 h)

PI (1 h)

PAA

PI (12 h)

FTIR spectrad 12 hours.

a (absorbanc

173

ce mode) of

PAA and PI

Wavenumb

I after imidiz

ber (cm-1)

zation at 2000 °C

5

5

ca

(P

co

th

T

T

.2.2 Casting

.2.2.1 Soluti

Once

asting of IV

PPA) was al

ompositions

hickness 100

Thermal stabi

Table 5-2, IV

Fig

Studies

ion casting o

optimum co

-1 was carrie

so added as

, only 10 wt

0 µm upon im

ility of the b

V-1/PI has a

Figure

gure 5-18. In

of IV-1

onditions req

ed out in NM

a proton don

t% IV-1 cou

midization. W

blend was de

high therma

5-17. IV-1/

nert atmosph

174

quired for im

MP with PAA

nor into the b

ld be added

With 20 and

etermined by

al stability th

KaptonTM p

here thermog

midization we

A. In casting

blend. Out o

into PAA to

30 wt% IV-

y TGA. As sh

han IV-1 itse

olyimide ble

grams of IV-

ere determin

g, phenylpho

of three poss

o obtain a fle

-1, films bec

hown in Figu

elf.

end.

-1, PI and IV

ned, the solut

osphonic aci

sible

exible film o

came brittle.

ure 5-18 and

V-1/PI.

tion

d

of

d

5

su

u

N

N

so

th

re

o

im

II

Fso

.2.2.2 Soluti

Althou

upport to giv

sed in the so

NMP. As the

NMP, was use

olution casti

his polymer t

espectively.

f II-5, surpri

midization d

I-5 wt%, the

igure 5-19. Iolution casti

Table

ion casting o

ugh II-5 is s

ve the film fo

olution castin

polymer ma

ed as the pri

ng studies sh

to give flexi

Although D

isingly they

due to improp

e resultant fil

II-5/KaptonT

ng.

Polymer

IV-1PIIV-1/PI

5-2. TGA pa

of II-5

soluble in org

orming abili

ng of IV-1/P

atrix for II-5

imary compo

howed that b

ible films up

0.05 was expe

were compa

per temperat

lms became

TM polyimid

D 0.05

290517506

Inert

175

arameters of

ganic solven

ity to obtain

PI blend was

5, commercia

onent to mak

both 10 wt%

on imidizati

ected to be h

arably low. T

ture control.

brittle under

de composite

D 1/2 M---

atmosphere (°

f IV-1, PI an

nts for film c

II-5/PI com

s applied wit

ally availabl

ke the compo

% and 20 wt%

ion, having t

higher for im

This could b

All the oth

r imidizing c

e 10 wt% (le

ResidMRDT

331590604

C)

nd IV-1/PI

casting, PAA

mposite. The

th the use of

le PAA 15 w

osite membr

% of II-5 cou

thicknesses o

midized comp

e a result of

er times with

conditions.

ft) and 20 w

due analysis (%Inert635662

A was used a

same techni

f II-5 and PP

wt% solution

rane. Initial

uld be added

of 80 and 70

posites than

f partial

h increasing

wt% (right) fr

%)

as a

ique

PA in

in

d into

0 µm,

that

g the

rom

176

Figure 5-20. Inert atmosphere thermograms of II-5, PI, 20II-5/80PI and 10II-5/90PI.

Table 5-3. TGA parameters of II-5, PI, 10II-5/90PI and 20II-5/80PI.

5.2.2.3 Blade casting of II-5

Blade casting was carried out with 20 wt% II-5 and 80 wt% PAA. The film was

allowed to air dry at 50 °C for 12 hours to evaporate NMP, and then thermal imidization

was done by heating it to 200 °C, holding it at that temperature for 3 hours followed by

the slow cooling from 200 °C to room temperature to obtain a flexible II-5/PI composite

membrane 45 µm thick (Figure 5-21). The inert atmosphere thermogram of this

composite is shown in Figure 5-22 along with TGA parameters in Table 5-4. Compared

to the early solution cast films, the blade cast film exhibited a higher degradation

temperature than II-5, proving that the film has been completely imidized.

50

60

70

80

90

100

50 125 200 275 350 425 500 575 650 725 800

Wei

ght (

%)

Temparature (°C)

II-5PI20II-5/80PI10II-5/90PI

Trimer Residue analysisD 0.05 D 1/2 MRDT

II-5 355 - 362 71PI 517 - 590 5610II-5/90PI 340 - 594 5720II-5/80PI 295 - 564 54

Inert atmosphere (°C)

Figure

Fi

Wei

ght (

%)

e 5-21. II-5/

Table

igure 5-22. In

Trimer

II-5PIII-5/PI

50

60

70

80

90

100

50 125

/KaptonTM po

5-4. TGA p

nert atmosph

Inert atD 0.05

355 517 391

200 275 3

PI

II-5/PI

II-5

177

olyimide com

arameters of

here thermog

tmosphere (°C D 1/2 M - - -

50 425 500Tem

mposite from

f II-5, PI an

grams of PI

C) ResidMRDT 362 590 606

575 650 7mperature

m blade cast

nd II-5/PI.

, II-5/PI and

due Analysis (

715657

725 800(°C)

ting.

d II-5.

(%)

178

5.2.3 Acid Doping Levels, Thermal Stability and Proton Conductivity of Cast Films

5.2.3.1 Acid Doping Levels

The composite film resulted from blade casting, II-5/PI, was not doped and

therefore could not be used as a PEM. Therefore, a series of acid solutions (H3PO4,

H2SO4, and HNO3) were prepared as acidic dopants in different concentrations ranging

from 2 to10 mol/L as shown in Table 5-5. The doping was carried out by impregnating

the same sized composite films in acid solutions for 7 days at room temperature. Table 5-

6 summarizes the calculated acid doping level (%). With all the acids as the concentration

increases, amount of acid deposited on the membranes also gradually increased.

Compared to the effect from H3PO4 and H2SO4, HNO3 exhibited a significantly higher

effect in terms of acid deposition.

Table 5-5. Acid concentrations used in doping II-5/KaptonTM Polyimide composite.

Dopant Dopant MembraneConcentration (mol/L) Designation

2 2M H3PO4/II-5/PI4 4M H3PO4/II-5/PI

H3PO4 6 6M H3PO4/II-5/PI8 8M H3PO4/II-5/PI10 10M H3PO4/II-5/PI2 2M H2SO4/II-5/PI4 4M H2SO4/II-5/PI

H2SO4 6 6M H2SO4/II-5/PI8 8M H2SO4/II-5/PI10 10M H2SO4/II-5/PI2 2M HNO3/II-5/PI4 4M HNO3/II-5/PI

HNO3 6 6M HNO3/II-5/PI8 8M HNO3/II-5/PI10 10M HNO3/II-5/PI

179

Table 5-6. Acid doping levels of doped II-5/PI membranes.

* Acid-doping level = [(Wafter doped – Wbefore doped)/Wbefore doped] × 100 where W = weight

Membranes Weight Weight Acid-doping level Acid-doping level before doped (g) after doped (g) (%) (avg) (%)

2M H3PO4/II-5/PI 0.1314 0.1328 1.07 1.280.1260 0.1279 1.50

4M H3PO4/II-5/PI 0.1393 0.1415 1.58 1.690.116 0.1181 1.80

6M H3PO4/II-5T/PI 0.1349 0.1376 2.00 1.950.1148 0.1170 1.90

8M H3PO4/II-5/PI 0.1323 0.1361 2.87 2.680.1124 0.1152 2.50

10M H3PO4/II-5/PI 0.1337 0.1377 2.99 2.790.1138 0.1168 2.60

2M H2SO4/II-5/PI 0.1314 0.1328 1.07 1.060.1228 0.1241 1.06

4M H2SO4/II-5/PI 0.1363 0.1391 2.05 2.030.1193 0.1217 2.01

6M H2SO4/II-5/PI 0.1382 0.1414 2.32 2.260.1223 0.125 2.21

8M H2SO4/II-5/PI 0.1369 0.1411 3.07 3.060.1247 0.1285 3.05

10M H2SO4/II-5/PI 0.1375 0.1462 6.33 6.270.1142 0.1213 6.22

2M HNO3/II-5/PI 0.1390 0.1473 5.97 5.950.1182 0.1252 5.92

4M HNO3/II-5/PI 0.1367 0.1515 10.83 12.220.1132 0.1286 13.60

6M HNO3/II-5/PI 0.1389 0.1630 17.35 17.250.1143 0.1339 17.14

8M HNO3/II-5/PI 0.1366 0.1644 20.35 20.470.1112 0.1341 20.59

10M HNO3/II-5/PI 0.1365 0.1703 24.76 24.950.1122 0.1404 25.13

180

5.2.3.2 Thermal Analysis

The thermal stability of both undoped and doped membranes was monitored by

thermogravimetric analysis. Inert atmosphere thermograms of all of the membranes are

depicted in Figures 5-23 and 5-25 respectively. Degradation temperatures and

corresponding associated parameters obtained from these thermograms are summarized

in Table 5-7. The undoped II-5/PI showed the highest thermal stability, up to 391 °C.

Once doped, their degradation temperature (D0.05) was lower than that of the undoped,

and they follow the same order; as the concentration increases, the degradation

temperature also decreases. With II-5/PI doped with H3PO4 and H2SO4, a good thermal

stability as D0.05 value was obtained (higher than 300 °C). But HNO3 doped films

exhibited very low degradation temperatures compared to other two. Decomposition

temperature half way D1/2 was not reported for the temperature applied, which was

800 °C. The residue obtained after the complete decomposition of all was found to have

the highest residue percentage for 2M H2SO4/II-5/PI composite, which was 63 wt% in

inert atmosphere.

Fm

Fm

Fm

igure 5-23. Imembranes.

Figure 5-24. membranes.

igure 5-25. I

membranes.

Inert atmosp

Inert atmosp

Inert atmosp

phere thermo

phere thermo

phere thermo

181

ograms of un

ograms of un

ograms of un

ndoped and H

ndoped and

ndoped and H

H3PO4 doped

H2SO4 dope

HNO3 doped

d II-5/PI

ed II-5/PI

d II-5/PI

182

Table 5-7. Inert atmosphere TGA parameters of doped II-5/PI membranes.

5.2.3.3 Proton Conductivity

The proton conductivities of the doped IV-1/PI blend and both solution and blade

cast II-5/PI composites have not yet been measured. Because all the doped membranes

are to be used in high temperature fuel cells, a fuel cell facility which can operate at a

higher temperature needs to be utilized for measuring their proton conductivities. For a

chemically similar composite previously made in our lab, Tria-Trimer, C48H36N21P3 (40

wt%)/KaptonTM polyimide (60 wt%) doped with PPA (1:6 stoichiometric ratio of Tria-

Trimer to PPA) the maximum proton conductivity was recorded as 9.2 × 10-4 S cm-1 at

D 0.05 D 1/2 MRDTUndoped II-5/PI 391 - 607 572M H3PO4/II-5/PI 386 - 600 614M H3PO4/II-5/PI 384 - 596 626M H3PO4/II-5/PI 378 - 595 618M H3PO4/II-5/PI 364 - 597 6110M H3PO4/II-5/PI 348 - 597 582M H2SO4/II-5/PI 390 - 597 634M H3PO4/II-5/PI 387 - 601 626M H3PO4/II-5/PI 374 - 601 578M H3PO4/II-5/PI 367 - 599 5610M H3PO4/II-5/PI 315 - 602 592M HNO3/II-5/PI 273 - 597 554M HNO3/II-5/PI 151 - 597 556M HNO3/II-5/PI 139 - 595 548M HNO3/II-5/PI 127 - 592 5210M HNO3/II-5/PI 120 - 595 51

Inert atmosphere (°C)Membrane Residue analysis (%)

183

130 °C in anhydrous state. 151 Compared to other high temperature operating PEMs as

well as to Nafion® discussed in Chapter I, this value is relatively low.

5.3 Conclusion

In this chapter, film casting being the main focus, PAA was selected as the

polymeric support in casting phosphazene-based PEMs. The PAA can be imidized to

give good mechanical and thermal properties to the resulting blend and composite over

the individual components in the blend and composite. A series of heating cycles and IR

spectroscopy were used in determining the optimum conditions required for imidization.

Once imidization conditions were determined, IV-1/PI blend (10 wt% IV-1, 90 wt% PI)

and II-5/PI composites (10 wt% II-5, 90 wt% PI and 20 wt% II-5, 80 wt% PI via

solution casting and 20 wt% II-5, 80 wt% PI via blade casting) were cast. Except the

blade cast film, the rest were doped with PPA. The blade cast composite, II-5/PI

membrane was doped with H3PO4, H2SO4 and HNO3. With increasing acid

concentration, acid doping level also gradually increased. Compared to other two acids,

the latter caused a significanly lower degradation temperatures. The proton conductivity

of all the doped membranes is yet to be reported.

5.4 Experimental


The synthetic procedure of compounds II-5 and IV-I used in this chapter are

described in chapter II, synthesis of hexakis[4-(1H-1,2,4-triazol-1-

ylmethyl)phenoxy]cyclotriphophazene (II-5) and chapter IV, synthesis of poly{bis[4-

(1H-1,2,4-triazol-1-ylmethyl)phenoxy]phosphazene} (IV-1), respectively.

184

Poly(pyromellitic dianhydride-4,4’-oxydianiline) amic acid, 15 wt% solution in NMP

was purchased from Aldrich. N-methyl-2-pyrrolidone (NMP, 99.5%), purchased from

Alfa Aesar, was dried with Na2SO4 and 0.4 nm molecular sieves before use. IR spectra

were collected with a Bomem Excalibur Series with FTS 3000 model FTIR Spectrometer

in the Department of Polymer Science and Polymer Engineering at The University of

Akron. Thermo Gravimetric Analysis was done by a Q Series – [Q500 – 0882 – TGA

Q500@Mfg – tga] TGA at a scanning rate of 10 °C/min under N2 atmosphere in the


Blade casting was performed by the casting machine in the College of Polymer Science

and Polymer Engineering at The University of Akron.

5.4.2 Preparation of IV-1/KaptonTM Polyimide Blend doped with PPA via Solution Casting

The polymer solutions were cast on a poly(ethylene terephthalate) (PET) film (5 ×

5 cm2) by diluting 15 wt% PPA in NMP in to 10 wt% and dissolving IV-1 (0.050 g,

0.127 mmol) in wet NMP (0.45 g, 4.54 mmol) in order to obtain 0.5 g of IV-1solution in

10 wt% NMP which constituted 10 % of the final blend. The rest of the blend (90 %) was

prepared by dissolving PAA, 15 wt% (3.00 g) in wet NMP (1.5 g, 15.1 mmol) in order to

obtain 4.5 g 10 wt % PAA solution. The two blends were mixed together at room

temperature for 30 min to give the desired polymer blend (5.0 g in10 wt% NMP). PPA

(0.010 g, 63.6 mmol) solid was also added to the same mixture and stirred well at room

temperature for another 1and 1/2 hour. The resultant mixture was poured on to a PET

film, and the thickness of the PAA films was controlled by the thickness (1.00 mm) of

microscopic slides. Evaporation of the volatile components was done at 50 °C for 12

185

hours on a hot plate. The dried PAA film was released from the PET film directly and

clamped in all direction before the imidization process. Thermal imidization was done by

heating the PAA films to 200 °C, holding it at 200 °C for 3 hours followed by the slow

cooling from 200 °C to room temperature.

5.4.3 Preparation of II-5/KaptonTM Polyimide Composites doped with PPA via Solution Casting a). 10II-5/90PI

Compound II-5 (0.050 g, 0.0423 mmol) was dissolved in wet NMP (0.45 g, 4.54

mmol) in order to obtain 0.5 g of II-5 solution in 10 wt% NMP, which constituted 10 %

of the composite. The rest of the composite (90 %) was prepared by dissolving PAA (3 g)

in wet NMP (1.5 g, 15.1 mmol) in order to obtain 4.5 g of 10 wt% PAA solution. The two

solutions were mixed together at room temperature for another 30 min to get the desired

trimer composite (5.0 g, 10 wt% NMP). PPA (0.0402 g, 0.254 mmol) solid was also

added to the same mixture and stirred well at room temperature for 1 and ½ hour. The

resultant mixture was poured on to a PET film, and the thickness of the PAA films was

controlled by the thickness (1.00 mm) of microscopic slides. Evaporation of the volatile

components was done at 50 °C for 12 hours on a hot plate. The dried PAA film was

released from the PET film directly and clamped in all direction before the imidization

process. Thermal imidization was done by heating the PAA film to 200 °C, holding it at

200 °C for 3 hours followed by the slow cooling from 200 °C to room temperature.

186

b). 20II-5/80PI

Compound II-5 (0.1 g, 0.085 mmol) was dissolved in wet NMP (0.9 g, 5.70

mmol) in order to obtain 0.5 g of II-5 solution in 10 wt% NMP which constituted 20 %

of the composite. The rest of the composite (80 %) was prepared by dissolving PAA

(2.67 g) in wet NMP (1.33 g, 13.4 mmol) in order to obtain 4.5 g PAA solution. Two

solutions were mixed together at room temperature to give the desired trimer composite

(5.0 g, 10 wt% NMP). PPA (0.0803 g, 0.508 mmol) solid was also added to the same

mixture and stirred well at room temperature. The resultant mixture was poured on to a

PET film, and the thickness of the PAA film was controlled by the thickness (1.00 mm)

of microscopic slides. Evaporation of the volatile components was done at 50 °C for 12

hours on a hot plate. The dried PAA film was released from the PET film directly and

clamped in all direction before the imidization process. Thermal imidization was done by

heating the PAA film to 200 °C, holding it at 200 °C for 3 hours followed by the slow

cooling from 200 °C to room temperature.

5.4.4 Preparation of II-5/KaptonTM Polyimide Composite via Blade Casting

An amount equal to 20 wt% of compound II-5 (4.5 g, 3.81 mmol) was mixed

together with 80 wt% PAA, 15 wt% solution in dry NMP (115.42 g) in a planetary

centrifugal mixer (Thinky) at a speed of 2000 rpm at room temperature for 5 minutes.

The resultant mixture was cast by doctor blade in a casting machine onto a poly(ethylene

terephthalate) film at a rate of 10 cm /1 min. The doctor blade with a gap of 0.457 mm

was used to control the thickness of the membrane. The film was heated at 50 °C

overnight to evaporate the volatile components in the casting machine without any air

187

flow. The dried composite membrane (II-5/PAA) was released from the PET film

directly and clamped in all direction and the thermal imidization was carried out under

vacuum (200 °C for 3 hours) in order to obtain the II-5/PI composite. The undoped II-

5/PI composite membrane was obtained in an average thickness of 45 µm.

5.4.5 Preparation of acid doped II-5/KaptonTM Polyimide Composite

Blade cast II-5/PI blend film pieces of the size of 4 × 4 cm2 were dried at 110 °C

for 2 hours and the weight of each film was recorded (Wbefore doped). The films were

immersed into different acidic solutions, H2SO4, H3PO4 and HNO3 with the

concentrations of 2,4,6,8, and 10 mol/L at room temperature for 7 days. The films were

taken off from acid solutions and wiped with Kimwipes® and air dried for an hour (Wafter

doped).

188

CHAPTER VI

CONCLUDING REMARKS

The use of solid polymer electrolytes which can function at a high temperature in

a non-humidified environment has gained tremendous interest in the recent past in the

field of PEMFCs. The most viable electrolytes are N-heterocyclics substituted to

polyphosphazene backbone. When phosphazene backbone brings thermo-oxidative

stability, which is necessary to function at harsh conditions used in fuel cells,

heterocycles are responsible for proton transfer along the membrane. Due to the presence

of N-containing side groups, proton transfer occurs through proton hopping from

protonated to nonprotonated nitrogen atoms without the use of a vehicle. This is the key

in operating at a higher temperature in a non-humidified state in contrast to Nafion® in

which proton conduction depends on the external humidification.

The focus of our study was to find a better alternative to currently available PEMs

by using polyphosphazene as the backbone and azoles and pyridines as substituents. In

trying to reach that goal, three different types of azoles (pyrazole, 1,2,4-triazole and 5-

methyltetrazole) and three different pyridinols (2-pyridinol, 3-pyridinol and 4-pyridinol)

were chosen. According to previous studies, researchers have found that as the

substituent of interest connects to the backbone polymer through chains, they exhibit

higher conductivity. Therefore, the azoles previously mentioned were reacted with 4-

hydroxybenzyl alcohol to obtain the corresponding azolylmethylphenols

189

(compounds II-1, II-2, II-3). They were successfully substituted to

hexachlorocyclotriphosphazene in order to obtain compounds II-4 through II-6, and

compounds IV-7 through IV-9 were synthesized with the use of respective pyridinols. In

order to carry out substitutions with chloropolymer, the synthesis of chloropolymer was

also done in the laboratory by living cationic polycondensation as a one-pot in situ

method. Upon the completion of that step, the substitutions were carried out in order to

obtain compounds IV-1, IV-2 and IV-3 with starting materials II-2, II-3 and 3-pyridinol,

respectively.

The initial studies performed on both trimers and polymers resulted in brittle

films. Consequently, a polymeric supporter, poly(PMDA-ODA) amic acid 15 wt%

solution in NMP was employed. Only the compounds based on triazole systems (II-5 and

IV-1) were able to maintain thermal stability under the film casting conditions (200 °C

for 3 hours) in order to obtain imidized flexible films. The degree of imidization was

monitored via TGA and FTIR. But only IV-1/PI blend (10 wt% IV-1, 90 wt% PI) and II-

5/PI composites (10 wt% II-5, 90 wt% PI and 20 wt% II-5, 80 wt% PI via solution

casting and 20 wt% II-5, 80 wt% PI via blade casting) were able to be cast to obtain

suitable films. The best imidized film was obtained from blade casting, and it was

successfully doped with H2SO4, H3PO4 and HNO3 whereas all the other solution cast

films were doped with phenylphosphonic acid. The acid doping studies indicated that the

films get doped with increasing acid concentration gradually.

However, we have not met the final goal of our study. Although we were able to

synthesize azolylmethylphenoxy phosphazenes and fabricate them into flexible

membranes followed by successful acid doping studies, in order to determine whether the

190

synthesized membranes are better candidates for PEMs, it is necessary to measure the

proton conductivities of those synthesized membranes.

191

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200

APPENDICES

201

APPENDIX A

SUPPLEMENTARY MATERIAL FOR THE X-RAY CRYSTAL STRUCTURE OF

C10H10N2O (II-1)

Table A-1. Crystal data and structure refinement for II-1. Empirical formula C10H10N2O Formula weight 174.20 Temperature 273(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group Pc Unit cell dimensions a = 7.8400(18) Å α = 90° b = 11.148(3) Å β = 95.647(3)° c = 20.680(5) Å γ = 90° Volume 1798.6(7) Å3 Z 8 Density (calculated) 1.287 Mg/m3 Absorption coefficient 0.086 mm-1 F(000) 736 Crystal size 0.45 x 0.19 x 0.14 mm3 Theta range for data collection 1.83 to 26.30°. Index ranges -9<=h<=9, -13<=k<=13, -25<=l<=25 Reflections collected 13095 Independent reflections 7017 [R(int) = 0.0638] Completeness to theta = 26.30° 99.9 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9884 and 0.9624 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 7017 / 2 / 473 Goodness-of-fit on F2 1.033 Final R indices [I>2sigma(I)] R1 = 0.0688, wR2 = 0.1744 R indices (all data) R1 = 0.0719, wR2 = 0.1814 Absolute structure parameter -0.1(11) Largest diff. peak and hole 0.629 and -0.267 e.Å-3

202

Table A-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-1. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ O(1) 679(2) 3514(2) 2952(1) 27(1) O(2) -3412(2) 11061(2) 1308(1) 28(1) O(3) 5578(2) 8504(2) 2876(1) 29(1) O(4) 11273(2) 6061(2) 1120(1) 28(1) N(1) 7953(3) 1061(2) 3537(1) 23(1) N(2) 7181(3) 67(2) 3740(1) 24(1) N(3) 3529(3) 8653(2) 592(1) 24(1) N(4) 2549(3) 7728(2) 358(1) 25(1) N(5) -1383(3) 6047(2) 3591(1) 24(1) N(6) -449(3) 5081(2) 3820(1) 27(1) N(7) 4077(3) 3600(2) 682(1) 24(1) N(8) 4903(3) 2625(2) 481(1) 25(1) C(1) 9243(4) 686(3) 4501(1) 34(1) C(2) 9174(4) 1451(2) 3979(1) 31(1) C(3) 7364(3) 1598(3) 2902(1) 27(1) C(4) 5605(3) 2168(2) 2897(1) 22(1) C(5) 4167(4) 1573(2) 2601(1) 23(1) C(6) 2544(4) 2036(2) 2614(1) 26(1) C(7) 2318(3) 3125(2) 2940(1) 22(1) C(8) 7988(4) -165(2) 4324(1) 28(1) C(9) 5380(3) 3257(2) 3199(1) 25(1) C(10) 3747(4) 3737(2) 3227(1) 24(1) C(11) -1792(3) 10655(2) 1270(1) 22(1) C(12) -1344(4) 9569(2) 1582(1) 24(1) C(13) 294(4) 9111(2) 1568(1) 24(1) C(14) 1526(3) 9712(2) 1249(1) 22(1) C(15) 3282(4) 9179(2) 1226(1) 27(1) C(16) 4672(4) 8968(3) 181(1) 34(1) C(17) 4457(4) 8220(3) -342(1) 36(1) C(18) 3117(4) 7457(3) -210(1) 28(1) C(19) 1079(4) 10809(2) 946(1) 23(1) C(20) -566(4) 11272(2) 954(1) 24(1) C(21) 3981(3) 8078(2) 2929(1) 23(1) C(22) 2732(4) 8707(2) 3231(1) 25(1) C(23) 1096(4) 8225(2) 3239(1) 26(1) C(24) 688(3) 7111(2) 2959(1) 22(1) C(25) -1084(3) 6581(2) 2957(1) 26(1) C(26) -2485(4) 6404(2) 4006(1) 30(1)

203

Table A-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-1 (continued) C(27) -2297(4) 5647(3) 4536(1) 34(1) C(28) 3574(4) 6975(2) 2645(1) 25(1) C(29) 1945(3) 6496(2) 2662(1) 23(1) C(30) -1026(4) 4844(2) 4392(1) 28(1) C(31) 2863(4) 3225(3) -303(1) 34(1) C(32) 2869(4) 3983(3) 228(1) 31(1) C(33) 4646(3) 4172(2) 1314(1) 24(1) C(34) 6380(3) 4734(2) 1303(1) 22(1) C(35) 7857(4) 4109(2) 1532(1) 24(1) C(36) 9465(3) 4563(2) 1462(1) 24(1) C(37) 9647(3) 5681(2) 1176(1) 23(1) C(38) 6577(3) 5875(2) 1027(1) 24(1) C(39) 8188(4) 6344(2) 965(1) 25(1) C(40) 4151(4) 2396(2) -117(1) 27(1) ________________________________________________________________________ Table A-3. Bond lengths [Å] and angles [°] for II-1. O(1)-C(7) 1.359(3) O(1)-H(1A) 0.8200 O(2)-C(11) 1.358(3) O(2)-H(2A) 0.8200 O(3)-C(21) 1.354(3) O(3)-H(3) 0.8200 O(4)-C(37) 1.359(3) O(4)-H(4) 0.8200 N(5)-C(26) 1.336(3) N(5)-N(6) 1.361(3) N(5)-C(25) 1.480(3) N(6)-C(30) 1.334(4) N(7)-C(32) 1.337(4) N(7)-N(8) 1.353(3) N(7)-C(33) 1.481(3) N(8)-C(40) 1.341(3) C(1)-C(2) 1.373(4) C(1)-C(8) 1.390(4) C(1)-H(1) 0.9300 C(2)-H(2) 0.9300 C(3)-C(4) 1.517(4) C(3)-H(3A) 0.9700 C(3)-H(3B) 0.9700 C(4)-C(9) 1.384(4)

C(4)-C(5) 1.397(4) C(5)-C(6) 1.376(4) C(5)-H(5) 0.9300 C(6)-C(7) 1.407(4) C(6)-H(6) 0.9300 C(7)-C(10) 1.394(4) C(8)-H(8) 0.9300 C(9)-C(10) 1.394(4) C(9)-H(9) 0.9300 C(10)-H(10) 0.9300 C(11)-C(20) 1.395(4) C(11)-C(12) 1.401(3) C(12)-C(13) 1.385(4) C(12)-H(12) 0.9300 C(13)-C(14) 1.393(4) C(13)-H(13) 0.9300 C(14)-C(19) 1.403(4) C(14)-C(15) 1.505(4) C(15)-H(15A) 0.9700 C(15)-H(15B) 0.9700 C(16)-C(17) 1.363(4) C(16)-H(16) 0.9300 C(17)-C(18) 1.399(4)

204

Table A-3. Bond lengths [Å] and angles [°] for II-1 (continued) C(17)-H(17) 0.9300 C(18)-H(18) 0.9300 C(19)-C(20) 1.391(4) C(19)-H(19) 0.9300 C(20)-H(20) 0.9300 C(21)-C(28) 1.386(4) C(21)-C(22) 1.400(4) C(22)-C(23) 1.392(4) C(22)-H(22) 0.9300 C(23)-C(24) 1.395(4) C(23)-H(23) 0.9300 C(24)-C(29) 1.392(4) C(24)-C(25) 1.509(4) C(25)-H(25A) 0.9700 C(25)-H(25B) 0.9700 C(26)-C(27) 1.381(4) C(26)-H(26) 0.9300 C(27)-C(30) 1.393(4) C(27)-H(27) 0.9300 C(28)-C(29) 1.388(4) C(28)-H(28) 0.9300 C(29)-H(29) 0.9300 C(30)-H(30) 0.9300 C(31)-C(32) 1.385(4) C(31)-C(40) 1.394(4) C(31)-H(31) 0.9300 C(32)-H(32) 0.9300 C(33)-C(34) 1.499(4) C(33)-H(33A) 0.9700 C(33)-H(33B) 0.9700 C(34)-C(35) 1.394(4) C(34)-C(38) 1.409(4) C(35)-C(36) 1.379(4) C(35)-H(35) 0.9300 C(36)-C(37) 1.392(4) C(36)-H(36) 0.9300 C(37)-C(39) 1.396(4) C(38)-C(39) 1.384(4) C(38)-H(38) 0.9300 C(39)-H(39) 0.9300 C(40)-H(40) 0.9300

C(7)-O(1)-H(1A) 109.5 C(11)-O(2)-H(2A) 109.5 C(21)-O(3)-H(3) 109.5 C(37)-O(4)-H(4) 109.5 C(2)-N(1)-N(2) 111.6(2) C(2)-N(1)-C(3) 128.4(2) N(2)-N(1)-C(3) 120.0(2) C(8)-N(2)-N(1) 104.7(2) C(16)-N(3)-N(4) 111.4(2) C(16)-N(3)-C(15) 128.1(2) N(4)-N(3)-C(15) 120.5(2) C(18)-N(4)-N(3) 105.2(2) C(26)-N(5)-N(6) 111.9(2) C(26)-N(5)-C(25) 128.1(2) N(6)-N(5)-C(25) 120.0(2) C(30)-N(6)-N(5) 104.3(2) C(32)-N(7)-N(8) 111.5(2) C(32)-N(7)-C(33) 127.8(2) N(8)-N(7)-C(33) 120.4(2) C(40)-N(8)-N(7) 104.9(2) C(2)-C(1)-C(8) 104.2(3) C(2)-C(1)-H(1) 127.9 C(8)-C(1)-H(1) 127.9 N(1)-C(2)-C(1) 108.0(3) N(1)-C(2)-H(2) 126.0 C(1)-C(2)-H(2) 126.0 N(1)-C(3)-C(4) 112.4(2) N(1)-C(3)-H(3A) 109.1 C(4)-C(3)-H(3A) 109.1 N(1)-C(3)-H(3B) 109.1 C(4)-C(3)-H(3B) 109.1 H(3A)-C(3)-H(3B) 107.9 C(9)-C(4)-C(5) 118.8(2) C(9)-C(4)-C(3) 121.4(2) C(5)-C(4)-C(3) 119.8(2) C(6)-C(5)-C(4) 121.4(2) C(6)-C(5)-H(5) 119.3 C(4)-C(5)-H(5) 119.3 C(5)-C(6)-C(7) 119.6(3) C(5)-C(6)-H(6) 120.2 C(7)-C(6)-H(6) 120.2 O(1)-C(7)-C(10) 123.8(2) O(1)-C(7)-C(6) 116.7(2) C(10)-C(7)-C(6) 119.5(2) N(2)-C(8)-C(1) 111.5(2)

205

Table A-3. Bond lengths [Å] and angles [°] for II-1 (continued) N(2)-C(8)-H(8) 124.3 C(1)-C(8)-H(8) 124.3 C(4)-C(9)-C(10) 120.9(2) C(4)-C(9)-H(9) 119.5 C(10)-C(9)-H(9) 119.5 C(9)-C(10)-C(7) 119.8(2) C(9)-C(10)-H(10) 120.1 C(7)-C(10)-H(10) 120.1 O(2)-C(11)-C(20) 123.7(2) O(2)-C(11)-C(12) 117.0(2) C(20)-C(11)-C(12) 119.3(2) C(13)-C(12)-C(11) 119.9(2) C(13)-C(12)-H(12) 120.0 C(11)-C(12)-H(12) 120.0 C(12)-C(13)-C(14) 121.4(2) C(12)-C(13)-H(13) 119.3 C(14)-C(13)-H(13) 119.3 C(13)-C(14)-C(19) 118.4(2) C(13)-C(14)-C(15) 120.3(2) C(19)-C(14)-C(15) 121.3(2) N(3)-C(15)-C(14) 112.8(2) N(3)-C(15)-H(15A) 109.0 C(14)-C(15)-H(15A) 109.0 N(3)-C(15)-H(15B) 109.0 C(14)-C(15)-H(15B) 109.0 H(15A)-C(15)-H(15B) 107.8 N(3)-C(16)-C(17) 107.7(3) N(3)-C(16)-H(16) 126.1 C(17)-C(16)-H(16) 126.1 C(16)-C(17)-C(18) 104.7(2) C(16)-C(17)-H(17) 127.6 C(18)-C(17)-H(17) 127.6 N(4)-C(18)-C(17) 110.9(2) N(4)-C(18)-H(18) 124.6 C(17)-C(18)-H(18) 124.6 C(20)-C(19)-C(14) 120.7(2) C(20)-C(19)-H(19) 119.7 C(14)-C(19)-H(19) 119.7 C(19)-C(20)-C(11) 120.3(2) C(19)-C(20)-H(20) 119.8 C(11)-C(20)-H(20) 119.8 O(3)-C(21)-C(28) 116.9(2)

O(3)-C(21)-C(22) 123.6(2) C(28)-C(21)-C(22) 119.5(2) C(23)-C(22)-C(21) 119.8(2) C(23)-C(22)-H(22) 120.1 C(21)-C(22)-H(22) 120.1 C(22)-C(23)-C(24) 120.8(2) C(22)-C(23)-H(23) 119.6 C(24)-C(23)-H(23) 119.6 C(29)-C(24)-C(23) 118.6(2) C(29)-C(24)-C(25) 119.9(2) C(23)-C(24)-C(25) 121.5(2) N(5)-C(25)-C(24) 112.4(2) N(5)-C(25)-H(25A) 109.1 C(24)-C(25)-H(25A) 109.1 N(5)-C(25)-H(25B) 109.1 C(24)-C(25)-H(25B) 109.1 H(25A)-C(25)-H(25B) 107.8 N(5)-C(26)-C(27) 107.6(3) N(5)-C(26)-H(26) 126.2 C(27)-C(26)-H(26) 126.2 C(26)-C(27)-C(30) 104.2(2) C(26)-C(27)-H(27) 127.9 C(30)-C(27)-H(27) 127.9 C(21)-C(28)-C(29) 120.3(3) C(21)-C(28)-H(28) 119.9 C(29)-C(28)-H(28) 119.9 C(28)-C(29)-C(24) 121.0(2) C(28)-C(29)-H(29) 119.5 C(24)-C(29)-H(29) 119.5 N(6)-C(30)-C(27) 112.0(2) N(6)-C(30)-H(30) 124.0 C(27)-C(30)-H(30) 124.0 C(32)-C(31)-C(40) 103.9(2) C(32)-C(31)-H(31) 128.1 C(40)-C(31)-H(31) 128.1 N(7)-C(32)-C(31) 108.0(3) N(7)-C(32)-H(32) 126.0 C(31)-C(32)-H(32) 126.0 N(7)-C(33)-C(34) 111.2(2) N(7)-C(33)-H(33A) 109.4 C(34)-C(33)-H(33A) 109.4 N(7)-C(33)-H(33B) 109.4 C(34)-C(33)-H(33B) 109.4 H(33A)-C(33)-H(33B) 108.0 C(35)-C(34)-C(38) 117.9(2)

206

Table A-3. Bond lengths [Å] and angles [°] for II-1 (continued) C(35)-C(34)-C(33) 120.7(2) C(38)-C(34)-C(33) 121.3(2) C(36)-C(35)-C(34) 121.2(2) C(36)-C(35)-H(35) 119.4 C(34)-C(35)-H(35) 119.4 C(35)-C(36)-C(37) 120.4(2) C(35)-C(36)-H(36) 119.8 C(37)-C(36)-H(36) 119.8 O(4)-C(37)-C(36) 116.8(2)

O(4)-C(37)-C(39) 123.7(2) C(36)-C(37)-C(39) 119.4(2) C(39)-C(38)-C(34) 121.1(2) C(39)-C(38)-H(38) 119.5 C(34)-C(38)-H(38) 119.5 C(38)-C(39)-C(37) 119.9(2) C(38)-C(39)-H(39) 120.1 C(37)-C(39)-H(39) 120.1 N(8)-C(40)-C(31) 111.7(2) N(8)-C(40)-H(40) 124.2 C(31)-C(40)-H(40) 124.2

Symmetry transformations used to generate equivalent atoms:

207

APPENDIX B


C9H9N3O (II-2)

Table B-1. Crystal data and structure refinement for II-2.

Empirical formula C9H9N3O Formula weight 175.19 Temperature 100(2) K Wavelength 1.54178 Å Crystal system Orthorhombic Space group Pca2(1) Unit cell dimensions a = 8.4986(8) Å α = 90° b = 5.4668(5) Å β = 90° c = 18.2326(17) Å γ = 90° Volume 847.09(14) Å3 Z 4 Density (calculated) 1.374 Mg/m3 Absorption coefficient 0.773 mm-1 F(000) 368 Crystal size 0.20 x 0.08 x 0.05 mm3 Theta range for data collection 4.85 to 65.93°. Index ranges -10<=h<=9, -4<=k<=6, -14<=l<=21 Reflections collected 2726 Independent reflections 1130 [R(int) = 0.0218] Completeness to theta = 65.93° 98.3 % Absorption correction Numerical Max. and min. transmission 0.9594 and 0.9449 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 1130 / 1 / 119 Goodness-of-fit on F2 0.933 Final R indices [I>2sigma(I)] R1 = 0.0253, wR2 = 0.0665 R indices (all data) R1 = 0.0253, wR2 = 0.0665 Absolute structure parameter 0.5(2) Largest diff. peak and hole 0.120 and -0.165 e.Å-3

208

Table B-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for bw. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ O(1) 1099(1) 2986(2) 2570(1) 22(1) N(1) 2358(1) 1509(2) 5994(1) 18(1) N(2) 1552(1) 3577(2) 6184(1) 22(1) N(3) 768(1) 356(2) 6870(1) 22(1) C(1) 1656(1) 2594(3) 3256(1) 19(1) C(2) 1223(2) 549(2) 3672(1) 20(1) C(3) 1840(2) 246(2) 4365(1) 20(1) C(4) 2874(2) 1953(3) 4668(1) 19(1) C(5) 3556(2) 1561(3) 5419(1) 21(1) C(6) 623(2) 2787(3) 6710(1) 24(1) C(7) 2701(2) 4299(2) 3547(1) 20(1) C(8) 3290(2) 3986(3) 4250(1) 20(1) C(9) 1878(2) -365(3) 6406(1) 20(1) Table B-3. Bond lengths [Å] and angles [°] for II-2. O(1)-C(1) 1.3553(18) O(1)-H(1) 0.8400 N(1)-C(9) 1.3339(19) N(1)-N(2) 1.3661(15) N(1)-C(5) 1.462(2) N(2)-C(6) 1.316(2) N(3)-C(9) 1.3271(19) N(3)-C(6) 1.3660(19) C(1)-C(7) 1.392(2) C(1)-C(2) 1.399(2) C(2)-C(3) 1.379(2) C(2)-H(2) 0.9500 C(3)-C(4) 1.396(2) C(3)-H(3) 0.9500 C(4)-C(8) 1.393(2) C(4)-C(5) 1.502(2) C(5)-H(5A) 0.9900 C(5)-H(5B) 0.9900 C(6)-H(6) 0.9500 C(7)-C(8) 1.388(2) C(7)-H(7) 0.9500

C(8)-H(8) 0.9500 C(9)-H(9) 0.9500 C(1)-O(1)-H(1) 109.5 C(9)-N(1)-N(2) 109.87(12) C(9)-N(1)-C(5) 129.16(12) N(2)-N(1)-C(5) 120.97(11) C(6)-N(2)-N(1) 102.33(11) C(9)-N(3)-C(6) 102.52(12) O(1)-C(1)-C(7) 117.90(13) O(1)-C(1)-C(2) 122.28(13) C(7)-C(1)-C(2) 119.82(14) C(3)-C(2)-C(1) 119.45(13) C(3)-C(2)-H(2) 120.3 C(1)-C(2)-H(2) 120.3 C(2)-C(3)-C(4) 121.50(13) C(2)-C(3)-H(3) 119.3 C(4)-C(3)-H(3) 119.3 C(8)-C(4)-C(3) 118.46(14) C(8)-C(4)-C(5) 120.95(13)

209

Table B-3. Bond lengths [Å] and angles [°] for II-2 (continued) C(3)-C(4)-C(5) 120.57(13) N(1)-C(5)-C(4) 112.81(11) N(1)-C(5)-H(5A) 109.0 C(4)-C(5)-H(5A) 109.0 N(1)-C(5)-H(5B) 109.0 C(4)-C(5)-H(5B) 109.0 H(5A)-C(5)-H(5B) 107.8 N(2)-C(6)-N(3) 114.90(12)

N(2)-C(6)-H(6) 122.5 N(3)-C(6)-H(6) 122.5 C(8)-C(7)-C(1) 119.94(13) C(8)-C(7)-H(7) 120.0 C(1)-C(7)-H(7) 120.0 C(7)-C(8)-C(4) 120.83(13) C(7)-C(8)-H(8) 119.6 C(4)-C(8)-H(8) 119.6 N(3)-C(9)-N(1) 110.37(13) N(3)-C(9)-H(9) 124.8 N(1)-C(9)-H(9) 124.8

Table B-4. Anisotropic displacement parameters (Å2x 103) for II-2. The anisotropic displacement factor exponent takes the form: -2p2[ h2 a*2U11 + ... + 2 h k a* b* U12 ] ________________________________________________________________________ U11 U22 U33 U23 U13 U12 ________________________________________________________________________ O(1) 26(1) 24(1) 17(1) 2(1) -4(1) 0(1) N(1) 20(1) 19(1) 15(1) -2(1) 0(1) 1(1) N(2) 26(1) 20(1) 21(1) -3(1) 0(1) 4(1) N(3) 23(1) 26(1) 17(1) -3(1) 1(1) -3(1) C(1) 18(1) 21(1) 17(1) -2(1) 1(1) 4(1) C(2) 20(1) 20(1) 19(1) -2(1) 1(1) -2(1) C(3) 21(1) 20(1) 20(1) 1(1) 4(1) 0(1) C(4) 18(1) 22(1) 17(1) -2(1) 2(1) 2(1) C(5) 19(1) 25(1) 18(1) -2(1) 1(1) 0(1) C(6) 23(1) 26(1) 23(1) -8(1) 1(1) 2(1) C(7) 23(1) 19(1) 20(1) 2(1) 2(1) 0(1) C(8) 20(1) 19(1) 22(1) -3(1) -1(1) 0(1) C(9) 21(1) 21(1) 18(1) -1(1) -2(1) -1(1) ________________________________________________________________________ Table B-5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for II-2. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ H(1) 465 1868 2458 33 H(2) 510 -622 3477 24 H(3) 1555 -1155 4643 24 H(5A) 4141 -5 5424 25

210

Table B-5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for II-2. H(5B) 4314 2889 5526 25 H(6) -94 3827 6960 29 H(7) 3010 5676 3263 25 H(8) 3986 5173 4449 24 H(9) 2273 -1986 6371 24 ________________________________________________________________________


211

APPENDIX C


C9H10N4O (II-3a)

Table C-1. Crystal data and structure refinement for II-3a.

Empirical formula C9H10N4O Formula weight 190.21 Temperature 100(2) K Wavelength 0.71073 Å Crystal system Triclinic Space group P-1 Unit cell dimensions a = 8.933(3) Å α = 82.468(5)° b = 9.818(3) Å β = 77.736(5)° c = 10.736(4) Å γ = 81.594(5)° Volume 905.3(5) Å3 Z 4 Density (calculated) 1.396 Mg/m3 Absorption coefficient 0.097 mm-1 F(000) 400 Crystal size 0.34 x 0.19 x 0.05 mm3 Theta range for data collection 1.95 to 26.30°. Index ranges -11 ≤ h ≤ 11, -12 ≤ k ≤ 12, -13 ≤ l ≤ 13 Reflections collected 7080 Independent reflections 3642 [R(int) = 0.0417] Completeness to theta = 26.30° 99.0 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9951 and 0.9676 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 3642 / 0 / 257 Goodness-of-fit on F2 1.025 Final R indices [I>2sigma(I)] R1 = 0.0659, wR2 = 0.1581 R indices (all data) R1 = 0.0844, wR2 = 0.1677 Largest diff. peak and hole 0.472 and -0.281 e.Å-3

212

Table C-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-3a. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ O(1) 14401(2) 6283(2) 2814(2) 27(1) N(1) 7057(2) 7324(2) 3588(2) 23(1) N(2) 7398(3) 8147(2) 2470(2) 32(1) N(3) 6363(3) 9222(2) 2554(2) 31(1) N(4) 5355(2) 9110(2) 3701(2) 25(1) C(1) 12868(3) 6160(2) 3029(2) 20(1) C(2) 11853(3) 7092(2) 3781(2) 22(1) C(3) 10283(3) 7023(3) 4018(2) 23(1) C(4) 9677(3) 6031(2) 3518(2) 20(1) C(5) 10696(3) 5090(2) 2786(2) 20(1) C(6) 12281(3) 5145(2) 2537(2) 19(1) C(7) 7962(3) 5947(3) 3786(3) 25(1) C(8) 5799(3) 7926(3) 4320(2) 22(1) C(9) 5027(3) 7345(3) 5592(3) 28(1) O(2) 12382(2) 393(2) 4220(2) 23(1) N(5) 8197(2) 3175(2) 263(2) 19(1) N(6) 7774(2) 4314(2) 902(2) 22(1) N(7) 6278(2) 4448(2) 1195(2) 24(1) N(8) 5700(2) 3426(2) 763(2) 24(1) C(10) 11819(3) 897(2) 3131(2) 19(1) C(11) 10274(3) 824(3) 3154(2) 23(1) C(12) 9637(3) 1379(3) 2099(2) 23(1) C(13) 10526(3) 2017(2) 1014(2) 19(1) C(14) 12074(3) 2072(2) 1000(2) 19(1) C(15) 12729(3) 1506(2) 2046(2) 19(1) C(16) 9832(3) 2672(3) -133(2) 24(1) C(17) 6920(3) 2646(2) 190(2) 20(1) C(18) 6880(3) 1372(3) -411(3) 28(1) ________________________________________________________________________

213

Table C-3. Bond lengths [Å] and angles [°] for II-3a. O(1)-C(1) 1.360(3) N(6)-N(5)-C(16) 120.0(2) N(1)-C(8) 1.335(3) N(7)-N(6)-N(5) 105.9(2) N(1)-N(2) 1.360(3) N(6)-N(7)-N(8) 111.4(2) N(1)-C(7) 1.485(3) C(17)-N(8)-N(7) 105.3(2) N(2)-N(3) 1.296(3) C(8)-N(1)-N(2) 108.9(2) N(3)-N(4) 1.365(3) C(8)-N(1)-C(7) 130.5(2) N(4)-C(8) 1.313(3) N(2)-N(1)-C(7) 120.5(2) C(1)-C(2) 1.397(3) N(3)-N(2)-N(1) 106.0(2) C(1)-C(6) 1.399(3) N(2)-N(3)-N(4) 110.3(2) C(2)-C(3) 1.382(4) C(8)-N(4)-N(3) 106.7(2) C(3)-C(4) 1.394(4) O(1)-C(1)-C(2) 117.8(2) C(4)-C(5) 1.393(3) O(1)-C(1)-C(6) 122.8(2) C(4)-C(7) 1.510(3) C(2)-C(1)-C(6) 119.4(2) C(5)-C(6) 1.392(3) C(3)-C(2)-C(1) 120.2(2) C(8)-C(9) 1.475(4) C(2)-C(3)-C(4) 121.2(2) O(2)-C(10) 1.375(3) C(3)-C(4)-C(5) 118.4(2) N(5)-C(17) 1.341(3) C(3)-C(4)-C(7) 121.2(2) N(5)-N(6) 1.353(3) C(5)-C(4)-C(7) 120.4(2) N(5)-C(16) 1.463(3) C(6)-C(5)-C(4) 121.2(2) N(6)-N(7) 1.297(3) C(5)-C(6)-C(1) 119.7(2) N(7)-N(8) 1.365(3) N(1)-C(7)-C(4) 112.2(2) N(8)-C(17) 1.322(3) N(4)-C(8)-N(1) 108.1(2) C(10)-C(11) 1.387(4) N(4)-C(8)-C(9) 126.1(2) C(10)-C(15) 1.390(3) C(11)-C(12)-C(13) 120.9(2) C(11)-C(12) 1.387(4) C(14)-C(13)-C(12) 118.7(2) C(12)-C(13) 1.393(3) C(14)-C(13)-C(16) 119.7(2) C(13)-C(14) 1.389(3) C(12)-C(13)-C(16) 121.6(2) C(13)-C(16) 1.521(3) C(13)-C(14)-C(15) 120.9(2) C(14)-C(15) 1.390(3) C(10)-C(15)-C(14) 119.7(2) C(17)-C(18) 1.489(4) N(5)-C(16)-C(13) 111.0(2)

N(8)-C(17)-N(5) 108.8(2) N(1)-C(8)-C(9) 125.7(2) N(8)-C(17)-C(18) 125.4(2) C(17)-N(5)-N(6) 108.6(2) N(5)-C(17)-C(18) 125 C(17)-N(5)-C(16) 131.2(2) C(11)-C(10)-C(15) 120.0(2) O(2)-C(10)-C(11) 117.7(2) C(12)-C(11)-C(10) 119.8(2) O(2)-C(10)-C(15) 122.2(2)

214

Table C-4. Anisotropic displacement parameters (Å2x 103) for II-3a. The anisotropic displacement factor exponent takes the form: -2π2[ h2 a*2U11 + ... + 2 h k a* b* U12 ] ________________________________________________________________________ U11 U22 U33 U23 U13 U12 ________________________________________________________________________ O(1) 20(1) 22(1) 41(1) -10(1) -6(1) 1(1) N(1) 22(1) 22(1) 25(1) -1(1) -3(1) -2(1) N(2) 30(1) 29(1) 30(1) 7(1) -2(1) 3(1) N(3) 27(1) 28(1) 32(1) 6(1) -2(1) 5(1) N(4) 22(1) 22(1) 29(1) 0(1) -5(1) 0(1) C(1) 21(1) 13(1) 26(1) 4(1) -8(1) 0(1) C(2) 24(1) 13(1) 30(1) -2(1) -9(1) -1(1) C(3) 26(1) 14(1) 28(1) -1(1) -6(1) 4(1) C(4) 20(1) 14(1) 23(1) 6(1) -7(1) 1(1) C(5) 23(1) 12(1) 24(1) 4(1) -9(1) -1(1) C(6) 23(1) 11(1) 23(1) 0(1) -7(1) 3(1) C(7) 22(1) 17(1) 33(1) 6(1) -5(1) 0(1) C(8) 21(1) 21(1) 27(1) -3(1) -8(1) -3(1) C(9) 26(1) 25(1) 31(2) -3(1) -2(1) -1(1) O(2) 22(1) 20(1) 26(1) 3(1) -8(1) 1(1) N(5) 22(1) 13(1) 20(1) 3(1) -4(1) 1(1) N(6) 23(1) 15(1) 27(1) 1(1) -6(1) 1(1) N(7) 22(1) 18(1) 31(1) 0(1) -7(1) 2(1) N(8) 22(1) 18(1) 31(1) 0(1) -6(1) -1(1) C(10) 23(1) 12(1) 23(1) -2(1) -9(1) 3(1) C(11) 22(1) 19(1) 25(1) 8(1) -3(1) -2(1) C(12) 17(1) 23(1) 29(1) 4(1) -6(1) -3(1) C(13) 21(1) 11(1) 23(1) 1(1) -4(1) 1(1) C(14) 22(1) 11(1) 23(1) 1(1) -3(1) 0(1) C(15) 16(1) 13(1) 26(1) -4(1) -4(1) 0(1) C(16) 19(1) 24(1) 24(1) 4(1) -3(1) 3(1) C(17) 22(1) 16(1) 22(1) 6(1) -6(1) -1(1) C(18) 34(2) 20(1) 30(1) -1(1) -5(1) -4(1) ________________________________________________________________________ Table C-5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for II-3a. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ H(1) 14881 5765 2258 41 H(2A) 12244 7775 4131 26

215

Table C-5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for II-3a (continued) H(3) 9604 7662 4531 28 H(5) 10302 4399 2450 24 H(6) 12961 4495 2036 23 H(7A) 7738 5322 3214 30 H(7B) 7636 5546 4681 30 H(9A) 4170 8016 5948 42 H(9B) 5769 7143 6166 42 H(9C) 4630 6489 5508 42 H(2) 13341 175 4024 35 H(11) 9654 396 3890 28 H(12) 8580 1324 2117 28 H(14) 12694 2503 266 23 H(15) 13794 1534 2019 22 H(16A) 10397 3453 -569 28 H(16B) 9948 1980 -751 28 H(18A) 7013 558 208 42 H(18B) 7714 1303 -1166 42 H(18C) 5884 1415 -670 42


216

APPENDIX D


C9H10N4O (II-3b)

Table D-1.Crystal data and structure refinement for II-3b.

Empirical formula C9H10N4O Formula weight 190.21 Temperature 100(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group P2(1)/c Unit cell dimensions a = 7.401(2) Å α = 90° b = 16.035(4) Å β = 104.841(5)° c = 8.239(2) Å γ = 90° Volume 945.1(4) Å3 Z 4 Density (calculated) 1.337 Mg/m3 Absorption coefficient 0.093 mm-1 F(000) 400 Crystal size 0.32 x 0.10 x 0.10 mm3 Theta range for data collection 2.54 to 26.30°. Index ranges -9 ≤ h ≤ 9, -19 ≤ k ≤ 19, -10 ≤ l ≤ 10 Reflections collected 7349 Independent reflections 1915 [R(int) = 0.0363] Completeness to theta = 26.30° 99.9 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9907 and 0.9707 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 1915 / 0 / 129 Goodness-of-fit on F2 1.052 Final R indices [I>2sigma(I)] R1 = 0.0391, wR2 = 0.1028 R indices (all data) R1 = 0.0507, wR2 = 0.1069 Largest diff. peak and hole 0.268 and -0.171 e.Å-3

217

Table D-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-3b. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ O(1) 3119(1) 3599(1) -877(1) 31(1) N(1) 11551(2) 3788(1) 3444(1) 23(1) N(2) 11925(2) 4588(1) 3230(2) 27(1) N(3) 12278(2) 4261(1) 5911(2) 27(1) N(4) 11740(2) 3573(1) 5015(2) 28(1) C(1) 5004(2) 3520(1) -207(2) 25(1) C(2) 5623(2) 2886(1) 947(2) 28(1) C(3) 7520(2) 2787(1) 1675(2) 27(1) C(4) 8825(2) 3308(1) 1239(2) 25(1) C(5) 8186(2) 3939(1) 69(2) 26(1) C(6) 6295(2) 4054(1) -640(2) 26(1) C(7) 10889(2) 3203(1) 2041(2) 27(1) C(8) 12386(2) 4870(1) 4806(2) 25(1) C(9) 12957(2) 5740(1) 5292(2) 35(1) Table D-3. Bond lengths [Å] and angles [°] for II-3b. O(1)-C(1) 1.3681(17) N(1)-N(4) 1.3116(16) N(1)-N(2) 1.3340(16) N(1)-C(7) 1.4721(17) N(2)-C(8) 1.3337(18) N(3)-N(4) 1.3298(17) N(3)-C(8) 1.3516(18) C(1)-C(2) 1.387(2) C(1)-C(6) 1.396(2) C(2)-C(3) 1.387(2) C(3)-C(4) 1.392(2) C(4)-C(5) 1.394(2) C(4)-C(7) 1.510(2) C(5)-C(6) 1.384(2) C(8)-C(9) 1.483(2) N(4)-N(1)-N(2) 114.17(11) N(4)-N(1)-C(7) 122.52(12)

N(2)-N(1)-C(7) 123.24(11) C(8)-N(2)-N(1) 101.96(11) N(4)-N(3)-C(8) 106.62(12) N(1)-N(4)-N(3) 105.75(11) O(1)-C(1)-C(2) 117.97(13) O(1)-C(1)-C(6) 122.20(13) C(2)-C(1)-C(6) 119.83(13) C(1)-C(2)-C(3) 120.02(13) C(2)-C(3)-C(4) 120.81(13) C(3)-C(4)-C(5) 118.60(13) C(3)-C(4)-C(7) 120.74(13) C(5)-C(4)-C(7) 120.65(13) C(6)-C(5)-C(4) 121.11(13) C(5)-C(6)-C(1) 119.61(13) N(1)-C(7)-C(4) 111.61(11) N(2)-C(8)-N(3) 111.50(13) N(2)-C(8)-C(9) 124.46(14) N(3)-C(8)-C(9) 124.0

218

Table D-4. Anisotropic displacement parameters (Å2x 103) for II-3b. The anisotropic displacement factor exponent takes the form: -2π2[ h2 a*2U11 + ... + 2 h k a* b* U12 ] ________________________________________________________________________ U11 U22 U33 U23 U13 U12 ________________________________________________________________________ O(1) 27(1) 40(1) 25(1) 5(1) 1(1) -5(1) N(1) 23(1) 24(1) 23(1) 2(1) 3(1) 2(1) N(2) 27(1) 23(1) 28(1) 2(1) 5(1) 2(1) N(3) 23(1) 30(1) 25(1) -1(1) 1(1) 1(1) N(4) 27(1) 31(1) 23(1) 2(1) 2(1) 0(1) C(1) 26(1) 28(1) 18(1) -4(1) 2(1) -3(1) C(2) 33(1) 25(1) 25(1) 0(1) 6(1) -6(1) C(3) 36(1) 21(1) 22(1) 1(1) 2(1) -1(1) C(4) 29(1) 23(1) 21(1) -5(1) 4(1) 0(1) C(5) 28(1) 25(1) 25(1) -1(1) 4(1) -4(1) C(6) 30(1) 25(1) 21(1) 2(1) 3(1) -1(1) C(7) 31(1) 25(1) 24(1) -4(1) 4(1) 3(1) C(8) 18(1) 28(1) 27(1) 0(1) 3(1) 4(1) C(9) 34(1) 30(1) 39(1) -5(1) 6(1) 1(1) Table D-5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2 x 103) for II-3b. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ H(1) 2923 3889 -1755 47 H(2) 4748 2520 1240 34 H(3) 7933 2358 2479 32 H(5) 9062 4295 -247 32 H(6) 5877 4495 -1417 31 H(7A) 11132 2624 2458 33 H(7B) 11594 3297 1186 33 H(9A) 13889 5921 4709 53 H(9B) 13497 5769 6508 53 H(9C) 11862 6106 4980 53 ________________________________________________________________________ Symmetry transformations used to generate equivalent atoms:

219

APPENDIX E


C60H54N15O6P3 (II-4)

Table E-1. Crystal data and structure refinement for II-4.

Empirical formula C60H54N15O6P3 Formula weight 1174.09 Temperature 100(2) K Wavelength 0.71073 Å Crystal system Triclinic Space group P-1 Unit cell dimensions a = 8.4999(9) Å α = 89.554(2)° b = 16.3633(18) Å β = 82.848(2)° c = 20.111(2) Å γ = 85.779(2)° Volume 2767.9(5) Å3 Z 2 Density (calculated) 1.409 Mg/m3 Absorption coefficient 0.177 mm-1 F(000) 1224 Crystal size 0.27 x 0.09 x 0.02 mm3 Theta range for data collection 1.61 to 26.30°. Index ranges -10<=h<=10, -20<=k<=20, -25<=l<=25 Reflections collected 19613 Independent reflections 11004 [R(int) = 0.0381] Completeness to theta = 26.30° 97.8 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9968 and 0.9546 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 11004 / 0 / 757 Goodness-of-fit on F2 1.026 Final R indices [I>2sigma(I)] R1 = 0.0436, wR2 = 0.0971 R indices (all data) R1 = 0.0759, wR2 = 0.1124 Largest diff. peak and hole 0.321 and -0.398 e.Å-3

220

Table E-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-4. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ P(1) 5126(1) 2076(1) 4673(1) 20(1) P(2) 2164(1) 1725(1) 5263(1) 21(1) P(3) 2474(1) 2871(1) 4249(1) 20(1) O(1) 6610(2) 2374(1) 4976(1) 23(1) O(2) 5999(2) 1404(1) 4169(1) 24(1) O(3) 1396(2) 2010(1) 5988(1) 26(1) O(4) 1446(2) 867(1) 5230(1) 25(1) O(5) 1804(2) 3806(1) 4300(1) 24(1) O(6) 2082(2) 2674(1) 3517(1) 23(1) N(1) 4034(2) 1624(1) 5226(1) 22(1) N(2) 1423(2) 2330(1) 4747(1) 22(1) N(3) 4324(2) 2813(1) 4286(1) 21(1) N(4) 7323(3) 3531(1) 7959(1) 29(1) N(5) 6461(3) 3049(2) 8385(1) 45(1) N(6) 7388(3) 1495(1) 956(1) 31(1) N(7) 6423(3) 1856(2) 529(1) 39(1) N(8) 2711(2) 1672(1) 9014(1) 26(1) N(9) 1422(3) 1227(1) 9135(1) 33(1) N(10) 2221(2) -379(1) 2175(1) 27(1) N(11) 3262(3) 204(1) 2031(1) 32(1) N(12) 1368(2) 5444(1) 7269(1) 27(1) N(13) 2463(2) 4884(1) 7472(1) 29(1) N(14) 3848(3) 4314(1) 656(1) 29(1) N(15) 2931(3) 3954(2) 259(1) 42(1) C(1) 6526(3) 2780(1) 5592(1) 21(1) C(2) 5326(3) 3364(2) 5811(1) 25(1) C(3) 5362(3) 3747(2) 6423(1) 26(1) C(4) 6577(3) 3552(1) 6804(1) 23(1) C(5) 7775(3) 2960(2) 6569(1) 26(1) C(6) 7739(3) 2573(1) 5965(1) 24(1) C(7) 6600(3) 4006(2) 7456(1) 30(1) C(8) 7534(4) 2675(2) 8737(2) 52(1) C(9) 9057(4) 2901(2) 8533(1) 46(1) C(10) 8883(3) 3452(2) 8037(1) 35(1) C(11) 6503(3) 1571(1) 3492(1) 21(1) C(12) 7820(3) 2003(2) 3318(1) 24(1) C(13) 8309(3) 2127(2) 2646(1) 28(1)

221

Table E-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-4 (continued) C(14) 7506(3) 1824(1) 2152(1) 24(1) C(15) 6187(3) 1391(2) 2346(1) 26(1) C(16) 5680(3) 1259(1) 3018(1) 24(1) C(17) 8088(3) 1986(2) 1424(1) 35(1) C(18) 6016(3) 1231(2) 182(1) 39(1) C(19) 6691(3) 485(2) 380(1) 35(1) C(20) 7556(3) 673(2) 874(1) 30(1) C(21) 2082(3) 1840(2) 6580(1) 23(1) C(22) 2411(3) 1050(2) 6784(1) 27(1) C(23) 3017(3) 925(2) 7392(1) 27(1) C(24) 3275(3) 1583(2) 7785(1) 23(1) C(25) 2952(3) 2371(2) 7558(1) 30(1) C(26) 2343(3) 2505(2) 6954(1) 29(1) C(27) 3916(3) 1450(2) 8447(1) 28(1) C(28) 594(3) 1575(2) 9680(1) 35(1) C(29) 1326(3) 2236(2) 9901(1) 38(1) C(30) 2680(3) 2287(2) 9459(1) 33(1) C(31) 1688(3) 444(1) 4609(1) 23(1) C(32) 2940(3) -137(1) 4494(1) 25(1) C(33) 3147(3) -556(2) 3887(1) 27(1) C(34) 2124(3) -395(2) 3410(1) 26(1) C(35) 877(3) 204(2) 3543(1) 27(1) C(36) 657(3) 627(2) 4143(1) 26(1) C(37) 2322(3) -886(2) 2766(1) 30(1) C(38) 2863(3) 532(2) 1460(1) 33(1) C(39) 1589(3) 167(2) 1244(1) 37(1) C(40) 1211(3) -411(2) 1716(1) 34(1) C(41) 1818(3) 4253(1) 4898(1) 22(1) C(42) 2822(3) 4874(2) 4888(1) 26(1) C(43) 2777(3) 5356(2) 5456(1) 27(1) C(44) 1739(3) 5218(2) 6025(1) 26(1) C(45) 748(3) 4584(2) 6024(1) 26(1) C(46) 779(3) 4091(2) 5460(1) 25(1) C(47) 1629(3) 5813(2) 6605(1) 30(1) C(48) 1967(3) 4762(2) 8113(1) 32(1) C(49) 581(3) 5244(2) 8329(1) 40(1) C(50) 230(3) 5666(2) 7775(1) 36(1) C(51) 2869(3) 2962(1) 2916(1) 22(1) C(52) 3818(3) 3615(2) 2884(1) 26(1) C(53) 4497(3) 3869(2) 2259(1) 27(1) C(54) 4233(3) 3491(2) 1672(1) 26(1) C(55) 3308(3) 2822(2) 1723(1) 25(1)

222

Table E-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-4 (continued) C(56) 2641(3) 2549(2) 2342(1) 24(1) C(57) 4959(3) 3801(2) 999(1) 29(1) C(58) 3580(3) 5134(2) 672(1) 38(1) C(59) 2427(4) 5323(2) 264(1) 48(1) C(60) 2074(4) 4570(2) 22(1) 48(1) Table E-3. Bond lengths [Å] and angles [°] for II-4. P(1)-N(1) 1.574(2) P(1)-O(1) 1.5765(17) P(1)-O(2) 1.5810(16) P(1)-N(3) 1.5882(19) P(2)-N(1) 1.578(2) P(2)-O(4) 1.5773(18) P(2)-O(3) 1.5811(16) P(2)-N(2) 1.5834(19) P(3)-N(2) 1.5706(19) P(3)-N(3) 1.579(2) P(3)-O(6) 1.5884(16) P(3)-O(5) 1.5931(16) O(1)-C(1) 1.401(3) O(2)-C(11) 1.406(3) O(3)-C(21) 1.406(3) O(4)-C(31) 1.417(3) O(5)-C(41) 1.413(3) O(6)-C(51) 1.403(3) N(4)-N(5) 1.346(3) N(4)-C(10) 1.351(3) N(4)-C(7) 1.441(3) N(5)-C(8) 1.333(4) N(6)-C(20) 1.352(3) N(6)-N(7) 1.362(3) N(6)-C(17) 1.451(3) N(7)-C(18) 1.334(4) N(8)-C(30) 1.349(3) N(8)-N(9) 1.355(3) N(8)-C(27) 1.464(3) N(9)-C(28) 1.334(3) N(10)-C(40) 1.340(3) N(10)-N(11) 1.355(3)

N(10)-C(37) 1.452(3) N(11)-C(38) 1.334(3) N(12)-C(50) 1.347(3) N(12)-N(13) 1.355(3) N(12)-C(47) 1.459(3) N(13)-C(48) 1.324(3) N(14)-C(58) 1.345(3) N(14)-N(15) 1.349(3) N(14)-C(57) 1.453(3) N(15)-C(60) 1.322(4) C(1)-C(6) 1.371(3) C(1)-C(2) 1.379(3) C(2)-C(3) 1.389(3) C(2)-H(2) 0.9500 C(3)-C(4) 1.379(3) C(3)-H(3) 0.9500 C(4)-C(5) 1.392(3) C(4)-C(7) 1.515(3) C(5)-C(6) 1.379(3) C(5)-H(5) 0.9500 C(6)-H(6) 0.9500 C(7)-H(7A) 0.9900 C(7)-H(7B) 0.9900 C(8)-C(9) 1.384(4) C(8)-H(8) 0.9500 C(9)-C(10) 1.354(4) C(9)-H(9) 0.9500 C(10)-H(10) 0.9500 C(11)-C(16) 1.372(3) C(11)-C(12) 1.375(3) C(12)-C(13) 1.382(3) C(12)-H(12) 0.9500

223

Table E-3. Bond lengths [Å] and angles [°] for II-4 (continued) C(13)-C(14) 1.387(3) C(13)-H(13) 0.9500 C(14)-C(15) 1.383(3) C(14)-C(17) 1.513(3) C(15)-C(16) 1.388(3) C(15)-H(15) 0.9500 C(16)-H(16) 0.9500 C(17)-H(17A) 0.9900 C(17)-H(17B) 0.9900 C(18)-C(19) 1.387(4) C(18)-H(18) 0.9500 C(19)-C(20) 1.357(4) C(19)-H(19) 0.9500 C(20)-H(20) 0.9500 C(21)-C(22) 1.373(3) C(21)-C(26) 1.375(3) C(22)-C(23) 1.392(3) C(22)-H(22) 0.9500 C(23)-C(24) 1.386(3) C(23)-H(23) 0.9500 C(24)-C(25) 1.384(3) C(24)-C(27) 1.508(3) C(25)-C(26) 1.387(3) C(25)-H(25) 0.9500 C(26)-H(26) 0.9500 C(27)-H(27A) 0.9900 C(27)-H(27B) 0.9900 C(28)-C(29) 1.389(4) C(28)-H(28) 0.9500 C(29)-C(30) 1.371(4) C(29)-H(29) 0.9500 C(30)-H(30) 0.9500 C(31)-C(32) 1.373(3) C(31)-C(36) 1.377(3) C(32)-C(33) 1.389(3) C(32)-H(32) 0.9500 C(33)-C(34) 1.384(3) C(33)-H(33) 0.9500 C(34)-C(35) 1.392(3) C(34)-C(37) 1.514(3) C(35)-C(36) 1.382(3) C(35)-H(35) 0.9500

C(36)-H(36) 0.9500 C(37)-H(37A) 0.9900 C(37)-H(37B) 0.9900 C(38)-C(39) 1.391(4) C(38)-H(38) 0.9500 C(39)-C(40) 1.362(4) C(39)-H(39) 0.9500 C(40)-H(40) 0.9500 C(41)-C(42) 1.372(3) C(41)-C(46) 1.383(3) C(42)-C(43) 1.388(3) C(42)-H(42) 0.9500 C(43)-C(44) 1.383(3) C(43)-H(43) 0.9500 C(44)-C(45) 1.385(4) C(44)-C(47) 1.515(3) C(45)-C(46) 1.392(3) C(45)-H(45) 0.9500 C(46)-H(46) 0.9500 C(47)-H(47A) 0.9900 C(47)-H(47B) 0.9900 C(48)-C(49) 1.393(4) C(48)-H(48) 0.9500 C(49)-C(50) 1.359(4) C(49)-H(49) 0.9500 C(50)-H(50) 0.9500 C(51)-C(52) 1.382(3) C(51)-C(56) 1.383(3) C(52)-C(53) 1.390(3) C(52)-H(52) 0.9500 C(53)-C(54) 1.387(3) C(53)-H(53) 0.9500 C(54)-C(55) 1.389(4) C(54)-C(57) 1.516(3) C(55)-C(56) 1.387(3) C(55)-H(55) 0.9500 C(56)-H(56) 0.9500 C(57)-H(57A) 0.9900 C(57)-H(57B) 0.9900 C(58)-C(59) 1.371(4) C(58)-H(58) 0.9500 C(59)-C(60) 1.394(5) C(59)-H(59) 0.9500 C(60)-H(60) 0.9500

224

Table E-3. Bond lengths [Å] and angles [°] for II-4 (continued) N(1)-P(1)-O(1) 110.08(9) N(1)-P(1)-O(2) 107.55(10) O(1)-P(1)-O(2) 99.37(9) N(1)-P(1)-N(3) 117.66(10) O(1)-P(1)-N(3) 109.35(10) O(2)-P(1)-N(3) 111.27(9) N(1)-P(2)-O(4) 111.09(10) N(1)-P(2)-O(3) 110.39(9) O(4)-P(2)-O(3) 99.85(9) N(1)-P(2)-N(2) 117.78(10) O(4)-P(2)-N(2) 109.14(10) O(3)-P(2)-N(2) 107.01(9) N(2)-P(3)-N(3) 117.82(10) N(2)-P(3)-O(6) 106.74(10) N(3)-P(3)-O(6) 111.69(9) N(2)-P(3)-O(5) 110.52(9) N(3)-P(3)-O(5) 109.42(10) O(6)-P(3)-O(5) 99.01(8) C(1)-O(1)-P(1) 124.24(14) C(11)-O(2)-P(1) 122.85(14) C(21)-O(3)-P(2) 124.80(14) C(31)-O(4)-P(2) 117.90(14) C(41)-O(5)-P(3) 120.36(13) C(51)-O(6)-P(3) 125.80(15) P(1)-N(1)-P(2) 121.08(12) P(3)-N(2)-P(2) 122.16(12) P(3)-N(3)-P(1) 120.08(12) N(5)-N(4)-C(10) 112.0(2) N(5)-N(4)-C(7) 120.9(2) C(10)-N(4)-C(7) 126.9(2) C(8)-N(5)-N(4) 103.7(2) C(20)-N(6)-N(7) 111.4(2) C(20)-N(6)-C(17) 128.0(2) N(7)-N(6)-C(17) 120.6(2) C(18)-N(7)-N(6) 104.0(2) C(30)-N(8)-N(9) 112.2(2) C(30)-N(8)-C(27) 128.5(2) N(9)-N(8)-C(27) 119.3(2) C(28)-N(9)-N(8) 104.1(2) C(40)-N(10)-N(11) 112.1(2) C(40)-N(10)-C(37) 128.3(2) N(11)-N(10)-C(37) 119.6(2)

C(38)-N(11)-N(10) 103.8(2) C(50)-N(12)-N(13) 111.3(2) C(50)-N(12)-C(47) 127.8(2) N(13)-N(12)-C(47) 120.28(19) C(48)-N(13)-N(12) 104.52(19) C(58)-N(14)-N(15) 112.5(2) C(58)-N(14)-C(57) 128.7(2) N(15)-N(14)-C(57) 118.8(2) C(60)-N(15)-N(14) 104.3(3) C(6)-C(1)-C(2) 121.2(2) C(6)-C(1)-O(1) 115.87(19) C(2)-C(1)-O(1) 122.9(2) C(1)-C(2)-C(3) 118.8(2) C(1)-C(2)-H(2) 120.6 C(3)-C(2)-H(2) 120.6 C(4)-C(3)-C(2) 120.9(2) C(4)-C(3)-H(3) 119.6 C(2)-C(3)-H(3) 119.6 C(3)-C(4)-C(5) 119.1(2) C(3)-C(4)-C(7) 119.1(2) C(5)-C(4)-C(7) 121.8(2) C(6)-C(5)-C(4) 120.3(2) C(6)-C(5)-H(5) 119.8 C(4)-C(5)-H(5) 119.8 C(1)-C(6)-C(5) 119.7(2) C(1)-C(6)-H(6) 120.1 C(5)-C(6)-H(6) 120.1 N(4)-C(7)-C(4) 114.2(2) N(4)-C(7)-H(7A) 108.7 C(4)-C(7)-H(7A) 108.7 N(4)-C(7)-H(7B) 108.7 C(4)-C(7)-H(7B) 108.7 H(7A)-C(7)-H(7B) 107.6 N(5)-C(8)-C(9) 112.4(3) N(5)-C(8)-H(8) 123.8 C(9)-C(8)-H(8) 123.8 C(10)-C(9)-C(8) 104.7(3) C(10)-C(9)-H(9) 127.7 C(8)-C(9)-H(9) 127.7 N(4)-C(10)-C(9) 107.3(3) N(4)-C(10)-H(10) 126.3 C(9)-C(10)-H(10) 126.3 C(16)-C(11)-C(12) 121.8(2) C(16)-C(11)-O(2) 117.7(2) C(12)-C(11)-O(2) 120.4(2)

225

Table E-3. Bond lengths [Å] and angles [°] for II-4 (continued) C(11)-C(12)-C(13) 118.5(2) C(11)-C(12)-H(12) 120.8 C(13)-C(12)-H(12) 120.8 C(12)-C(13)-C(14) 121.4(2) C(12)-C(13)-H(13) 119.3 C(14)-C(13)-H(13) 119.3 C(15)-C(14)-C(13) 118.5(2) C(15)-C(14)-C(17) 122.4(2) C(13)-C(14)-C(17) 119.1(2) C(14)-C(15)-C(16) 120.9(2) C(14)-C(15)-H(15) 119.6 C(16)-C(15)-H(15) 119.6 C(11)-C(16)-C(15) 118.9(2) C(11)-C(16)-H(16) 120.6 C(15)-C(16)-H(16) 120.6 N(6)-C(17)-C(14) 113.8(2) N(6)-C(17)-H(17A) 108.8 C(14)-C(17)-H(17A) 108.8 N(6)-C(17)-H(17B) 108.8 C(14)-C(17)-H(17B) 108.8 H(17A)-C(17)-H(17B) 107.7 N(7)-C(18)-C(19) 112.1(3) N(7)-C(18)-H(18) 123.9 C(19)-C(18)-H(18) 123.9 C(20)-C(19)-C(18) 105.0(3) C(20)-C(19)-H(19) 127.5 C(18)-C(19)-H(19) 127.5 N(6)-C(20)-C(19) 107.5(2) N(6)-C(20)-H(20) 126.3 C(19)-C(20)-H(20) 126.3 C(22)-C(21)-C(26) 122.0(2) C(22)-C(21)-O(3) 121.5(2) C(26)-C(21)-O(3) 116.5(2) C(21)-C(22)-C(23) 118.5(2) C(21)-C(22)-H(22) 120.7 C(23)-C(22)-H(22) 120.7 C(24)-C(23)-C(22) 120.9(2) C(24)-C(23)-H(23) 119.6 C(22)-C(23)-H(23) 119.6 C(25)-C(24)-C(23) 119.0(2) C(25)-C(24)-C(27) 120.1(2) C(23)-C(24)-C(27) 121.0(2)

C(24)-C(25)-C(26) 120.8(2) C(24)-C(25)-H(25) 119.6 C(26)-C(25)-H(25) 119.6 C(21)-C(26)-C(25) 118.8(2) C(21)-C(26)-H(26) 120.6 C(25)-C(26)-H(26) 120.6 N(8)-C(27)-C(24) 111.8(2) N(8)-C(27)-H(27A) 109.2 C(24)-C(27)-H(27A) 109.2 N(8)-C(27)-H(27B) 109.2 C(24)-C(27)-H(27B) 109.2 H(27A)-C(27)-H(27B) 107.9 N(9)-C(28)-C(29) 111.9(2) N(9)-C(28)-H(28) 124.0 C(29)-C(28)-H(28) 124.0 C(30)-C(29)-C(28) 105.1(2) C(30)-C(29)-H(29) 127.5 C(28)-C(29)-H(29) 127.5 N(8)-C(30)-C(29) 106.7(2) N(8)-C(30)-H(30) 126.7 C(29)-C(30)-H(30) 126.7 C(32)-C(31)-C(36) 122.2(2) C(32)-C(31)-O(4) 118.8(2) C(36)-C(31)-O(4) 119.0(2) C(31)-C(32)-C(33) 118.2(2) C(31)-C(32)-H(32) 120.9 C(33)-C(32)-H(32) 120.9 C(34)-C(33)-C(32) 121.2(2) C(34)-C(33)-H(33) 119.4 C(32)-C(33)-H(33) 119.4 C(33)-C(34)-C(35) 118.9(2) C(33)-C(34)-C(37) 120.5(2) C(35)-C(34)-C(37) 120.6(2) C(36)-C(35)-C(34) 120.5(2) C(36)-C(35)-H(35) 119.7 C(34)-C(35)-H(35) 119.7 C(31)-C(36)-C(35) 118.9(2) C(31)-C(36)-H(36) 120.5 C(35)-C(36)-H(36) 120.5 N(10)-C(37)-C(34) 113.1(2) N(10)-C(37)-H(37A) 109.0 C(34)-C(37)-H(37A) 109.0 N(10)-C(37)-H(37B) 109.0 C(34)-C(37)-H(37B) 109.0 H(37A)-C(37)-H(37B) 107.8

226

Table E-3. Bond lengths [Å] and angles [°] for II-4 (continued) N(11)-C(38)-C(39) 112.0(2) N(11)-C(38)-H(38) 124.0 C(39)-C(38)-H(38) 124.0 C(40)-C(39)-C(38) 104.6(2) C(40)-C(39)-H(39) 127.7 C(38)-C(39)-H(39) 127.7 N(10)-C(40)-C(39) 107.4(2) N(10)-C(40)-H(40) 126.3 C(39)-C(40)-H(40) 126.3 C(42)-C(41)-C(46) 121.7(2) C(42)-C(41)-O(5) 118.1(2) C(46)-C(41)-O(5) 120.1(2) C(41)-C(42)-C(43) 119.0(2) C(41)-C(42)-H(42) 120.5 C(43)-C(42)-H(42) 120.5 C(44)-C(43)-C(42) 120.9(2) C(44)-C(43)-H(43) 119.5 C(42)-C(43)-H(43) 119.5 C(43)-C(44)-C(45) 118.9(2) C(43)-C(44)-C(47) 118.6(2) C(45)-C(44)-C(47) 122.3(2) C(44)-C(45)-C(46) 121.0(2) C(44)-C(45)-H(45) 119.5 C(46)-C(45)-H(45) 119.5 C(41)-C(46)-C(45) 118.4(2) C(41)-C(46)-H(46) 120.8 C(45)-C(46)-H(46) 120.8 N(12)-C(47)-C(44) 115.0(2) N(12)-C(47)-H(47A) 108.5 C(44)-C(47)-H(47A) 108.5 N(12)-C(47)-H(47B) 108.5 C(44)-C(47)-H(47B) 108.5 H(47A)-C(47)-H(47B) 107.5 N(13)-C(48)-C(49) 111.9(2) N(13)-C(48)-H(48) 124.0 C(49)-C(48)-H(48) 124.0

C(50)-C(49)-C(48) 104.6(2) C(50)-C(49)-H(49) 127.7 C(48)-C(49)-H(49) 127.7 N(12)-C(50)-C(49) 107.6(2) N(12)-C(50)-H(50) 126.2 C(49)-C(50)-H(50) 126.2 C(52)-C(51)-C(56) 121.0(2) C(52)-C(51)-O(6) 123.2(2) C(56)-C(51)-O(6) 115.7(2) C(51)-C(52)-C(53) 118.5(2) C(51)-C(52)-H(52) 120.7 C(53)-C(52)-H(52) 120.7 C(54)-C(53)-C(52) 121.8(2) C(54)-C(53)-H(53) 119.1 C(52)-C(53)-H(53) 119.1 C(53)-C(54)-C(55) 118.2(2) C(53)-C(54)-C(57) 120.2(2) C(55)-C(54)-C(57) 121.7(2) C(56)-C(55)-C(54) 121.0(2) C(56)-C(55)-H(55) 119.5 C(54)-C(55)-H(55) 119.5 C(51)-C(56)-C(55) 119.3(2) C(51)-C(56)-H(56) 120.3 C(55)-C(56)-H(56) 120.3 N(14)-C(57)-C(54) 113.4(2) N(14)-C(57)-H(57A) 108.9 C(54)-C(57)-H(57A) 108.9 N(14)-C(57)-H(57B) 108.9 C(54)-C(57)-H(57B) 108.9 H(57A)-C(57)-H(57B) 107.7 N(14)-C(58)-C(59) 106.4(3) N(14)-C(58)-H(58) 126.8 C(59)-C(58)-H(58) 126.8 C(58)-C(59)-C(60) 104.9(3) C(58)-C(59)-H(59) 127.6 C(60)-C(59)-H(59) 127.6 N(15)-C(60)-C(59) 111.9(3) N(15)-C(60)-H(60) 124.1 C(59)-C(60)-H(60) 124.1

227

Table E-4. Anisotropic displacement parameters (Å2x 103) for II-4. The anisotropic displacement factor exponent takes the form: -2π2[ h2 a*2U11 + ... + 2 h k a* b* U12 ] ________________________________________________________________________ U11 U22 U33 U23 U13 U12 ________________________________________________________________________ P(1) 24(1) 18(1) 18(1) 0(1) -2(1) 2(1) P(2) 24(1) 21(1) 18(1) 3(1) -2(1) 1(1) P(3) 26(1) 17(1) 18(1) 1(1) -4(1) 1(1) O(1) 23(1) 26(1) 20(1) -2(1) -3(1) 2(1) O(2) 35(1) 18(1) 19(1) 0(1) -1(1) 4(1) O(3) 26(1) 33(1) 18(1) 1(1) -2(1) 6(1) O(4) 30(1) 23(1) 22(1) 4(1) -3(1) -5(1) O(5) 30(1) 18(1) 22(1) 0(1) -5(1) 5(1) O(6) 30(1) 22(1) 19(1) 2(1) -4(1) -4(1) N(1) 27(1) 19(1) 19(1) 0(1) -4(1) 4(1) N(2) 25(1) 22(1) 20(1) 2(1) -4(1) -1(1) N(3) 26(1) 18(1) 20(1) 2(1) -4(1) -2(1) N(4) 38(1) 26(1) 25(1) -1(1) -6(1) -7(1) N(5) 50(2) 53(2) 35(1) 11(1) -9(1) -23(1) N(6) 39(1) 31(1) 21(1) 0(1) 3(1) 2(1) N(7) 45(1) 35(1) 33(1) 7(1) 1(1) 7(1) N(8) 33(1) 28(1) 19(1) 1(1) -4(1) -3(1) N(9) 37(1) 28(1) 32(1) 2(1) 0(1) -5(1) N(10) 30(1) 26(1) 27(1) -3(1) -4(1) -7(1) N(11) 34(1) 29(1) 34(1) 2(1) -4(1) -10(1) N(12) 32(1) 23(1) 27(1) -5(1) -5(1) 3(1) N(13) 29(1) 30(1) 29(1) -1(1) -5(1) 4(1) N(14) 39(1) 26(1) 23(1) 2(1) -1(1) -3(1) N(15) 50(2) 48(2) 30(1) -4(1) -6(1) -5(1) C(1) 24(1) 20(1) 19(1) 0(1) -1(1) -2(1) C(2) 25(1) 24(1) 25(1) 0(1) -4(1) 3(1) C(3) 28(1) 23(1) 26(1) 0(1) -2(1) 5(1) C(4) 28(1) 15(1) 24(1) 2(1) -2(1) -3(1) C(5) 26(1) 22(1) 32(1) -1(1) -9(1) -3(1) C(6) 21(1) 20(1) 31(1) -3(1) -2(1) -1(1) C(7) 35(2) 24(1) 29(1) -4(1) -7(1) 1(1) C(8) 64(2) 54(2) 43(2) 23(2) -20(2) -21(2) C(9) 50(2) 49(2) 42(2) 5(1) -22(1) -5(2) C(10) 35(2) 39(2) 31(1) -2(1) -9(1) -4(1) C(11) 26(1) 17(1) 18(1) -1(1) -1(1) 6(1) C(12) 24(1) 22(1) 28(1) -4(1) -6(1) 0(1) C(13) 24(1) 23(1) 34(1) 0(1) 4(1) -2(1) C(14) 30(1) 19(1) 22(1) -2(1) 2(1) 1(1) C(15) 29(1) 24(1) 23(1) -3(1) -5(1) 0(1)

228

Table E-4. Anisotropic displacement parameters (Å2x 103) for II-4 (continued) C(16) 26(1) 19(1) 26(1) -1(1) 1(1) -2(1) C(17) 49(2) 28(2) 26(1) -4(1) 7(1) -8(1) C(18) 39(2) 47(2) 32(1) 7(1) -6(1) -3(1) C(19) 39(2) 36(2) 27(1) -1(1) 1(1) -3(1) C(20) 35(2) 27(2) 26(1) 0(1) 3(1) 3(1) C(21) 22(1) 28(1) 16(1) 2(1) 1(1) 1(1) C(22) 34(1) 22(1) 26(1) -1(1) -6(1) -3(1) C(23) 36(1) 19(1) 26(1) 2(1) -4(1) 1(1) C(24) 25(1) 26(1) 19(1) 1(1) -1(1) -1(1) C(25) 42(2) 23(1) 25(1) -2(1) -2(1) -3(1) C(26) 39(2) 22(1) 24(1) 1(1) -1(1) 2(1) C(27) 31(1) 29(2) 24(1) 0(1) -2(1) 0(1) C(28) 37(2) 39(2) 27(1) 4(1) 3(1) 2(1) C(29) 45(2) 45(2) 22(1) -7(1) -5(1) 8(1) C(30) 41(2) 32(2) 29(1) -9(1) -13(1) 0(1) C(31) 29(1) 20(1) 22(1) 4(1) -2(1) -7(1) C(32) 28(1) 21(1) 28(1) 7(1) -7(1) -4(1) C(33) 29(1) 19(1) 34(1) 4(1) -5(1) -2(1) C(34) 29(1) 22(1) 26(1) 2(1) -1(1) -7(1) C(35) 28(1) 26(1) 28(1) 4(1) -9(1) -4(1) C(36) 25(1) 22(1) 31(1) 4(1) -3(1) -2(1) C(37) 35(2) 22(1) 33(1) 0(1) -2(1) -7(1) C(38) 38(2) 29(2) 30(1) 1(1) 1(1) -2(1) C(39) 37(2) 49(2) 26(1) -2(1) -6(1) 1(1) C(40) 30(1) 45(2) 30(1) -8(1) -4(1) -9(1) C(41) 26(1) 17(1) 23(1) 0(1) -8(1) 5(1) C(42) 29(1) 24(1) 26(1) 3(1) -1(1) 1(1) C(43) 30(1) 19(1) 34(1) -1(1) -8(1) -3(1) C(44) 31(1) 20(1) 26(1) -1(1) -7(1) 6(1) C(45) 28(1) 23(1) 26(1) 2(1) 0(1) 1(1) C(46) 27(1) 17(1) 30(1) 2(1) -5(1) 1(1) C(47) 41(2) 18(1) 30(1) -2(1) -7(1) 2(1) C(48) 38(2) 29(2) 29(1) 1(1) -5(1) -2(1) C(49) 43(2) 40(2) 32(1) 1(1) 9(1) -1(1) C(50) 32(2) 32(2) 42(2) -4(1) 3(1) 6(1) C(51) 27(1) 22(1) 17(1) 3(1) -4(1) 0(1) C(52) 35(1) 20(1) 23(1) -1(1) -8(1) -3(1) C(53) 31(1) 18(1) 30(1) 3(1) -4(1) -4(1) C(54) 30(1) 21(1) 25(1) 3(1) 0(1) 3(1) C(55) 30(1) 23(1) 22(1) -2(1) -3(1) 1(1) C(56) 27(1) 19(1) 25(1) 0(1) -4(1) -1(1) C(57) 34(1) 27(1) 26(1) 3(1) 2(1) -2(1) C(58) 48(2) 26(2) 35(2) 4(1) 12(1) 2(1)

229

Table E-4. Anisotropic displacement parameters (Å2x 103) for II-4 (continued) C(59) 45(2) 50(2) 40(2) 23(1) 14(1) 14(2) C(60) 44(2) 69(2) 30(2) 9(2) -4(1) 4(2) _______________________________________________________________________ Table E-5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for II-4. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ H(2) 4490 3503 5549 30 H(3) 4538 4148 6581 31 H(5) 8621 2822 6827 32 H(6) 8552 2166 5808 29 H(7A) 7182 4504 7361 35 H(7B) 5493 4184 7639 35 H(8) 7282 2297 9088 62 H(9) 10012 2711 8703 55 H(10) 9705 3732 7790 42 H(12) 8381 2211 3652 29 H(13) 9214 2427 2519 33 H(15) 5621 1181 2014 31 H(16) 4778 959 3149 29 H(17A) 7847 2572 1327 42 H(17B) 9257 1875 1351 42 H(18) 5343 1290 -162 47 H(19) 6572 -43 208 42 H(20) 8169 295 1117 36 H(22) 2230 599 6516 32 H(23) 3256 383 7539 33 H(25) 3150 2825 7818 36 H(26) 2110 3046 6803 35 H(27A) 4293 866 8486 34 H(27B) 4836 1784 8461 34 H(28) -380 1393 9892 42 H(29) 966 2579 10276 45 H(30) 3448 2680 9464 40 H(32) 3646 -250 4819 31 H(33) 4007 -961 3798 33 H(35) 172 323 3218 32 H(36) -192 1038 4233 31 H(37A) 3367 -1204 2720 36 H(37B) 1489 -1281 2792 36

230

Table E-5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for II-4 (continued) H(38) 3387 963 1229 39 H(39) 1093 293 854 45 H(40) 383 -771 1720 41 H(42) 3537 4972 4499 32 H(43) 3469 5787 5454 33 H(45) 35 4483 6413 31 H(46) 103 3654 5463 30 H(47A) 2626 6097 6571 35 H(47B) 749 6233 6561 35 H(48) 2494 4391 8392 38 H(49) 8 5271 8766 48 H(50) -658 6048 7750 43 H(52) 4003 3884 3281 31 H(53) 5160 4314 2233 32 H(55) 3129 2548 1328 30 H(56) 2035 2082 2372 28 H(57A) 5874 4118 1067 35 H(57B) 5368 3325 711 35 H(58) 4088 5509 917 46 H(59) 1969 5851 168 57 H(60) 1310 4508 -277 58


231

APPENDIX F SUPPLEMENTARY MATERIAL FOR THE X-RAY CRYSTAL STRUCTURE OF

C54H48N21O6P3 (II-5)

Table F-1. Crystal data and structure refinement for II-5.

Empirical formula C54H48N21O6P3 Formula weight 1180.04 Temperature 100(2) K Wavelength 0.71073 Å Crystal system Triclinic Space group P-1 Unit cell dimensions a = 8.694(3) Å α = 111.030(6)° b = 16.149(6) Å β = 98.615(6)° c = 20.924(7) Å γ = 96.147(6)° Volume 2669.7(16) Å3 Z 2 Density (calculated) 1.468 Mg/m3 Absorption coefficient 0.186 mm-1 F(000) 1224 Crystal size 0.27 x 0.16 x 0.04 mm3 Theta range for data collection 1.37 to 25.00°. Index ranges -9 ≤ h ≤ 10, -19 ≤ k ≤ 19, -24 ≤ l ≤ 24 Reflections collected 19200 Independent reflections 9375 [R(int) = 0.0580] Completeness to theta = 25.00° 99.5 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9926 and 0.9514 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 9375 / 0 / 757 Goodness-of-fit on F2 1.012 Final R indices [I>2sigma(I)] R1 = 0.0598, wR2 = 0.1195 R indices (all data) R1 = 0.0904, wR2 = 0.1312 Largest diff. peak and hole 0.355 and -0.413 e.Å-3

232

Table F-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-5. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ P(1) 7855(1) 3295(1) 701(1) 21(1) P(2) 4874(1) 2266(1) 273(1) 21(1) P(3) 7273(1) 1632(1) -387(1) 21(1) O(1) 8498(2) 4249(1) 689(1) 24(1) O(2) 8850(2) 3410(1) 1436(1) 24(1) O(3) 3214(2) 2427(1) -46(1) 23(1) O(4) 4310(2) 1847(1) 798(1) 23(1) O(5) 7397(2) 1582(1) -1146(1) 24(1) O(6) 8025(2) 781(1) -386(1) 23(1) N(1) 6021(3) 3208(2) 691(1) 21(1) N(2) 5493(3) 1520(2) -298(1) 21(1) N(3) 8433(3) 2517(2) 142(1) 20(1) N(4) 6856(3) 4337(2) -2386(1) 25(1) N(5) 5473(3) 3729(2) -2650(2) 30(1) N(6) 7290(3) 3286(2) -3321(2) 30(1) N(7) 9214(3) 6678(2) 4404(1) 31(1) N(8) 8159(4) 7191(2) 4278(2) 38(1) N(9) 10499(4) 8066(2) 4882(2) 46(1) N(10) 157(3) 1531(2) -3226(1) 25(1) N(11) 747(3) 747(2) -3363(2) 36(1) N(12) -1764(3) 480(2) -3968(2) 36(1) N(13) 4384(3) 4317(2) 4025(1) 26(1) N(14) 4692(4) 5117(2) 3939(2) 33(1) N(15) 2857(3) 5161(2) 4613(2) 33(1) N(16) 4132(3) -1003(2) -4290(1) 24(1) N(17) 4939(3) -1657(2) -4224(2) 32(1) N(18) 5097(3) -1480(2) -5241(2) 32(1) N(19) 10375(3) 1130(2) 2768(1) 27(1) N(20) 9283(3) 1651(2) 2979(2) 31(1) N(21) 11685(4) 2280(2) 3698(2) 37(1) C(1) 8087(4) 4405(2) 68(2) 23(1) C(2) 8709(4) 3981(2) -507(2) 24(1) C(3) 8353(4) 4193(2) -1090(2) 25(1) C(4) 7374(4) 4817(2) -1098(2) 24(1) C(5) 6765(4) 5231(2) -513(2) 27(1) C(6) 7115(4) 5032(2) 77(2) 27(1) C(7) 7072(4) 5094(2) -1720(2) 28(1) C(8) 5807(4) 3124(2) -3209(2) 30(1)

233

Table F-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-5 (continued) C(9) 7897(4) 4054(2) -2790(2) 28(1) C(10) 8741(4) 4008(2) 2101(2) 22(1) C(11) 7869(4) 4699(2) 2216(2) 26(1) C(12) 7866(4) 5253(2) 2902(2) 27(1) C(13) 8751(4) 5134(2) 3462(2) 27(1) C(14) 9606(4) 4432(2) 3326(2) 28(1) C(15) 9591(4) 3858(2) 2646(2) 26(1) C(16) 8734(5) 5712(2) 4212(2) 36(1) C(17) 8992(5) 8008(3) 4572(2) 42(1) C(18) 10591(4) 7216(3) 4762(2) 43(1) C(19) 2791(4) 2449(2) -713(2) 22(1) C(20) 1224(4) 2108(2) -1036(2) 24(1) C(21) 693(4) 2101(2) -1693(2) 25(1) C(22) 1713(4) 2425(2) -2037(2) 24(1) C(23) 3268(4) 2776(2) -1697(2) 27(1) C(24) 3824(4) 2791(2) -1033(2) 25(1) C(25) 1143(4) 2390(2) -2767(2) 29(1) C(26) -464(4) 148(2) -3810(2) 35(1) C(27) -1312(4) 1350(2) -3595(2) 33(1) C(28) 4570(4) 2321(2) 1524(2) 23(1) C(29) 3495(4) 2841(2) 1805(2) 25(1) C(30) 3719(4) 3274(2) 2527(2) 25(1) C(31) 5009(4) 3184(2) 2963(2) 22(1) C(32) 6055(4) 2654(2) 2663(2) 25(1) C(33) 5856(4) 2223(2) 1947(2) 25(1) C(34) 5273(4) 3598(2) 3750(2) 27(1) C(35) 3730(4) 5579(2) 4296(2) 33(1) C(36) 3309(4) 4364(2) 4423(2) 29(1) C(37) 6349(4) 1035(2) -1780(2) 23(1) C(38) 5622(4) 169(2) -1899(2) 27(1) C(39) 4628(4) -318(2) -2543(2) 27(1) C(40) 4384(4) 22(2) -3064(2) 25(1) C(41) 5157(4) 887(2) -2929(2) 28(1) C(42) 6130(4) 1395(2) -2286(2) 28(1) C(43) 3298(4) -529(2) -3757(2) 28(1) C(44) 5497(4) -1909(2) -4808(2) 33(1) C(45) 4233(4) -918(2) -4891(2) 27(1) C(46) 8472(4) 686(2) 262(2) 23(1) C(47) 7424(4) 181(2) 469(2) 24(1) C(48) 7900(4) 55(2) 1088(2) 26(1) C(49) 9405(4) 432(2) 1491(2) 25(1) C(50) 10430(4) 940(2) 1264(2) 28(1)

234

Table F-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-5 (continued) C(51) 9976(4) 1068(2) 652(2) 26(1) C(52) 9928(4) 284(2) 2155(2) 31(1) C(53) 10139(4) 2324(2) 3538(2) 33(1) C(54) 11777(4) 1513(2) 3197(2) 33(1) Table F-3. Bond lengths [Å] and angles [°] for II-5. P(1)-N(3) 1.567(3) P(1)-N(1) 1.581(3) P(1)-O(2) 1.585(2) P(1)-O(1) 1.591(2) P(2)-N(2) 1.571(3) P(2)-O(3) 1.586(2) P(2)-O(4) 1.590(2) P(2)-N(1) 1.592(3) P(3)-O(5) 1.581(2) P(3)-N(3) 1.583(3) P(3)-O(6) 1.584(2) P(3)-N(2) 1.585(3) O(1)-C(1) 1.412(4) O(2)-C(10) 1.405(4) O(3)-C(19) 1.403(4) O(4)-C(28) 1.404(4) O(5)-C(37) 1.412(4) O(6)-C(46) 1.420(4) N(4)-C(9) 1.335(4) N(4)-N(5) 1.369(4) N(4)-C(7) 1.456(4) N(5)-C(8) 1.321(4) N(6)-C(9) 1.322(4) N(6)-C(8) 1.360(4) N(7)-C(18) 1.338(4) N(7)-N(8) 1.358(4) N(7)-C(16) 1.460(4) N(8)-C(17) 1.313(5) N(9)-C(18) 1.318(5) N(9)-C(17) 1.350(5) N(10)-C(27) 1.332(4) N(10)-N(11) 1.368(4) N(10)-C(25) 1.457(4)

N(11)-C(26) 1.325(4) N(12)-C(27) 1.319(4) N(12)-C(26) 1.349(4) N(13)-C(36) 1.332(4) N(13)-N(14) 1.372(4) N(13)-C(34) 1.457(4) N(14)-C(35) 1.318(4) N(15)-C(36) 1.326(4) N(15)-C(35) 1.353(4) N(16)-C(45) 1.329(4) N(16)-N(17) 1.364(4) N(16)-C(43) 1.450(4) N(17)-C(44) 1.324(4) N(18)-C(45) 1.326(4) N(18)-C(44) 1.353(4) N(19)-C(54) 1.337(4) N(19)-N(20) 1.354(4) N(19)-C(52) 1.464(4) N(20)-C(53) 1.325(4) N(21)-C(54) 1.324(4) N(21)-C(53) 1.352(4) C(1)-C(2) 1.375(4) C(1)-C(6) 1.383(4) C(2)-C(3) 1.383(4) C(3)-C(4) 1.390(4) C(4)-C(5) 1.382(5) C(4)-C(7) 1.517(4) C(5)-C(6) 1.384(5) C(10)-C(15) 1.373(4) C(10)-C(11) 1.386(4) C(11)-C(12) 1.392(4) C(12)-C(13) 1.388(4) C(13)-C(14) 1.390(5)

235

Table F-3. Bond lengths [Å] and N(11)-C(26)-N(12) 115.8(3) angles [°] for II-5. N(12)-C(27)-N(10) 111.6(3)

C(33)-C(28)-C(29) 121.1(3) C(54)-N(21)-C(53) 101.4(3) C(33)-C(28)-O(4) 119.3(3) C(2)-C(1)-C(6) 121.9(3) C(29)-C(28)-O(4) 119.5(3) C(2)-C(1)-O(1) 120.5(3) C(28)-C(29)-C(30) 119.2(3) C(6)-C(1)-O(1) 117.5(3) C(29)-C(30)-C(31) 120.6(3) C(1)-C(2)-C(3) 118.7(3) C(32)-C(31)-C(30) 118.5(3) C(2)-C(3)-C(4) 120.7(3) C(32)-C(31)-C(34) 118.4(3) C(5)-C(4)-C(3) 119.3(3) C(30)-C(31)-C(34) 123.0(3) C(5)-C(4)-C(7) 120.0(3) C(31)-C(32)-C(33) 121.7(3) C(3)-C(4)-C(7) 120.5(3) C(28)-C(33)-C(32) 118.9(3) C(4)-C(5)-C(6) 120.9(3) N(13)-C(34)-C(31) 114.8(3) C(1)-C(6)-C(5) 118.5(3) N(14)-C(35)-N(15) 116.6(3) N(4)-C(7)-C(4) 112.7(3) N(15)-C(36)-N(13) 111.2(3) N(5)-C(8)-N(6) 115.9(3) C(42)-C(37)-C(38) 121.6(3) N(6)-C(9)-N(4) 111.6(3) C(42)-C(37)-O(5) 116.3(3) C(15)-C(10)-C(11) 121.6(3) C(38)-C(37)-O(5) 122.0(3) C(15)-C(10)-O(2) 114.2(3) C(39)-C(38)-C(37) 117.6(3) C(11)-C(10)-O(2) 124.2(3) C(40)-C(39)-C(38) 122.2(3) C(10)-C(11)-C(12) 118.8(3) C(39)-C(40)-C(41) 118.5(3) C(13)-C(12)-C(11) 120.8(3) C(39)-C(40)-C(43) 120.7(3) C(12)-C(13)-C(14) 118.7(3) C(41)-C(40)-C(43) 120.9(3) C(12)-C(13)-C(16) 121.8(3) C(42)-C(41)-C(40) 120.6(3) C(14)-C(13)-C(16) 119.4(3) C(37)-C(42)-C(41) 119.5(3) C(15)-C(14)-C(13) 121.2(3) N(16)-C(43)-C(40) 112.9(3) C(10)-C(15)-C(14) 118.8(3) N(17)-C(44)-N(18) 115.8(3) N(7)-C(16)-C(13) 114.9(3) N(18)-C(45)-N(16) 111.2(3) N(8)-C(17)-N(9) 115.3(4) C(47)-C(46)-C(51) 121.7(3) N(9)-C(18)-N(7) 111.1(4) C(47)-C(46)-O(6) 119.3(3) C(24)-C(19)-C(20) 121.1(3) C(51)-C(46)-O(6) 118.9(3) C(24)-C(19)-O(3) 123.9(3) C(46)-C(47)-C(48) 118.9(3) C(20)-C(19)-O(3) 115.0(3) C(49)-C(48)-C(47) 120.6(3) C(21)-C(20)-C(19) 119.4(3) C(48)-C(49)-C(50) 118.8(3) C(20)-C(21)-C(22) 120.9(3) C(48)-C(49)-C(52) 120.6(3) C(23)-C(22)-C(21) 118.5(3) C(50)-C(49)-C(52) 120.6(3) C(23)-C(22)-C(25) 120.5(3) C(51)-C(50)-C(49) 121.3(3) C(21)-C(22)-C(25) 121.0(3) C(50)-C(51)-C(46) 118.7(3) C(22)-C(23)-C(24) 121.3(3) N(19)-C(52)-C(49) 112.3(3) C(19)-C(24)-C(23) 118.7(3) N(20)-C(53)-N(21) 116.2(3) N(10)-C(25)-C(22) 112.5(3) N(21)-C(54)-N(19) 111.2(3)

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Table F-4. Anisotropic displacement parameters (Å2x 103) for II-5. The anisotropic displacement factor exponent takes the form: -2π2[ h2 a*2U11 + ... + 2 h k a* b* U12 ] ________________________________________________________________________ U11 U22 U33 U23 U13 U12 ________________________________________________________________________ P(1) 22(1) 14(1) 25(1) 8(1) 1(1) -3(1) P(2) 21(1) 15(1) 24(1) 9(1) 2(1) -2(1) P(3) 22(1) 14(1) 24(1) 7(1) 2(1) -2(1) O(1) 26(1) 14(1) 29(1) 10(1) 2(1) -7(1) O(2) 25(1) 19(1) 23(1) 6(1) 0(1) 2(1) O(3) 19(1) 24(1) 24(1) 9(1) 3(1) 1(1) O(4) 29(1) 18(1) 20(1) 9(1) 4(1) -6(1) O(5) 25(1) 18(1) 24(1) 5(1) 2(1) -7(1) O(6) 26(1) 15(1) 25(1) 6(1) 3(1) 2(1) N(1) 22(1) 13(1) 26(2) 7(1) 2(1) -2(1) N(2) 20(1) 12(1) 28(2) 8(1) 2(1) -6(1) N(3) 19(1) 15(1) 22(2) 5(1) 2(1) -2(1) N(4) 26(2) 20(2) 30(2) 14(1) 2(1) -1(1) N(5) 28(2) 23(2) 35(2) 13(1) -2(1) -5(1) N(6) 33(2) 22(2) 34(2) 14(1) 4(1) 3(1) N(7) 27(2) 31(2) 27(2) 5(1) 4(1) 0(1) N(8) 40(2) 27(2) 39(2) 7(2) 3(2) 3(2) N(9) 44(2) 38(2) 45(2) 8(2) 11(2) -9(2) N(10) 29(2) 21(2) 26(2) 10(1) 1(1) 6(1) N(11) 39(2) 26(2) 37(2) 6(2) -2(2) 12(2) N(12) 36(2) 31(2) 38(2) 14(2) -3(1) 2(1) N(13) 34(2) 17(2) 25(2) 8(1) 2(1) -2(1) N(14) 46(2) 20(2) 32(2) 14(1) 3(2) -2(1) N(15) 33(2) 29(2) 30(2) 8(1) -1(1) 3(1) N(16) 27(2) 18(2) 24(2) 7(1) 1(1) 1(1) N(17) 35(2) 24(2) 40(2) 15(2) 6(1) 10(1) N(18) 33(2) 27(2) 30(2) 9(1) 3(1) -1(1) N(19) 28(2) 20(2) 32(2) 12(1) -2(1) 1(1) N(20) 28(2) 22(2) 40(2) 10(1) 2(1) 3(1) N(21) 38(2) 28(2) 40(2) 13(2) -3(2) -1(1) C(1) 24(2) 16(2) 26(2) 9(2) 0(1) -7(1) C(2) 24(2) 15(2) 34(2) 10(2) 4(2) -1(1) C(3) 30(2) 15(2) 31(2) 10(2) 7(2) 1(1) C(4) 24(2) 14(2) 32(2) 10(2) 2(2) -5(1) C(5) 26(2) 16(2) 37(2) 10(2) 4(2) 2(1) C(6) 29(2) 16(2) 33(2) 7(2) 7(2) -1(2) C(7) 31(2) 17(2) 31(2) 8(2) 3(2) -2(2) C(8) 33(2) 22(2) 33(2) 13(2) 3(2) 1(2)

237

Table F-4. Anisotropic displacement parameters (Å2x 103) for II-5 (continued) C(9) 26(2) 27(2) 35(2) 17(2) 5(2) 1(2) C(10) 23(2) 16(2) 24(2) 6(2) 3(1) -5(1) C(11) 24(2) 23(2) 28(2) 8(2) 1(2) 0(2) C(12) 26(2) 22(2) 34(2) 11(2) 6(2) 1(2) C(13) 29(2) 22(2) 25(2) 8(2) 3(2) -5(2) C(14) 28(2) 25(2) 30(2) 13(2) 0(2) -5(2) C(15) 25(2) 20(2) 31(2) 10(2) 1(2) -3(2) C(16) 51(2) 24(2) 32(2) 10(2) 8(2) -2(2) C(17) 56(3) 30(2) 37(2) 9(2) 9(2) 2(2) C(18) 30(2) 47(3) 41(2) 6(2) 1(2) -1(2) C(19) 27(2) 14(2) 23(2) 8(1) 1(1) 2(1) C(20) 23(2) 20(2) 28(2) 10(2) 6(2) 0(1) C(21) 22(2) 21(2) 33(2) 13(2) 4(2) 0(1) C(22) 29(2) 15(2) 29(2) 10(2) 4(2) 4(1) C(23) 28(2) 21(2) 34(2) 14(2) 6(2) -1(2) C(24) 21(2) 21(2) 31(2) 9(2) 2(2) -3(1) C(25) 32(2) 20(2) 31(2) 11(2) 1(2) -1(2) C(26) 44(2) 23(2) 35(2) 11(2) 2(2) 8(2) C(27) 33(2) 30(2) 37(2) 16(2) 1(2) 8(2) C(28) 27(2) 16(2) 25(2) 9(2) 4(2) -4(1) C(29) 25(2) 19(2) 30(2) 12(2) 3(2) -2(1) C(30) 24(2) 20(2) 30(2) 10(2) 6(2) 0(1) C(31) 26(2) 13(2) 26(2) 8(2) 2(2) -3(1) C(32) 26(2) 19(2) 29(2) 14(2) -2(2) -2(1) C(33) 25(2) 17(2) 33(2) 11(2) 5(2) 2(1) C(34) 29(2) 21(2) 32(2) 12(2) 2(2) 1(2) C(35) 45(2) 26(2) 28(2) 12(2) 3(2) 7(2) C(36) 30(2) 25(2) 27(2) 9(2) 4(2) -5(2) C(37) 20(2) 23(2) 22(2) 6(2) 4(1) 2(1) C(38) 34(2) 17(2) 29(2) 10(2) 1(2) -1(2) C(39) 31(2) 15(2) 30(2) 7(2) 1(2) -6(2) C(40) 23(2) 21(2) 27(2) 6(2) 4(1) 0(1) C(41) 33(2) 23(2) 29(2) 13(2) 3(2) 3(2) C(42) 28(2) 19(2) 33(2) 11(2) 2(2) -3(2) C(43) 27(2) 25(2) 30(2) 10(2) 0(2) 2(2) C(44) 34(2) 26(2) 38(2) 11(2) 6(2) 7(2) C(45) 27(2) 21(2) 29(2) 9(2) 0(2) -5(2) C(46) 29(2) 14(2) 26(2) 6(2) 3(2) 5(1) C(47) 23(2) 12(2) 32(2) 5(2) 2(2) -1(1) C(48) 26(2) 15(2) 37(2) 11(2) 6(2) -1(1) C(49) 30(2) 13(2) 30(2) 8(2) 3(2) 5(1) C(50) 24(2) 17(2) 39(2) 11(2) -3(2) -6(1) C(51) 25(2) 14(2) 39(2) 11(2) 2(2) -3(1)

238

Table F-4. Anisotropic displacement parameters (Å2x 103) for II-5 (continued) C(52) 34(2) 17(2) 36(2) 9(2) -2(2) -1(2) C(53) 39(2) 27(2) 33(2) 12(2) 6(2) 4(2) C(54) 26(2) 24(2) 45(2) 12(2) 0(2) 0(2) ________________________________________________________________________ Table F-5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for II-5. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ H(2) 9370 3550 -503 29 H(3) 8783 3909 -1489 30 H(5) 6097 5659 -516 32 H(6) 6698 5319 479 32 H(7A) 6117 5377 -1708 33 H(7B) 7976 5549 -1682 33 H(8) 5057 2609 -3513 36 H(9) 8943 4365 -2706 34 H(11) 7283 4792 1834 31 H(12) 7251 5719 2987 33 H(14) 10211 4342 3705 34 H(15) 10160 3372 2559 32 H(16A) 7653 5602 4294 43 H(16B) 9446 5516 4525 43 H(17) 8564 8524 4566 51 H(18) 11513 7012 4910 52 H(20) 520 1882 -807 28 H(21) -385 1870 -1915 30 H(23) 3970 3011 -1921 32 H(24) 4895 3033 -804 30 H(25A) 532 2880 -2741 35 H(25B) 2069 2493 -2970 35 H(26) -419 -476 -4007 42 H(27) -1953 1792 -3591 39 H(29) 2612 2904 1509 29 H(30) 2984 3634 2724 30 H(32) 6935 2585 2956 29 H(33) 6593 1866 1749 30 H(34A) 4986 3118 3922 33 H(34B) 6412 3841 3939 33 H(35) 3653 6175 4330 40 H(36) 2917 3888 4553 34

239

Table F-5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for II-5 (continued) H(38) 5798 -80 -1552 33 H(39) 4097 -905 -2630 32 H(41) 5015 1129 -3281 34 H(42) 6642 1988 -2195 33 H(43A) 2520 -972 -3693 34 H(43B) 2708 -126 -3920 34 H(44) 6137 -2362 -4915 40 H(45) 3749 -508 -5050 32 H(47) 6393 -77 194 29 H(48) 7188 -293 1236 31 H(50) 11462 1203 1538 33 H(51) 10686 1413 501 32 H(52A) 9060 -105 2223 37 H(52B) 10842 -35 2110 37 H(53) 9691 2809 3811 40 H(54) 12718 1267 3149 40 ________________________________________________________________________ Symmetry transformations used to generate equivalent atoms:

240

APPENDIX G


C30H24N9O6P3 (II-7)

Table G-1. Crystal data and structure refinement for II-7.

Empirical formula C30H24N9O6P3 Formula weight 699.49 Temperature 100(2) K Wavelength 1.54178 Å Crystal system Orthorhombic Space group Pna2(1) Unit cell dimensions a = 24.9148(10) Å α = 90° b = 9.6737(4) Å β = 90° c = 12.7231(5) Å γ = 90° Volume 3066.5(2) Å3 Z 4 Density (calculated) 1.515 Mg/m3 Absorption coefficient 2.313 mm-1 F(000) 1440 Crystal size 0.34 x 0.12 x 0.07 mm3 Theta range for data collection 3.55 to 67.39°. Index ranges -29<=h<=29, -11<=k<=11, -14<=l<=10 Reflections collected 14252 Independent reflections 3811 [R(int) = 0.0258] Completeness to theta = 67.39° 96.2 % Absorption correction Numerical Max. and min. transmission 0.8511 and 0.5095 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 3811 / 1 / 433 Goodness-of-fit on F2 1.150 Final R indices [I>2sigma(I)] R1 = 0.0273, wR2 = 0.0727 R indices (all data) R1 = 0.0277, wR2 = 0.0730 Absolute structure parameter 0.010(13) Largest diff. peak and hole 0.340 and -0.244 e.Å-3

241

Table G-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-7. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ P(1) 6039(1) 8679(1) 814(1) 15(1) P(2) 6077(1) 6767(1) -779(1) 16(1) P(3) 6818(1) 8862(1) -724(1) 16(1) O(4) 6194(1) 8152(1) 1964(1) 20(1) O(6) 7428(1) 8513(1) -469(1) 20(1) O(2) 5680(1) 6648(1) -1746(1) 21(1) O(3) 5577(1) 9734(1) 1131(1) 19(1) N(7) 5177(1) 10033(2) -493(2) 24(1) O(5) 6911(1) 10042(1) -1573(1) 20(1) N(6) 6445(1) 10252(2) 2701(2) 24(1) O(1) 6191(1) 5151(1) -611(1) 21(1) C(1) 6522(1) 4661(2) 185(2) 19(1) N(4) 6803(1) 5568(2) 729(2) 19(1) N(3) 6517(1) 9477(2) 268(2) 17(1) N(5) 5061(1) 5322(2) -2572(2) 23(1) C(2) 6531(1) 3235(2) 321(2) 21(1) C(12) 5176(1) 11884(2) 766(2) 28(1) C(19) 7086(1) 10291(2) 4103(2) 32(1) C(20) 6747(1) 10925(2) 3413(2) 27(1) C(16) 6496(1) 8900(2) 2684(2) 19(1) N(1) 5801(1) 7373(2) 236(2) 18(1) C(5) 7127(1) 5049(2) 1477(2) 21(1) C(4) 7175(1) 3647(2) 1689(2) 23(1) N(2) 6578(1) 7531(2) -1258(2) 19(1) C(6) 5153(1) 6177(2) -1785(2) 19(1) C(10) 4549(1) 4918(2) -2698(2) 29(1) C(9) 4137(1) 5334(2) -2050(2) 32(1) C(8) 4252(1) 6229(3) -1238(3) 36(1) C(7) 4775(1) 6685(2) -1096(2) 28(1) C(3) 6871(1) 2732(2) 1092(2) 24(1) C(11) 5307(1) 10564(2) 422(2) 19(1) C(15) 4883(1) 10839(2) -1133(2) 30(1) C(14) 4720(1) 12158(2) -867(2) 34(1) C(13) 4873(1) 12684(2) 95(3) 37(1) C(18) 7120(1) 8856(2) 4069(2) 34(1) C(17) 6822(1) 8138(2) 3339(2) 24(1) N(8) 8067(1) 10200(2) -299(2) 30(1) C(21) 7758(1) 9308(2) 181(2) 18(1)

242

Table G-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-7 (continued) C(22) 7750(1) 9044(3) 1238(2) 30(1) C(25) 8411(1) 10891(3) 327(2) 35(1) C(24) 8446(1) 10723(3) 1385(2) 34(1) C(23) 8105(1) 9787(3) 1862(2) 37(1) C(26) 6500(1) 10548(2) -2219(2) 19(1) N(9) 6290(1) 11733(2) -1920(2) 29(1) C(29) 5750(1) 11657(3) -3478(2) 35(1) C(27) 6363(1) 9828(2) -3121(2) 29(1) C(30) 5918(1) 12274(3) -2566(2) 35(1) C(28) 5982(1) 10415(3) -3765(2) 35(1) Table G-3. Bond lengths [Å] and angles [°] for II-7. P(1)-N(1) 1.5775(17) P(1)-N(3) 1.5792(17) P(1)-O(3) 1.5901(14) P(1)-O(4) 1.5966(17) P(2)-N(2) 1.5726(17) P(2)-N(1) 1.5771(19) P(2)-O(2) 1.5818(17) P(2)-O(1) 1.6027(13) P(3)-N(2) 1.5745(18) P(3)-N(3) 1.5830(19) P(3)-O(5) 1.5889(16) P(3)-O(6) 1.5912(14) O(4)-C(16) 1.389(3) O(6)-C(21) 1.396(3) O(2)-C(6) 1.391(2) O(3)-C(11) 1.383(3) N(7)-C(11) 1.313(3) N(7)-C(15) 1.344(3) O(5)-C(26) 1.401(3) N(6)-C(16) 1.314(3) N(6)-C(20) 1.346(3) O(1)-C(1) 1.389(3) C(1)-N(4) 1.318(3) C(1)-C(2) 1.390(3) N(4)-C(5) 1.346(3) N(5)-C(6) 1.318(3) N(5)-C(10) 1.344(3) C(2)-C(3) 1.384(3)

C(2)-H(2) 0.9500 C(12)-C(13) 1.379(4) C(12)-C(11) 1.388(3) C(12)-H(12) 0.9500 C(19)-C(20) 1.364(4) C(19)-C(18) 1.391(3) C(19)-H(19) 0.9500 C(20)-H(20) 0.9500 C(16)-C(17) 1.377(3) C(5)-C(4) 1.389(3) C(5)-H(5) 0.9500 C(4)-C(3) 1.391(3) C(4)-H(4) 0.9500 C(6)-C(7) 1.377(3) C(10)-C(9) 1.377(4) C(10)-H(10) 0.9500 C(9)-C(8) 1.378(4) C(9)-H(9) 0.9500 C(8)-C(7) 1.390(3) C(8)-H(8) 0.9500 C(7)-H(7) 0.9500 C(3)-H(3) 0.9500 C(15)-C(14) 1.381(3) C(15)-H(15) 0.9500 C(14)-C(13) 1.378(4) C(14)-H(14) 0.9500

243

Table G-3. Bond lengths [Å] and angles [°] for II-7 (continued) C(13)-H(13) 0.9500 C(18)-C(17) 1.377(4) C(18)-H(18) 0.9500 C(17)-H(17) 0.9500 N(8)-C(21) 1.309(3) N(8)-C(25) 1.347(3) C(21)-C(22) 1.369(4) C(22)-C(23) 1.388(4) C(22)-H(22) 0.9500 C(25)-C(24) 1.358(4) C(25)-H(25) 0.9500 C(24)-C(23) 1.382(4) C(24)-H(24) 0.9500 C(23)-H(23) 0.9500 C(26)-N(9) 1.316(3) C(26)-C(27) 1.385(4) N(9)-C(30) 1.344(3) C(29)-C(30) 1.370(4) C(29)-C(28) 1.382(4) C(29)-H(29) 0.9500 C(27)-C(28) 1.377(4) C(27)-H(27) 0.9500 C(30)-H(30) 0.9500 C(28)-H(28) 0.9500 N(1)-P(1)-N(3) 118.03(10) N(1)-P(1)-O(3) 111.06(8) N(3)-P(1)-O(3) 110.09(8) N(1)-P(1)-O(4) 105.18(9) N(3)-P(1)-O(4) 112.17(9) O(3)-P(1)-O(4) 98.49(8) N(2)-P(2)-N(1) 119.20(9) N(2)-P(2)-O(2) 103.23(9) N(1)-P(2)-O(2) 113.08(8) N(2)-P(2)-O(1) 111.70(8) N(1)-P(2)-O(1) 109.27(9) O(2)-P(2)-O(1) 98.28(8) N(2)-P(3)-N(3) 118.08(9) N(2)-P(3)-O(5) 110.43(10) N(3)-P(3)-O(5) 109.98(8) N(2)-P(3)-O(6) 106.12(8) N(3)-P(3)-O(6) 111.75(9)

O(5)-P(3)-O(6) 98.70(8) C(16)-O(4)-P(1) 124.68(13) C(21)-O(6)-P(3) 124.40(13) C(6)-O(2)-P(2) 129.90(15) C(11)-O(3)-P(1) 124.03(14) C(11)-N(7)-C(15) 116.40(19) C(26)-O(5)-P(3) 122.86(13) C(16)-N(6)-C(20) 116.0(2) C(1)-O(1)-P(2) 122.40(13) N(4)-C(1)-O(1) 118.03(17) N(4)-C(1)-C(2) 125.9(2) O(1)-C(1)-C(2) 116.06(18) C(1)-N(4)-C(5) 116.16(18) P(1)-N(3)-P(3) 121.60(10) C(6)-N(5)-C(10) 116.0(2) C(3)-C(2)-C(1) 116.6(2) C(3)-C(2)-H(2) 121.7 C(1)-C(2)-H(2) 121.7 C(13)-C(12)-C(11) 116.7(2) C(13)-C(12)-H(12) 121.6 C(11)-C(12)-H(12) 121.6 C(20)-C(19)-C(18) 117.7(2) C(20)-C(19)-H(19) 121.1 C(18)-C(19)-H(19) 121.1 N(6)-C(20)-C(19) 124.2(2) N(6)-C(20)-H(20) 117.9 C(19)-C(20)-H(20) 117.9 N(6)-C(16)-C(17) 125.4(2) N(6)-C(16)-O(4) 118.50(19) C(17)-C(16)-O(4) 116.08(18) P(2)-N(1)-P(1) 121.03(10) N(4)-C(5)-C(4) 123.7(2) N(4)-C(5)-H(5) 118.2 C(4)-C(5)-H(5) 118.2 C(5)-C(4)-C(3) 117.9(2) C(5)-C(4)-H(4) 121.0 C(3)-C(4)-H(4) 121.0 P(2)-N(2)-P(3) 121.28(12) N(5)-C(6)-C(7) 126.0(2) N(5)-C(6)-O(2) 113.43(19) C(7)-C(6)-O(2) 120.38(19) N(5)-C(10)-C(9) 123.5(2) N(5)-C(10)-H(10) 118.3 C(9)-C(10)-H(10) 118.3 C(8)-C(9)-C(10) 118.5(2)

244

Table G-3. Bond lengths [Å] and angles [°] for II-7 (continued) C(8)-C(9)-H(9) 120.7 C(10)-C(9)-H(9) 120.7 C(9)-C(8)-C(7) 119.5(2) C(9)-C(8)-H(8) 120.3 C(7)-C(8)-H(8) 120.3 C(6)-C(7)-C(8) 116.5(2) C(6)-C(7)-H(7) 121.8 C(8)-C(7)-H(7) 121.8 C(2)-C(3)-C(4) 119.8(2) C(2)-C(3)-H(3) 120.1 C(4)-C(3)-H(3) 120.1 N(7)-C(11)-O(3) 118.14(17) N(7)-C(11)-C(12) 125.5(2) O(3)-C(11)-C(12) 116.3(2) N(7)-C(15)-C(14) 123.2(2) N(7)-C(15)-H(15) 118.4 C(14)-C(15)-H(15) 118.4 C(13)-C(14)-C(15) 118.5(2) C(13)-C(14)-H(14) 120.8 C(15)-C(14)-H(14) 120.8 C(12)-C(13)-C(14) 119.6(2) C(12)-C(13)-H(13) 120.2 C(14)-C(13)-H(13) 120.2 C(17)-C(18)-C(19) 119.5(2) C(17)-C(18)-H(18) 120.3 C(19)-C(18)-H(18) 120.3 C(16)-C(17)-C(18) 117.1(2) C(16)-C(17)-H(17) 121.4 C(18)-C(17)-H(17) 121.4 C(21)-N(8)-C(25) 115.2(2) N(8)-C(21)-C(22) 126.1(2) N(8)-C(21)-O(6) 115.6(2) C(22)-C(21)-O(6) 118.2(2) C(21)-C(22)-C(23) 117.1(2) C(21)-C(22)-H(22) 121.4 C(23)-C(22)-H(22) 121.4 N(8)-C(25)-C(24) 124.6(2) N(8)-C(25)-H(25) 117.7 C(24)-C(25)-H(25) 117.7 C(25)-C(24)-C(23) 118.3(2) C(25)-C(24)-H(24) 120.9 C(23)-C(24)-H(24) 120.9

C(24)-C(23)-C(22) 118.7(3) C(24)-C(23)-H(23) 120.7 C(22)-C(23)-H(23) 120.7 N(9)-C(26)-C(27) 125.4(2) N(9)-C(26)-O(5) 115.2(2) C(27)-C(26)-O(5) 119.35(19) C(26)-N(9)-C(30) 115.9(2) C(30)-C(29)-C(28) 118.4(2) C(30)-C(29)-H(29) 120.8 C(28)-C(29)-H(29) 120.8 C(28)-C(27)-C(26) 117.1(2) C(28)-C(27)-H(27) 121.4 C(26)-C(27)-H(27) 121.4 N(9)-C(30)-C(29) 123.9(2) N(9)-C(30)-H(30) 118.0 C(29)-C(30)-H(30) 118.0 C(27)-C(28)-C(29) 119.3(3) C(27)-C(28)-H(28) 120.4 C(29)-C(28)-H(28) 120.4

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Table G-4. Anisotropic displacement parameters (Å2x 103) for II-7. The anisotropic displacement factor exponent takes the form: -2π2[ h2 a*2U11 + ... + 2 h k a* b* U12 ] ________________________________________________________________________ U11 U22 U33 U23 U13 U12 ________________________________________________________________________ P(1) 16(1) 14(1) 14(1) 0(1) -1(1) 1(1) P(2) 17(1) 15(1) 17(1) -2(1) -2(1) -1(1) P(3) 15(1) 15(1) 17(1) -1(1) 0(1) 0(1) O(4) 26(1) 17(1) 17(1) 1(1) -4(1) -2(1) O(6) 18(1) 18(1) 23(1) -4(1) -1(1) -1(1) O(2) 18(1) 24(1) 20(1) -2(1) -2(1) -2(1) O(3) 20(1) 21(1) 16(1) -1(1) 0(1) 5(1) N(7) 28(1) 23(1) 19(1) 0(1) -2(1) 4(1) O(5) 18(1) 19(1) 22(1) 2(1) 0(1) -2(1) N(6) 29(1) 20(1) 23(1) 0(1) -3(1) -3(1) O(1) 24(1) 16(1) 22(1) -3(1) -5(1) -1(1) C(1) 18(1) 19(1) 19(1) 0(1) 1(1) 0(1) N(4) 18(1) 18(1) 22(1) -2(1) -1(1) -1(1) N(3) 18(1) 13(1) 21(1) -2(1) -4(1) 2(1) N(5) 29(1) 17(1) 22(1) 0(1) -5(1) -2(1) C(2) 24(1) 17(1) 22(1) -1(1) 1(1) -3(1) C(12) 28(1) 22(1) 34(2) -6(1) -1(1) 4(1) C(19) 39(1) 32(1) 26(2) 0(1) -7(1) -10(1) C(20) 35(1) 21(1) 25(1) -4(1) 1(1) -5(1) C(16) 19(1) 22(1) 15(1) -1(1) 0(1) -1(1) N(1) 16(1) 18(1) 19(1) 2(1) -1(1) -1(1) C(5) 19(1) 23(1) 20(1) -3(1) -1(1) -2(1) C(4) 23(1) 26(1) 20(1) 3(1) 1(1) 1(1) N(2) 19(1) 19(1) 18(1) -3(1) 0(1) 1(1) C(6) 18(1) 16(1) 23(1) 3(1) -6(1) 2(1) C(10) 37(1) 20(1) 31(2) 2(1) -14(1) -9(1) C(9) 21(1) 27(1) 47(2) 3(1) -13(1) -4(1) C(8) 19(1) 39(1) 49(2) -9(1) 1(1) 2(1) C(7) 22(1) 30(1) 33(2) -9(1) -3(1) 2(1) C(3) 31(1) 20(1) 23(1) 2(1) 2(1) 0(1) C(11) 15(1) 20(1) 21(1) 2(1) 0(1) 2(1) C(15) 31(1) 36(1) 23(1) 4(1) -3(1) 6(1) C(14) 30(1) 32(1) 39(2) 14(1) -2(1) 7(1) C(13) 36(1) 21(1) 54(2) 0(1) 0(1) 9(1) C(18) 36(1) 34(1) 31(2) 5(1) -10(1) -1(1) C(17) 28(1) 21(1) 24(1) 2(1) -4(1) 2(1) N(8) 28(1) 37(1) 24(1) 5(1) -2(1) -13(1) C(21) 15(1) 19(1) 20(1) -2(1) 0(1) 1(1)

246

Table G-4. Anisotropic displacement parameters (Å2x 103) for II-7 (continued) C(22) 27(1) 38(1) 25(2) 6(1) 0(1) -5(1) C(25) 32(1) 39(1) 32(2) 3(1) -6(1) -18(1) C(24) 30(1) 36(1) 36(2) -10(1) -10(1) -4(1) C(23) 34(1) 58(2) 21(2) -2(1) -5(1) -1(1) C(26) 16(1) 22(1) 20(1) 4(1) 2(1) -2(1) N(9) 32(1) 26(1) 28(1) 0(1) -2(1) 6(1) C(29) 26(1) 46(2) 31(2) 15(1) -5(1) 2(1) C(27) 26(1) 30(1) 30(2) -4(1) -2(1) -1(1) C(30) 35(1) 32(1) 37(2) 8(1) -2(1) 7(1) C(28) 32(1) 47(2) 27(2) 1(1) -8(1) -8(1) ______________________________________________________________________ Table G-5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for II-7. _______________________________________________________________________ x y z U(eq) _______________________________________________________________________ H(2) 6315 2638 -93 26 H(12) 5291 12219 1431 34 H(19) 7293 10812 4590 39 H(20) 6722 11905 3437 33 H(5) 7334 5677 1882 25 H(4) 7408 3322 2226 28 H(10) 4467 4314 -3264 35 H(9) 3781 5011 -2161 38 H(8) 3975 6533 -780 43 H(7) 4868 7313 -552 34 H(3) 6897 1765 1211 29 H(15) 4782 10484 -1800 36 H(14) 4507 12691 -1336 40 H(13) 4769 13592 294 44 H(18) 7346 8375 4546 41 H(17) 6841 7160 3289 29 H(22) 7513 8380 1533 36 H(25) 8645 11541 7 41 H(24) 8698 11235 1787 41 H(23) 8113 9656 2601 45 H(29) 5482 12073 -3903 41 H(27) 6526 8968 -3289 35 H(30) 5763 13136 -2379 42 H(28) 5878 9970 -4400 42 ________________________________________________________________________ Symmetry transformations used to generate equivalent atoms:

247

APPENDIX H


C30H24N9O6P3 (II-8)

Table H-1. Crystal data and structure refinement for II-8.

Empirical formula C30H24N9O6P3 Formula weight 699.49 Temperature 100(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group P2(1)/c Unit cell dimensions a = 17.9505(19) Å α = 90° b = 22.430(2) Å β = 90.587(2)° c = 7.5179(8) Å γ = 90° Volume 3026.8(6) Å3 Z 4 Density (calculated) 1.535 Mg/m3 Absorption coefficient 0.259 mm-1 F(000) 1440 Crystal size 0.33 x 0.17 x 0.16 mm3 Theta range for data collection 1.13 to 26.30°. Index ranges -22<=h<=22, -27<=k<=27, -9<=l<=9 Reflections collected 23971 Independent reflections 6145 [R(int) = 0.0475] Completeness to theta = 26.30° 100.0 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9597 and 0.8731 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 6145 / 0 / 433 Goodness-of-fit on F2 1.066 Final R indices [I>2sigma(I)] R1 = 0.0466, wR2 = 0.1123 R indices (all data) R1 = 0.0632, wR2 = 0.1176 Largest diff. peak and hole 0.412 and -0.346 e.Å-3

248

Table H-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-8. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ P(1) 3291(1) 5066(1) 1517(1) 19(1) P(2) 2540(1) 4900(1) 4679(1) 21(1) P(3) 1757(1) 5018(1) 1515(1) 19(1) O(1) 3781(1) 5623(1) 949(2) 23(1) O(2) 3775(1) 4553(1) 668(2) 24(1) O(3) 2458(1) 5358(1) 6260(2) 28(1) O(4) 2643(1) 4326(1) 5882(2) 29(1) O(5) 1217(1) 4559(1) 533(2) 22(1) O(6) 1328(1) 5619(1) 1111(2) 24(1) N(1) 1787(1) 4867(1) 3568(3) 21(1) N(2) 2521(1) 5063(1) 508(3) 21(1) N(3) 3279(1) 5022(1) 3613(3) 22(1) N(4) 2666(1) 6988(1) 1119(3) 30(1) N(5) 5166(1) 3427(1) 1573(3) 32(1) N(6) 4240(1) 3341(1) 6045(4) 44(1) N(7) 786(1) 6218(1) 7062(3) 33(1) N(8) 2172(1) 3146(1) -301(3) 30(1) C(28) -425(2) 5786(1) 3550(4) 29(1) C(1) 3550(1) 6203(1) 1427(3) 23(1) C(2) 4007(2) 6539(1) 2513(4) 28(1) C(3) 3771(2) 7111(1) 2914(4) 32(1) C(4) 3104(2) 7311(1) 2209(4) 30(1) C(5) 2903(1) 6438(1) 715(3) 26(1) C(6) 4423(1) 4309(1) 1423(3) 25(1) C(7) 4907(2) 4617(1) 2522(4) 30(1) C(8) 5522(2) 4313(1) 3171(4) 33(1) C(9) 5628(2) 3729(1) 2669(4) 33(1) C(10) 4570(2) 3722(1) 980(4) 28(1) C(11) 1958(1) 5837(1) 6179(3) 23(1) C(12) 2151(2) 6367(1) 5391(4) 32(1) C(13) 1642(2) 6825(1) 5459(4) 36(1) C(14) 976(2) 6738(1) 6303(4) 35(1) C(15) 1281(1) 5779(1) 6987(3) 27(1) C(16) 3110(1) 3852(1) 5413(3) 24(1) C(17) 2907(2) 3442(1) 4143(4) 28(1) C(18) 3391(2) 2975(1) 3845(4) 35(1) C(19) 4045(2) 2941(1) 4809(4) 38(1)

249

Table H-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-8 (continued) C(20) 3774(2) 3794(1) 6322(4) 34(1) C(21) 1393(1) 3949(1) 615(3) 22(1) C(22) 945(1) 3575(1) 1590(3) 26(1) C(23) 1125(1) 2977(1) 1609(4) 28(1) C(24) 1740(2) 2787(1) 678(4) 30(1) C(25) 1990(1) 3726(1) -321(3) 26(1) C(26) 688(1) 5838(1) 1918(3) 22(1) C(27) 578(2) 6448(1) 1738(4) 27(1) N(9) -6(1) 6730(1) 2428(3) 32(1) C(29) -493(2) 6394(1) 3329(4) 30(1) C(30) 183(1) 5493(1) 2817(3) 26(1) Table H-3. Bond lengths [Å] and angles [°] for II-8. P(1)-N(2) 1.571(2) P(1)-N(3) 1.579(2) P(1)-O(2) 1.5802(17) P(1)-O(1) 1.5885(17) P(2)-O(3) 1.5789(18) P(2)-N(3) 1.581(2) P(2)-N(1) 1.582(2) P(2)-O(4) 1.5843(18) P(3)-N(2) 1.576(2) P(3)-N(1) 1.581(2) P(3)-O(6) 1.5809(17) P(3)-O(5) 1.5900(17) O(1)-C(1) 1.413(3) O(2)-C(6) 1.401(3) O(3)-C(11) 1.401(3) O(4)-C(16) 1.401(3) O(5)-C(21) 1.406(3) O(6)-C(26) 1.395(3) N(4)-C(5) 1.341(3) N(4)-C(4) 1.343(3) N(5)-C(10) 1.331(3) N(5)-C(9) 1.346(4) N(6)-C(19) 1.335(4) N(6)-C(20) 1.335(4) N(7)-C(15) 1.328(3) N(7)-C(14) 1.344(4) N(8)-C(25) 1.341(3)

N(8)-C(24) 1.343(3) C(28)-C(29) 1.379(4) C(28)-C(30) 1.391(4) C(1)-C(2) 1.376(4) C(1)-C(5) 1.379(4) C(2)-C(3) 1.386(4) C(3)-C(4) 1.379(4) C(6)-C(7) 1.378(4) C(6)-C(10) 1.383(4) C(7)-C(8) 1.382(4) C(8)-C(9) 1.378(4) C(11)-C(15) 1.370(4) C(11)-C(12) 1.374(4) C(12)-C(13) 1.376(4) C(13)-C(14) 1.373(4) C(16)-C(17) 1.372(4) C(16)-C(20) 1.374(4) C(17)-C(18) 1.380(4) C(18)-C(19) 1.375(4) C(21)-C(22) 1.378(4) C(21)-C(25) 1.381(4) C(22)-C(23) 1.380(4) C(23)-C(24) 1.381(4) C(26)-C(30) 1.374(4) C(26)-C(27) 1.387(3) C(27)-N(9) 1.334(3) N(9)-C(29) 1.343(4)

250

Table H-3. Bond lengths [Å] and angles [°] for II-8 (continued) N(2)-P(1)-N(3) 117.39(11) N(2)-P(1)-O(2) 106.72(10) N(3)-P(1)-O(2) 111.80(10) N(2)-P(1)-O(1) 111.09(10) N(3)-P(1)-O(1) 109.28(10) O(2)-P(1)-O(1) 99.00(9) O(3)-P(2)-N(3) 110.72(11) O(3)-P(2)-N(1) 110.10(10) N(3)-P(2)-N(1) 117.17(11) O(3)-P(2)-O(4) 96.36(10) N(3)-P(2)-O(4) 109.65(10) N(1)-P(2)-O(4) 110.89(11) N(2)-P(3)-N(1) 117.46(11) N(2)-P(3)-O(6) 106.04(10) N(1)-P(3)-O(6) 112.49(10) N(2)-P(3)-O(5) 110.42(10) N(1)-P(3)-O(5) 109.21(10) O(6)-P(3)-O(5) 99.76(9) C(1)-O(1)-P(1) 119.44(15) C(6)-O(2)-P(1) 125.37(16) C(11)-O(3)-P(2) 122.01(15) C(16)-O(4)-P(2) 122.70(15) C(21)-O(5)-P(3) 118.22(14) C(26)-O(6)-P(3) 128.22(16) P(3)-N(1)-P(2) 121.75(13) P(1)-N(2)-P(3) 122.32(13) P(1)-N(3)-P(2) 122.49(13) C(5)-N(4)-C(4) 116.7(2) C(10)-N(5)-C(9) 116.4(2) C(19)-N(6)-C(20) 117.3(3) C(15)-N(7)-C(14) 116.9(2) C(25)-N(8)-C(24) 116.5(2) C(29)-C(28)-C(30) 119.2(3) C(2)-C(1)-C(5) 121.0(2) C(2)-C(1)-O(1) 118.7(2)

C(5)-C(1)-O(1) 120.1(2) C(1)-C(2)-C(3) 117.0(3) C(4)-C(3)-C(2) 118.9(3) N(4)-C(4)-C(3) 124.1(3) N(4)-C(5)-C(1) 122.1(2) C(7)-C(6)-C(10) 120.1(2) C(7)-C(6)-O(2) 124.3(2) C(10)-C(6)-O(2) 115.7(2) C(6)-C(7)-C(8) 117.5(3) C(9)-C(8)-C(7) 119.0(3) N(5)-C(9)-C(8) 124.0(3) N(5)-C(10)-C(6) 123.1(3) C(15)-C(11)-C(12) 120.2(2) C(15)-C(11)-O(3) 118.6(2) C(12)-C(11)-O(3) 121.2(2) C(11)-C(12)-C(13) 117.3(3) C(14)-C(13)-C(12) 119.5(3) N(7)-C(14)-C(13) 123.1(3) N(7)-C(15)-C(11) 123.1(3) C(17)-C(16)-C(20) 120.4(2) C(17)-C(16)-O(4) 121.9(2) C(20)-C(16)-O(4) 117.7(2) C(16)-C(17)-C(18) 117.3(3) C(19)-C(18)-C(17) 119.4(3) N(6)-C(19)-C(18) 123.2(3) N(6)-C(20)-C(16) 122.5(3) C(22)-C(21)-C(25) 120.7(2) C(22)-C(21)-O(5) 118.9(2) C(25)-C(21)-O(5) 120.4(2) C(21)-C(22)-C(23) 117.3(2) C(22)-C(23)-C(24) 118.8(2) N(8)-C(24)-C(23) 124.2(2) N(8)-C(25)-C(21) 122.4(2) C(30)-C(26)-C(27) 120.6(2) C(30)-C(26)-O(6) 124.5(2) C(27)-C(26)-O(6) 114.9(2) N(9)-C(27)-C(26) 122.8(2) C(27)-N(9)-C(29) 116.6(2)

N(9)-C(29)-C(28) 124.0(2) C(26)-C(30)-C(28) 116.9(2)

251

Table H-4. Anisotropic displacement parameters (Å2x 103) for II-8. The anisotropic displacement factor exponent takes the form: -2π2[ h2 a*2U11 + ... + 2 h k a* b* U12 ] ________________________________________________________________________ U11 U22 U33 U23 U13 U12 ________________________________________________________________________ P(1) 19(1) 19(1) 20(1) 0(1) 2(1) 2(1) P(2) 23(1) 22(1) 18(1) 1(1) 2(1) 2(1) P(3) 20(1) 17(1) 20(1) 1(1) 1(1) 1(1) O(1) 22(1) 22(1) 26(1) 1(1) 5(1) 0(1) O(2) 23(1) 24(1) 25(1) -4(1) 0(1) 6(1) O(3) 28(1) 34(1) 22(1) -6(1) -3(1) 8(1) O(4) 34(1) 30(1) 23(1) 8(1) 7(1) 8(1) O(5) 20(1) 19(1) 25(1) 0(1) -2(1) 1(1) O(6) 25(1) 19(1) 27(1) 2(1) 5(1) 4(1) N(1) 22(1) 20(1) 21(1) 1(1) 4(1) -2(1) N(2) 23(1) 21(1) 18(1) 0(1) 1(1) 1(1) N(3) 21(1) 24(1) 20(1) 1(1) 0(1) 0(1) N(4) 37(1) 22(1) 31(1) 5(1) 0(1) -1(1) N(5) 32(1) 32(1) 32(1) 5(1) 5(1) 9(1) N(6) 32(1) 36(2) 63(2) 8(1) -11(1) 5(1) N(7) 27(1) 40(1) 33(1) -8(1) 3(1) 3(1) N(8) 33(1) 23(1) 35(1) -5(1) 7(1) 0(1) C(28) 23(1) 34(2) 29(1) 0(1) 1(1) 2(1) C(1) 27(1) 20(1) 22(1) 3(1) 7(1) -1(1) C(2) 26(1) 29(2) 29(1) 1(1) 2(1) -5(1) C(3) 39(2) 29(2) 27(1) 0(1) 3(1) -11(1) C(4) 41(2) 20(1) 30(2) 3(1) 5(1) -3(1) C(5) 27(1) 24(1) 26(1) 2(1) 0(1) -4(1) C(6) 22(1) 29(1) 24(1) 2(1) 5(1) 6(1) C(7) 28(1) 31(2) 31(2) -5(1) 2(1) 1(1) C(8) 24(1) 45(2) 29(2) -2(1) 0(1) 2(1) C(9) 29(2) 42(2) 29(2) 8(1) 6(1) 11(1) C(10) 30(1) 26(1) 27(1) 1(1) 4(1) 3(1) C(11) 21(1) 26(1) 21(1) -5(1) -1(1) 1(1) C(12) 25(1) 36(2) 34(2) -4(1) 2(1) -5(1) C(13) 39(2) 23(1) 47(2) -1(1) -1(1) -4(1) C(14) 35(2) 32(2) 39(2) -11(1) -5(1) 7(1) C(15) 26(1) 29(1) 25(1) -3(1) 2(1) -3(1) C(16) 23(1) 23(1) 25(1) 7(1) 4(1) 1(1) C(17) 26(1) 27(1) 31(2) 6(1) -3(1) -5(1) C(18) 41(2) 26(2) 39(2) -1(1) 7(1) -5(1) C(19) 33(2) 26(2) 56(2) 7(1) 12(1) 4(1) C(20) 34(2) 29(2) 39(2) 2(1) -9(1) 0(1)

252

Table H-4. Anisotropic displacement parameters (Å2x 103) for II-8 (continued) C(21) 22(1) 21(1) 24(1) -4(1) -4(1) -1(1) C(22) 19(1) 29(1) 30(1) -3(1) 3(1) -3(1) C(23) 26(1) 24(1) 34(2) 0(1) 4(1) -5(1) C(24) 34(2) 20(1) 35(2) -4(1) 1(1) 1(1) C(25) 29(1) 26(1) 24(1) -2(1) 4(1) -4(1) C(26) 22(1) 22(1) 23(1) -1(1) -2(1) 4(1) C(27) 29(1) 23(1) 30(1) 1(1) 2(1) 3(1) N(9) 34(1) 28(1) 33(1) -4(1) 2(1) 8(1) C(29) 26(1) 36(2) 29(1) -5(1) -1(1) 9(1) C(30) 26(1) 22(1) 29(1) 0(1) 0(1) 2(1) Table H-5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for II-8. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ H(28) -788 5569 4194 34 H(2) 4464 6385 2967 34 H(3) 4063 7361 3663 38 H(4) 2945 7701 2513 36 H(5) 2616 6202 -88 31 H(7) 4822 5022 2821 36 H(8) 5866 4504 3952 39 H(9) 6054 3526 3124 40 H(10) 4228 3520 217 33 H(12) 2617 6416 4823 38 H(13) 1750 7199 4926 43 H(14) 634 7060 6353 42 H(15) 1161 5408 7519 32 H(17) 2452 3478 3494 34 H(18) 3273 2679 2982 42 H(19) 4373 2618 4584 46 H(20) 3906 4088 7180 41 H(22) 529 3724 2224 31 H(23) 830 2701 2251 34 H(24) 1866 2376 733 36 H(25) 2282 3993 -1005 31 H(27) 933 6673 1095 33 H(29) -909 6586 3847 36 H(30) 246 5075 2932 31 ________________________________________________________________________ Symmetry transformations used to generate equivalent atoms:

253

APPENDIX I


C30H24N9O6P3 (II-9)

Table I-1. Crystal data and structure refinement for II-9.

Empirical formula C30H24N9O6P3 Formula weight 699.49 Temperature 100(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group C2/c Unit cell dimensions a = 14.037(8) Å α = 90° b = 10.968(7) Å β = 91.293(10)° c = 19.633(12) Å γ = 90° Volume 3022(3) Å3 Z 4 Density (calculated) 1.538 Mg/m3 Absorption coefficient 0.260 mm-1 F(000) 1440 Crystal size 0.48 x 0.45 x 0.19 mm3 Theta range for data collection 2.08 to 26.29°. Index ranges -17 ≤ h ≤ 17, -13 ≤ k ≤ 13, -24 ≤ l ≤ 24 Reflections collected 11417 Independent reflections 3050 [R(int) = 0.0621] Completeness to theta = 26.29° 99.6 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9523 and 0.8855 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 3050 / 0 / 218 Goodness-of-fit on F2 0.979 Final R indices [I>2sigma(I)] R1 = 0.0470, wR2 = 0.1209 R indices (all data) R1 = 0.0578, wR2 = 0.1237 Largest diff. peak and hole 0.705 and -0.390 e.Å-3

254

Table I-2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for II-9. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ P(1) 0 3460(1) 2500 16(1) P(2) 592(1) 1267(1) 3069(1) 18(1) O(1) 592(1) 4443(1) 2101(1) 20(1) O(2) 1642(1) 717(2) 3141(1) 23(1) O(3) 180(1) 849(2) 3776(1) 24(1) N(1) 654(1) 2699(2) 3013(1) 19(1) N(2) 0 564(2) 2500 21(1) N(3) 1854(2) 4098(2) 209(1) 27(1) N(4) 3687(2) 1520(2) 1700(1) 34(1) N(5) 971(2) 1841(2) 5757(1) 37(1) C(1) 998(2) 4269(2) 1467(1) 18(1) C(2) 710(2) 5038(2) 943(1) 25(1) C(3) 1166(2) 4914(2) 330(1) 28(1) C(4) 2111(2) 3384(2) 732(1) 28(1) C(5) 1710(2) 3431(2) 1373(1) 24(1) C(6) 2321(2) 992(2) 2648(1) 22(1) C(7) 2306(2) 383(2) 2030(1) 26(1) C(8) 3012(2) 689(3) 1576(1) 32(1) C(9) 3679(2) 2072(3) 2307(1) 32(1) C(10) 3010(2) 1839(2) 2801(1) 26(1) C(11) 483(2) 1224(2) 4419(1) 26(1) C(12) 1427(2) 1217(3) 4638(1) 38(1) C(13) 1610(2) 1511(3) 5309(1) 41(1) C(14) 67(2) 1853(2) 5537(1) 32(1) C(15) -214(2) 1544(2) 4869(1) 31(1) Table I-3. Bond lengths [Å] and angles [°] for II-9. P(1)-O(1)#1 1.5803(17) P(1)-O(1) 1.5803(17) P(1)-N(1)#1 1.584(2) P(1)-N(1) 1.584(2) P(2)-N(1) 1.578(2) P(2)-N(2) 1.5783(16) P(2)-O(3) 1.5817(18) P(2)-O(2) 1.5956(18)

O(1)-C(1) 1.394(3) O(2)-C(6) 1.407(3) O(3)-C(11) 1.386(3) N(2)-P(2)#1 1.5783(16) N(3)-C(4) 1.334(3) N(3)-C(3) 1.343(3) N(4)-C(8) 1.334(4) N(4)-C(9) 1.336(4)

255

Table I-3. Bond lengths [Å] and angles [°] for II-9 (continued) N(5)-C(13) 1.321(3) N(5)-C(14) 1.331(4) C(1)-C(5) 1.373(3) C(1)-C(2) 1.384(3) C(2)-C(3) 1.382(3) C(4)-C(5) 1.392(3) C(6)-C(10) 1.369(4) C(6)-C(7) 1.385(3) C(7)-C(8) 1.388(3) C(9)-C(10) 1.390(3) C(11)-C(15) 1.379(4) C(11)-C(12) 1.384(4) C(12)-C(13) 1.375(4) C(14)-C(15) 1.403(4) O(1)#1-P(1)-O(1) 93.93(13) O(1)#1-P(1)-N(1)#1 111.75(10) O(1)-P(1)-N(1)#1 110.36(10) O(1)#1-P(1)-N(1) 110.36(10) O(1)-P(1)-N(1) 111.75(10) N(1)#1-P(1)-N(1) 116.47(16) N(1)-P(2)-N(2) 117.73(12) N(1)-P(2)-O(3) 111.81(10) N(2)-P(2)-O(3) 106.41(9) N(1)-P(2)-O(2) 109.28(10) N(2)-P(2)-O(2) 110.40(10) O(3)-P(2)-O(2) 99.69(9) C(1)-O(1)-P(1) 125.38(15) C(6)-O(2)-P(2) 119.82(15) C(11)-O(3)-P(2) 127.00(16) P(2)-N(1)-P(1) 122.47(13) P(2)-N(2)-P(2)#1 121.58(18) C(4)-N(3)-C(3) 115.9(2) C(8)-N(4)-C(9) 116.9(2) C(13)-N(5)-C(14) 116.4(3) C(5)-C(1)-C(2) 120.7(2) C(5)-C(1)-O(1) 121.6(2) C(2)-C(1)-O(1) 117.5(2) C(3)-C(2)-C(1) 117.0(2) N(3)-C(3)-C(2) 124.7(2) N(3)-C(4)-C(5) 124.6(2) C(1)-C(5)-C(4) 117.1(2)

C(10)-C(6)-C(7) 121.1(2) C(10)-C(6)-O(2) 118.7(2) C(7)-C(6)-O(2) 120.2(2) C(6)-C(7)-C(8) 116.7(2) N(4)-C(8)-C(7) 124.2(3) N(4)-C(9)-C(10) 124.0(3) C(6)-C(10)-C(9) 117.1(2) C(15)-C(11)-C(12) 119.4(3) C(15)-C(11)-O(3) 116.8(2) C(12)-C(11)-O(3) 123.6(2) C(13)-C(12)-C(11) 117.0(3) N(5)-C(13)-C(12) 125.9(3) N(5)-C(14)-C(15) 123.2(3) C(11)-C(15)-C(14) 118.1(3)

256

Table I-4. Anisotropic displacement parameters (Å2x 103) for II-9. The anisotropic displacement factor exponent takes the form: -2π2[ h2 a*2U11 + ... + 2 h k a* b* U12 ] ________________________________________________________________________ U11 U22 U33 U23 U13 U12 ________________________________________________________________________ P(1) 11(1) 20(1) 16(1) 0 7(1) 0 P(2) 14(1) 24(1) 17(1) 2(1) 7(1) 2(1) O(1) 17(1) 24(1) 19(1) -2(1) 10(1) -4(1) O(2) 15(1) 32(1) 21(1) 6(1) 10(1) 8(1) O(3) 19(1) 35(1) 18(1) 4(1) 7(1) 0(1) N(1) 13(1) 25(1) 19(1) -1(1) 5(1) 1(1) N(2) 20(2) 19(2) 22(2) 0 6(1) 0 N(3) 26(1) 34(1) 22(1) -2(1) 9(1) -4(1) N(4) 22(1) 42(2) 38(2) 11(1) 15(1) 9(1) N(5) 41(2) 36(1) 34(1) -4(1) 8(1) -3(1) C(1) 13(1) 23(1) 18(1) -3(1) 7(1) -5(1) C(2) 17(1) 34(2) 25(1) 4(1) 7(1) 3(1) C(3) 25(1) 39(2) 21(1) 6(1) 5(1) 2(1) C(4) 25(1) 30(2) 29(2) -2(1) 14(1) 2(1) C(5) 22(1) 26(1) 24(1) 4(1) 10(1) 2(1) C(6) 16(1) 28(1) 22(1) 6(1) 10(1) 8(1) C(7) 25(1) 29(2) 23(1) 1(1) 8(1) 5(1) C(8) 36(2) 37(2) 24(1) 2(1) 14(1) 14(1) C(9) 14(1) 40(2) 40(2) 5(1) 6(1) 4(1) C(10) 17(1) 36(2) 25(1) 2(1) 2(1) 6(1) C(11) 28(1) 26(1) 24(1) 3(1) 9(1) 1(1) C(12) 26(2) 60(2) 27(2) 3(1) 6(1) 9(1) C(13) 30(2) 67(2) 26(2) 6(1) 2(1) 9(2) C(14) 33(2) 33(2) 32(2) -1(1) 13(1) 1(1) C(15) 27(2) 34(2) 33(2) -1(1) 12(1) 1(1) ________________________________________________________________________ Table I-5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for II-9. ________________________________________________________________________ x y z U(eq) ________________________________________________________________________ H(2) 220 5624 1002 30 H(3) 979 5445 -31 34 H(4) 2601 2803 661 34 H(5) 1921 2907 1731 29

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Table I-5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for II-9 (continued). H(7) 1837 -214 1921 31 H(8) 3014 280 1149 39 H(9) 4159 2660 2406 38 H(10) 3029 2249 3228 31 H(12) 1926 1019 4339 45 H(13) 2255 1474 5465 49 H(14) -411 2081 5847 39 H(15) -867 1555 4730 37 _______________________________________________________________________


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APPENDIX J

ABBREVIATIONS AND ACRONYMS

σ sigma (electric current)

µm micrometer

ΔG Gibbs free energy change

ΔH enthalpy change

$ m-2 dollars per square meter

a crystallographic unit cell axis a

A cm-2 Ampère per square centimeter

Anal. analysis

bd broad (spectra)

calcd. calculated

°C celcius

cm2 s-1 square centimeter per second

d day

DOSY diffusion ordered spectroscopy

DMSO dimethylsulfoxide

d doublet (spectra)

DVB divinylbenzene

F(000) scaling coefficient for structure

factors

Fc calculated structure factor

Fo observed structure factor

FTIR flourier transform infrared

g/g gram per gram

g/mL gram per liter

Hz hertz

h hour

ICP inductively coupled plasma

J coupling constant (NMR)

kPa kilo paschal

LDPE low-density polyethylene

m/z mass-to-charge ratio

Mp melting point

meq g-1 milliequivalents per gram

mequi/g milliequivalents per gram

259

mmol millimole

Mrad milliradian

mmHg millimeter mercury

mol/L moles per liter

mol min-1 moles per minute

m multiplet (spectra)

NASA The National Aeronautics and

Space Administration

Ohm cm2 ohm per square centimeter

Rpm rounds per minute

S cm-1 siemens per centimeter

s singlet (spectra)

t triplet (spectra)

U temperature factor

U.S. United States

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