Inorganica Chimica Acta 357 (2004) 3211–3222

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Spectral properties and bio-activity of copper(II) clofibriates, partIII: crystal structure of Cu(clofibriate)2(2-pyridylmethanol)2,Cu(clofibriate)2(4-pyridylmethanol)2(H2O) dihydrate, and

Cu2(clofibriate)4(N,N-diethylnicotinamide)2q,qq

Jan Moncol a,*, Barbora Kalinakova b, Jozef Svorec a, Miroslava Kleinova c,Marian Koman a, Daniela Hudecova b, Milan Melnik a, Milan Mazur c, Marian Valko c

a Department of Inorganic Chemistry, Slovak Technical University, Radlinskeho 9, SK-81237 Bratislava, Slovakiab Department of Biochemistry and Microbiology, Slovak Technical University, SK-81237 Bratislava, Slovakia

c Department of Physical Chemistry, Slovak Technical University, SK-81237 Bratislava, Slovakia

Received 22 December 2003; accepted 28 March 2004

Available online 10 May 2004

Abstract

New copper(II) clofibriates (clof, {2-(4-chlorophenoxy)-2-methylpropionic or 2-(4-chlorophenoxy)isobutyric acid}) of compo-

sition Cu(clof)2L2 (where L¼ 2-pyridylmethanol (2-pymeth) (1), N-methylnicotinamide (Menia) (4), N,N-diethylnicotinamide

(Et2nia) (5), isonicotinamide (isonia) (7) or methyl-3-pyridylcarbamate (mpc) (8)), [Cu(clof)2(4-pymeth)2(H2O)] Æ 2H2O (4-py-

meth¼ 4-pyridylmethanol) (2 Æ 2H2O) and Cu(clof)2L (where L¼ 4-pymeth (3) or Et2nia (6)) have been prepared and spectro-

scopically characterized. All the Cu(clof)2L2 compounds seem to possess distorted octahedral copper(II) stereochemistry with

differing tetragonal distortions. An X-ray analysis of 1 was carried out and it featured a tetragonal-bipyramidal geometry around the

copper(II) atom. X-ray analysis of 2 Æ 2H2O featured a square-pyramidal geometry around copper(II) atom. Both the Cu(clof)2L

compounds seem to consist of a binuclear unit of tetracarboxylate type bridging. An X-ray analysis of 6 revealed typical binuclear

paddle-wheel type structure, consisting of two copper(II) atoms in square-pyramidal geometry bridged by four carboxylate anions in

the xy-plane. All complexes under study were characterized by EPR and electronic spectroscopy. The antimicrobial effects have been

tested on various strains of bacteria, yeasts and filamentous fungi.

� 2004 Elsevier B.V. All rights reserved.

Keywords: Copper; Carboxylate complexes; Crystal structure; Spectral properties; Biological activity; Hydrogen bonding network

1. Introduction

The interaction of the copper ions, which plays a vitalrole in a number of quite differential processes [2], and

their interaction with drugs administered for therapeutic

reasons is of considerable interest [3]. Phenoxyalkanoic

acids also play an important role in biological processes

as commercial auxin herbicide and/or anti-inflammatory

q In memory of Prof. Tadeusz Glowiak.qqFor part II, see [1].

* Corresponding author. Tel.: +4212593-25-186; fax: +4212524-93-

198.

E-mail address: Jan.moncol@stuba.sk (J. Moncol).

0020-1693/$ - see front matter � 2004 Elsevier B.V. All rights reserved.

doi:10.1016/j.ica.2004.03.043

agents [4]. Copper(II) phenoxyalkanoate complexes

have been shown to have diverse stereochemistry with

mononuclear [5,6], dinuclear [7] or polynuclear [8]structures.

Clofibric acid {2-(4-chlorophenoxy)-2-methylprop-

ionic or 2-(4-chlorophenoxy)isobutyric acid} (Scheme 1)

is a very interesting anti-inflammatory agent. Five cop-

per(II) clofibriate complexes were studied by X-ray dif-

fraction methods. X-ray diffraction analysis of

[Cu2(clof)4(ampy)2] [9] and [Cu2(clof)4(MeOH)2] [10]

shows that the compounds are binuclear with square py-ramidal geometry at each copper(II) centre. The two

copper(II) atoms are bridged by four carboxylate groups

in syn–syn configuration of four clofibriate anions, while

Fig. 1. Perspective view of complex [Cu(clof)2(2-pymeth)2] (1), with the

atom numbering scheme. Thermal ellipsoids are drawn at the 50%

probability level.

Scheme 1. Clofibric acid.

Table 1

Selected bond lengths (�A) and angles (�) for 1, 2 Æ 2H2O and 6

1

Cu–O1 1.998(2) Cu–N1 1.981(2)

Cu–O4 2.388(2)

O1–Cu–N1 89.30(7) O4–Cu–N1 76.81(7)

O1–Cu–O4 94.11(6) O1–Cu–O1i 180.0

O4–Cu–O4i 180.0 N1–Cu–N1i 180.0

2 Æ 2H2O

Cu–O1 1.967(1) Cu–N1 2.010(2)

Cu–O1W 2.281(3)

O1–Cu–N1 87.86(6) O1W–Cu–N1 95.11(4)

O1–Cu–O1W 91.00(4) N1–Cu–N1ii 169.74(9)

O1–Cu–O1ii 177.98(7)

6

Cu–O21 1.968(2) Cu–O22 1.985(2)

Cu–O11 1.980(2) Cu–O12iii 1.987(2)

Cu–N1 2.179(3) Cu � � �Cuiii 2.6481(9)

O11–Cu–N1 94.8(1) O12iii–Cu–N1 97.1(1)

O21–Cu–N1 95.7(1) O22–Cu–N1 95.7(1)

3212 J. Moncol et al. / Inorganica Chimica Acta 357 (2004) 3211–3222

the apical ligands are 2-aminopyrimidine in [Cu2(clof)4(ampy)2] [9] and methanol molecules in [Cu2(clof)4(MeOH)2] [10], respectively. The structures of

[Cu(clof)2L2], where L¼ pyridine (py) [10] or nicotin-

amide (nia) [11], are mononuclear and each copper(II)

atom has a tetragonal-bipyramidal environment with the

CuO4N2 chromophore. Two-dimensional coordination

polymer is a [Cu(clof)2(3-pymeth)2]n complex [1] (where3-pymeth¼ 3-pyridylmethanol); the coordination envi-

ronment about the copper atom is tetragonal bipyramidal

with CuO4N2 chromophore.

The antibacterial and antifungal activities of a range

of copper(II) carboxylates with N-donor or O-donor

ligands have been evaluated against several fungi and

bacteria by our group [11,12] and other authors [13]. In

this paper, we investigate the preparation of 2-pyridyl-methanol (2-pymeth), 4-pyridylmethanol (4-pymeth), N-

methylnicotinamide (Menia), N,N-diethylnicotinamide

(Et2nia), isonicotinamide (isonia) and methyl-3-pyr-

idylcarbamate (mpc) compounds of copper(II) clofibri-

ate. The complexes were characterized by elemental

analysis, electronic and EPR spectra. The crystal and

molecular structure of [Cu(clof)2(2-pymeth)2], [Cu(clof)2(4-pymeth)2(H2O)] Æ 2H2O and [Cu2(clof)4 (Et2nia)2] wasdetermined. The X-ray data are compared and discussed

with those found for similar copper(II) carboxylates.

The role of different types of hydrogen bond interactions

in crystal packing is discussed as well. Bioactivity of the

complexes was tested on Staphylococcus aureus, Esche-

richia coli, Candida parapsilosis, Rhizopus oryzae, Al-

ternaria alternata, Botrytis cinerea, and Microsporum

gypseum.

O11–Cu–O21 87.9(1) O11–Cu–O22 90.5(1)

O11–Cu–O12 167.9(1) O21–Cu–O22 168.5(1)

O12iii–Cu–O21 88.9(1) O12iii–Cu–O22 90.4(1)

Symmetry code: (i) �xþ 1=2;�y þ 1=2;�z; (ii) �x; y;�zþ 1=2;

(iii) �xþ 1;�y;�z.

2. Results and discussion

2.1. Crystal and molecular structures

The structure of the complex [Cu(clof)2(2-pymeth)2]

(1): The molecular structure of 1 is shown in Fig. 1 andselected bond distances and bond angles are given in

Table 1. The crystal structure consists of discrete units

of [Cu(clof)2(2-pymeth)2]. The stereochemistry around

the central copper(II) atom is axially elongated octahe-

dral. The molecule of 1 is centrosymmetric with the

copper(II) atom being surrounded by two nitrogen at-

oms coming from two different 2-pyridylmethanol

molecules [Cu–N1¼ 1.981(2) �A] and two carboxylate

oxygen atoms from two different clofibriate anions [Cu–

O1¼ 1.998(2) �A] in a square-planar arrangement. The

methanol oxygen atoms of two 2-pyridylmethanol

molecules complete the distorted octahedral coordina-tion of the copper(II) atom [Cu–O4¼ 2.388(2) �A]. The

intramolecular hydrogen bond O4–H17� � �O2 (Table 2)

creates a six-membered metalocycle and stabilizes the

molecular structure. The complex [Cu(salicylato)2(2-

pymeth)2] has a very similar structure, as well as struc-

tural parameters to complex 1 [14].

Table 2

Parameters in (�A) and (�) of hydrogen bonds within the structure 1, 2 Æ 2H2O and 6

D–H� � �A d(D–H) d(H� � �A) d(D� � �A) \(DHA) Symmetry code

1

O3–H17� � �O2 0.81(3) 1.80(3) 2.595(2) 169(3)

C13–H12. . .O2 0.93(3) 2.58(2) 3.195(3) 124(2) �xþ 1=2; y � 1=2;�zþ 1=2

C14–H13� � �O1 0.92(3) 2.55(2) 3.412(3) 157(2) �xþ 1=2;�y � 1=2

C10–H5� � �Cl 0.92(3) 3.07(3) 3.877(3) 147(2) �xþ 1;�y þ 1;�z

2 Æ 2H2O

O2W–H19� � �O1 0.83(3) 1.97(3) 2.799(2) 177(2) x; y þ 1; zO2W–H20� � �O2 0.77(3) 2.28(3) 2.935(2) 142(2)

O2W–H20� � �O3 0.77(3) 2.42(3) 3.103(2) 147(2)

O1W–H18� � �O2 0.83(3) 2.00(3) 2.808(2) 166(3) x; y � 1; zO4–H17� � �O2W 0.81(3) 1.92(3) 2.715(2) 166(3)

C15-H14� � �O2 0.93(2) 2.51(2) 3.311(2) 144(2)

6

C1–H1� � �O22 0.91(3) 2.59(3) 3.170(5) 122(2)

C5–H5� � �O21 0.92(3) 2.66(3) 3.225(5) 120(2)

C18–H18� � �O11 0.86(3) 2.41(3) 3.059(5) 132(3)

C24–H24� � �O21 0.92(4) 2.47(4) 3.122(5) 128(3)

C14–H14� � �O1 0.97(3) 2.69(3) 3.386(5) 129(2) �xþ 3=2; y � 1=2

C8–H8C� � �O13 0.91(6) 2.65(6) 3.538(7) 166(5) �xþ 2;�y;�z

J. Moncol et al. / Inorganica Chimica Acta 357 (2004) 3211–3222 3213

In Fig. 2 is drawn the crystal packing of 1 in the cell,

viewed perpendicular to the bc-plane. In the crystal

structure, weak C–H� � �O hydrogen bonds [15] [C13–

H12� � �O2; C14–H13� � �O1] and weak C–H� � �Cl hydro-gen bond [16] [C10–H5� � �Cl] (Table 2) dominate the

packing of molecules 1. A relatively short Cl� � �Cl in-teraction [17] [Cl� � �Cl¼ 3.773(2) �A ð�xþ 1; y;�z� 1=2Þwas also observed.

The structure of the complex [Cu(clof)2(4-py-

meth)2(H2O)] Æ 2H2O (2 Æ 2H2O): The molecular structure

of 2 Æ 2H2O is shown in Fig. 3 with selected bond dis-

tances and bond angles given in Table 1. Themolecules of

Fig. 2. View of the packing 1 in the cell, viewed perpendicular to the

bc-plane; hydrogen atoms are omitted for clarity.

Fig. 3. Perspective view of complex [Cu(clof)2(4-pymeth)2(H2O)] Æ2H2O (2 Æ 2H2O), with the atom numbering scheme. Thermal ellipsoids

are drawn at the 50% probability level.

2 are monomeric, five coordinate with square pyramidal

stereochemistry (Fig. 3). The coordination sphere around

each copper(II) ion consists of two oxygen atoms from

the carboxyl groups of unidentate clofibriate anions [Cu–

O1¼ 1.967(1) �A] and two nitrogen atoms from 4-pyr-

idylmethanols [Cu–N1¼ 2.010(2) �A] forming the basal

plane. The fifth coordination position is provided by awater oxygen atom [Cu–O1W¼ 2.281(3) �A]. The Cu

atom is 0.107(1) �A above the equatorial plane O1–N1–

O1i–N1i towards the water oxygen atom O1W. For this

type of five-coordinated structure, the parameter s[s ¼ ða� bÞ=60], (where a and b are the equatorial an-

gles) was introduced [18]. The value s is 0 for perfectly

tetragonal geometry and 1 for perfectly trigonal-bipyra-

midal geometry. In this case s ¼ 0:137. The square-py-ramidal stereochemistry is known among nitrogen base

Fig. 5. View of the packing of 2 Æ 2H2O, viewed perpendicular to the ac-

plane; hydrogen atoms are omitted for clarity.

3214 J. Moncol et al. / Inorganica Chimica Acta 357 (2004) 3211–3222

adducts of copper(II) phenoxyalkanoates, where

four complexes, aqua-bis(2-fluorophenoxyacetato)-

bis(pyridine)copper(II) [6a], aqua-bis(4-chloro-2-

methylphenoxyacetato)-bis(pyridine) copper(II) [6b],

aqua-bis(phenoxyacetato)-bis(pyridine) copper(II) [6c]and aqua-bis(4-aminopyridine)bis(2-nitrophenoxyace-

tato)copper(II) [6d] have the same five-coordination with

crystallography imposed twofold symmetry. All four

complexes have tetragonal geometry with s parameters of

0.147, 0.143, 0.167 and 0.242, respectively.

The crystal structure of [Cu(clof)2(4-pymeth)2(H2O)] Æ2H2O (2 Æ 2H2O) are dominant strong O–H� � �O hydro-

gen bonds. Fig. 4 is shown a complicated system ofstrong hydrogen bonds. The molecule [Cu(clof)2(4-py-

meth)2(H2O)] and a water molecule (O2W) are con-

nected by strong hydrogen bonds [O2W–H19� � �O1;

O2W–H20� � �O2; O2W–H20� � �O3; O1W–H19� � �O2W]

(Table 2). This system of hydrogen bonds is more

complicated than the network of hydrogen bonds in

complexes [Cu(4-bromobenzoato)2(pyridine)2(H2O)]

[19a], [Cu(terephthalate)(pyridine)2(H2O)] [19b],[Cu(cinnamate)2(pyridine)2(H2O)] Æ pyridine [19c], [Cu-

(2-butenoate)2(imidazole)2(H2O)] [19d] and [Cu(levuli-

nate)2(pyridine)2(H2O)] [19e]. A different view of strong

hydrogen bonds is shown in Fig. 5.

Structure of the complex [Cu2(clof)4(Et2nia)2] (6): The

X-ray analysis of [Cu2(clof)4(Et2nia)2] 6 reveals a cen-

trosymmetric tetracarboxylic dimeric core structure with

the two N,N-diethylnicotinamide ligands in apical posi-tions (Fig. 6). Selected bond distances and bond angles of

6 are given in Table 1. Four bidentate clofibriate anions

form syn–syn bridges between isolated pair of copper

atoms separated by [Cu� � �Cui ¼ 2.6481(9) �A], it is typical

for non-bonding character [20]. The copper atom to

Fig. 4. View of the system of strong O–H� � �O hydrogen bonds of

2 Æ 2H2O; hydrogen atoms are omitted for clarity.

carboxylate oxygen atoms distances are from 1.968(2) to

1.987(2) �A, the copper atom to pyridine nitrogen atom of

N,N-diethylnicotinamide is [Cu–N1¼ 2.179(3) �A]. Thecopper atom is displaced 0.202(1) �A toward the N,N-

diethylnicotinamide from the plane containing the four-

coordinated oxygen atoms. The s value [17] of 0.011

implies perfect tetragonal geometry. The molecular

structure of 6 is very similar to those observed in

[Cu2(acetato)4(Et2nia)2], [Cu2(benzoato)4(E2nia)2] and

[Cu2(octanoato)4(Et2nia)2] [21]. Similar dimeric com-

plexes with phenoxyalkanoic acid copper carboxylatesare reported in which the N-donor ligand pyridine [22]

and 2-aminopyrimidine [9,23] occupy apical positions.

In the crystal structure of 6 (Fig. 7) are dominant

only weak C–H� � �O hydrogen bonds [15] [C14–

H14� � �O1; C8–H8C� � �O13] and short Cl� � �Cl interac-tion [16] [Cl1� � �Cl2¼ 3.483(2) �A ðx; y; z� 1Þ].

2.2. UV–Vis spectra

The solid-state electronic spectra of Cu(clof)2L2

complexes (1, 4, 5, 7, 8) exhibit a broad ligand field band

with a maximum in the range of 560–660 nm as well as a

shoulder in the range of 710–730 nm (4 and 8). These

electronic d–d transitions are typical for tetragonal ar-

rangements around copper(II) atoms [24]. Maxima of

these bands are consistent with other copper(II) carb-oxylates with a trans-CuIIN2O2O2 chromophore [25].

The solid-state electronic spectrum of 2 Æ 2H2O is very

similar to those observed for Cu(clof)2L2 complexes and

exhibit a broad band with a maximum at 620 nm.

Maximum of the band is consistent with other copper(II)

carboxylates with a tetragonal arrangement around

copper(II) atom and CuIIN2O2O chromophore [26].

Fig. 6. Perspective view of complex [Cu2(clof)4(Et2nia)2] (6), with the atom numbering scheme. Thermal ellipsoids are drawn at the 50% probability

level.

Fig. 7. View of the packing of 6 in the cell, viewed perpendicular to the ac-plane; hydrogen atoms are omitted for clarity.

J. Moncol et al. / Inorganica Chimica Acta 357 (2004) 3211–3222 3215

The solid-state electronic spectra of both complexes

Cu(clof)2L show a broad absorption band (band I) in

the visible region (757 nm for 3 and 717 nm for 6).These bands were assigned to dxz;yz–dx2�y2 transitions

[27]. Moreover, the spectra of both complexes display

shoulders at 429 and 400 nm (band II). This band is

broad due to a shoulder observed at lower energies

originating from the dz2–dx2�y2 transition, which is

typical of Jahn-Teller distorted Cu(II) complexes [28].

The other strong band and shoulder around 230–380

nm (band III) has been assigned to a charge-transfer

LMCT absorption [29] and is believed to be indicativeof a dimeric complex [29] even though a number of

monomeric and polymeric Cu(II) compounds exhibit

this band [30]. Finally, both complexes display bands I,

II and III in the usual range observed for Cu(II)

compounds in a square-pyramidal CuIIO4O0 and

CuIIO4N environment [12,31].

3216 J. Moncol et al. / Inorganica Chimica Acta 357 (2004) 3211–3222

2.3. EPR spectra

2.3.1. Monomeric strucutures

The EPR spectra of monomeric complexes are of the

normal axial type, exhibiting allowed transitions(DMs ¼ 1) characteristic of species with S ¼ 1=2. The gtensor components obtained from these spectra exhibit

1000 2000 3000 4000

Bmon

BZ

1

B(x2

Magnetic Field /

2000 2500 3000 3

exp

sim

Magnetic Field /

2000 2500 3000

1500 2000 2500 3000 3500 4000

Magnetic Fiel

(a)

(b)

(c)

Fig. 8. First-derivative EPR powder spectra at room temperature of: (a) [C

using spin Hamiltonian parameters in Table 3, (b) [Cu2(clof)4(4-pymeth)2spectrum; inset: forbidden transitions measured with increased sensitivity (5

g? < gk; in agreement with the elongated pseudo-octa-

hedral geometry having a dx2�y2 ground state [32].

For complexes 4 and 5, copper hyperfine splitting

structure (ICu ¼ 3/2) is nicely resolved (Fig. 8(a)). This

points to reduced copper–copper dipolar interaction in 4and 5 and an effective diamagnetic shielding of copper

atom by Menia and Et2nia ligands, respectively.

5000 6000 7000

Bz

2

,y2)

Gauss

500 4000 4500 Gauss

3500 4000 4500

d / Gauss

u(clof)2(Et2nia)2] (5) experimental spectrum and computer simulation

] (3), (c) [Cu(clof)2(4-pymeth)2(H2O)] Æ 2H2O (2 Æ 2H2O) experimental

00·).

Table 3

EPR spin Hamiltonian parameters for studied complexesa

Complex g? gk g3 Ak (G) D (cm�1) gk=jAkj (cm) a2

g1 g2

1 2.074 2.079 2.314

2 Æ 2H2O 2.054 2.058 2.271

3 2.076 2.364 0.3938

4 2.031 2.081 2.276 175 139 0.86

5 2.053 2.289 165 149 0.85

6 2.061 2.330 0.3727

7 2.087 2.285 �170b �144 �0.85

8 2.075 2.265a The EPR spectra were measured in polycrystalline form at room temperature.b The parallel hyperfine splitting structure not satisfactorily resolved.

J. Moncol et al. / Inorganica Chimica Acta 357 (2004) 3211–3222 3217

EPR spectra were evaluated by assuming an effective

D4h local symmetry of the complexes. For the anti-

bonding molecular orbital in this symmetry group con-

taining the unpaired electron, we may write the

following equation [33]:

wb1g ¼ adx2�y2 � a0vðx2 � y2Þ; ð1Þ

where d and v functions represent copper(II) 3d orbitals

and ligand-group orbitals of the appropriate symmetry,

respectively [33].

The molecular orbital coefficient a can be related to

the parallel component of the hyperfine splitting tensor

A according to the following equation [34]:

a2 ¼ �ðAk=P Þ þ ðgk � 2Þ þ ð3=7Þðg? � 2Þ þ 0:04; ð2Þwhere P is the dipole coefficient of the free ion and other

symbols have usual meaning [35].

The coefficient a2 characterizes the covalency of the

r-in plane bond and was calculated from the above Eq.(2) for both complexes 4 and 5, which show resolved

parallel hyperfine splitting structure in their EPR spec-

tra. The calculated values are summarized in Table 3.

They imply that the nature of the bonding in th com-

plexes 4, 5 and 7 is not purely ionic and that there is

appreciable in-plane covalent r bonding.

2.3.2. Dimeric structures

The EPR spectra of complexes 3 and 6 are typical of

the triplet state type (Fig. 8(b)) and were interpreted

using the spin Hamiltonian for S ¼ 1 [35]

H ¼ bB�gS þ D S2z

�� 1

2SðS þ 1Þ

�þ EðS2

x � S2y Þ; ð3Þ

where D and E are the zero-field splitting (ZFS) parame-

ters; x, y, and z are the principal-axes coordinate system

fixed with respect to the Cu–Cu bond, and the other

symbols have their usual meaning [35]. The calculated

EPR data for these complexes are given together with the

monomeric structures in Table 3. The EPR spectra of the

studied complexes 3 and 6 revealed axial symmetry; the

ZFS parameter E is therefore equal to zero.

Of specific type is the EPR spectrum of complex

2 Æ 2H2O. The EPR spectrum recorded under typical

spectrometer settings (gain and modulation field) shows

axially resolved spectrum pointing to a monomeric

structure, in agreement with the X-ray data. However,

EPR scan with high gain (500·) shows weak features

typical for half-field,DMs ¼ 2, forbidden transitions. This

indicates that there is an appreciable interaction betweencopper(II) centres (copper–copper distance¼ 6.6 �A),

most probably through space [36]. The calculated values

of gk=Ak summarized in Table 3 for 4, 5 and 7 indicated

marked tetrahedral distortions around copper atom.

2.4. Antimicrobial activities

Results of the quantitative determination of antimi-crobial activity, characterized by IC50 and MIC values,

of the selected copper(II) clofibriates are summarized in

Table 4. As can be seen, the inhibition activities increase

in the sequences: 4> 1> 7> 8> 2 Æ 2H2O > 6 against

model microorganisms. Complexes 4 and 7 had the

highest antibacterial inhibition activity. The sensitivity

of Gþ S. aureus to the tested compounds was two times

higher than that of G� E. coli. Copper(II) complexesvary greatly in their antifungal activity. C. parapsilosis

was greatly inhibited by 4 and 7. Complexes 1, 2 Æ 2H2O,

7 and 8 influenced the colony morphology of A. alter-

nata. Changes of colony colour were probably caused by

defects in biosynthesis of melanin. Ramification effect

on growing hyphal tips of B. cinerea was observed by

complexes 1, 2 Æ 2H2O, 4, 6 and 7, a fungus most sensi-

tive to tested compounds was M. gypseum.

3. Experimental

3.1. Preparation of the complexes

3.1.1. [Cu(clof)2(2-pymeth)2] (1)The complex 1 was prepared by addition of 2-pyridyl-

methanol (0.02 mol) to copper(II) clofibriate (0.01 mol) in

Table

4

AntimicrobialactivityofCu(II)

complexes

characterized

bythenumericalvalues

ofIC

50(m

moll�

1)andMIC

(mmoll�

1)

Bacteria

Yeasts

Filamentousfungi

S.aureus

E.coli

C.parapsilosis

R.oryzae

A.alternata

B.cinerea

M.gypseum

IC50

MI

IC50

MI

IC50

MI

IC50

MI

IC50

MI

IC50

MI

IC50

MI

12.00

5a

3.30

>5

2.70

>5

inact

inact

3.00

>5

1.45

2.5

a

2Æ2H

2O

4.25

>5

3.80

>5

3.20

>5

3.40

>5

4.80

>5

3.70

>5

2.70

5a

41.65

2.5

b3.75

>5

2.20

5b

2.80

>5

2.50

>5

1.70

5b

1.85

2.5

a

63.05

>5

inact

inact

inact

3.35

5a

3.30

>5

2.5

5a

71.55

2.5

b2.95

5b

2.40

5b

2.30

5a

2.25

5a

3.20

>5

3.30

5a

81.60

2.5

binact

3.30

5b

2.05

5b

2.70

5b

inact

2.15

5a

aConcentrationinducingamicrobicidaleffect(M

MC),inact

–inactivecompound(IC

50>5mmoll�

1).

bConcentrationinducingamicrobistaticaleffect.

3218 J. Moncol et al. / Inorganica Chimica Acta 357 (2004) 3211–3222

hot acetone. The mixture was stirred, filtered and left to

cool and stand at room temperature. A blue product pre-

cipitated, which was collected; recrystallization from ace-

tone solution gave air stable crystals. Anal. Calc. for

[Cu(clof)2(2-pymeth)2] (1): C, 54.20; H, 4.83; N, 3.95; Cu,8.96. Found: C, 54.4; H, 4.6; N, 3.8; Cu, 8.95%. IR

masym(COO)1609, msym(COO)1402 cm�1.UV–Vis: 620nm.

3.1.2. [Cu(clof)2(4-pymeth)2(H2O)] � 2H2O (2 � 2H2O)

The complex 2 Æ 2H2O was prepared by addition of

methanol solution of 4-pyridylmethanol (0.02 mol) to

copper(II) clofibriate (0.01 mol) in hot acetone. The

mixture was stirred, filtered and left to cool and stand atroom temperature. A blue product precipitated, which

was collected; recrystallization from acetone solution

gave air stable crystals. Anal. Calc. for [Cu(clof)2(4-py-

meth)2(H2O)] Æ 2H2O (2 Æ 2H2O): C, 50.37; H, 5.28; N,

3.67; Cu, 8.33. Found: C, 50.4; H, 5.4; N, 3.6; Cu,

8.28%. IR m(OH) 3348, masym(COO) 1618, msym(COO)

1398 cm�1. UV–Vis: 620 nm.

3.1.3. [Cu2(clof)4(4-pymeth)2] (3)The complex 3 was prepared by addition of methanol

solution of 4-pyridylmethanol (0.01 mol) to copper(II)

clofibriate (0.01 mol) in hot methanol. The mixture was

stirred, filtered and left to cool and stand at room

temperature. A green product precipitated, which was

collected; recrystallization from acetone solution gave

air stable crystals. Anal. Calc. for [Cu2(clof)4(4-py-meth)2] (3): C, 52.05; H, 4.54; N, 2.33; Cu, 10.59. Found:

C, 51.9; H, 4.4; N, 2.4; Cu, 10.35%. IR m(OH) 3472,

masym(COO) 1620, msym(COO) 1418 cm�1. UV–Vis: 235,

257, 429 (sh), 757 nm.

3.1.4. [Cu(clof)2(Menia)2] (4)The complex 4 was prepared by addition of N-

methylnicotinamide (0.02 mol) to copper(II) clofibriate(0.01 mol) in hot acetone. The mixture was stirred, fil-

tered and left to cool and stand at room temperature. A

blue product precipitated, which was collected; recrys-

tallization from aceton–N,N-diethylnicotinamide (8:1)

solution gave air stable crystals. Anal. Calc. for

[Cu(clof)2(Menia)2] (4): C, 53.51; H, 4.75; N, 7.34; Cu,

8.33. Found: C, 53.2; H, 4.9; N, 4.7; Cu, 8.41%. IR

m(NH) 3248, masym(COO) 1604, msym(COO) 1409 cm�1.UV–Vis: 562, 725 (sh) nm.

3.1.5. [Cu(clof)2(Et2nia)2] (5)The complex 5 was prepared by addition of methanol

solution of N-methylnicotinamide (0.02 mol) to cop-

per(II) clofibriate (0.01mol) in hotmethanol. Themixture

was stirred, filtered and left to cool and stand at room

temperature. A violet product precipitated, which wascollected; recrystallization from acetone solution gave air

J. Moncol et al. / Inorganica Chimica Acta 357 (2004) 3211–3222 3219

stable crystals. Anal. Calc. for [Cu(clof)2(Et2nia)2] (5): C,

56.70; H, 5.71; N, 6.61; Cu, 7.50. Found: C, 56.7; H, 5.9;

N, 6.5; Cu, 7.36%. IR masym(COO) 1607, msym(COO) 1394

cm�1. UV–Vis: 603 nm.

3.1.6. [Cu2(clof)4(Et2nia)2] (6)The complex 6 was prepared by addition of N,N-di-

ethylnicotinamide (0.01 mol) to copper(II) clofibriate

(0.01 mol) in hot methanol. The mixture was stirred,

filtered and left to cool and stand at room temperature.

A green product precipitated, which was collected; re-

crystallization from methanol solution gave air stable

crystals. Anal. Calc. for [Cu2(clof)4(Et2nia)2] (6): C,53.86; H, 5.12; N, 4.19; Cu, 9.50. Found: C, 53.9; H, 4.9;

N, 4.2; Cu, 9.43%. IR masym(COO) 1628, msym(COO) 1414

cm�1. UV–Vis: 230, 273, 400 (sh) 717 nm.

3.1.7. [Cu(clof)2(isonia)2] (7)The complex 7 was prepared by addition of methanol

solution of isonicotinamide (0.02 mol) to copper(II)

clofibriate (0.01 mol) in hot acetone. The mixture wasstirred, filtered and left to cool and stand at room

temperature. A blue product precipitated, which was

collected; recrystallization from acetone solution gave

air stable crystals. Anal. Calc. for [Cu(clof)2(isonia)2]

(7): C, 52.29; H, 4.39; N, 7.62; Cu, 8.64. Found: C, 52.4;

H, 4.5; N, 7.7; Cu, 8.59%. IR masym(NH2) 3400,

masym(NH2) 3169, masym(COO) 1610, msym(COO) 1397

cm�1. UV–Vis: 660 nm.

3.1.8. [Cu(clof)2(mpc)2] (8)The complex 8 was prepared by addition of methanol

solution of methyl-3-pyridylcarbamate (0.02 mol) to

copper(II) clofibriate (0.01 mol) in hot acetone–metha-

nol solution (4:1). The mixture was stirred, filtered and

left to cool and stand at room temperature. A violet

product precipitated, which was collected; recrystalliza-tion from acetone solution gave air stable crystals. Anal.

Calc. for [Cu(clof)2(mpc)2] (8): C, 51.36; H, 4.56; N,

7.05; Cu, 7.99. Found: C, 51.1; H, 4.6; N, 7.1; Cu,

8.09%. IR m(NH) 3243, masym(COO) 1617, msym(COO)

1403 cm�1. UV–Vis: 579, 719 (sh) nm.

3.2. Chemical reagents, analysis and spectral studies

All the chemicals used were of analytical grade

(Aldrich or Sigma) and were used without further

purification.

Copper was determined by electrolysis after miner-

alization of the complexes; carbon, hydrogen, nitrogen

and sulfur were determined by microanalytical methods

(Carlo Erba Instruments EA 1108). Besides the ele-

mental analysis, the water content in hydrates was de-termined from thermogravimetrical curves.

Electronic spectra of the powdered samples in nujol

mulls were recorded at room temperature on Specord

M40 and Specord 200, respectively. IR spectra were

recorded on a FT Magna 750 spectrophotometer at

room temperature. Spectra of solid samples were ob-tained in nujol mulls, KBr and polyethylene pellets at a

resolution of 1 cm�1.

The X-band (�9.4 GHz) EPR spectra in polycrys-

talline solid state were recorded on a Bruker EMX

spectrometer equipped with a Bruker variable temper-

ature unit. Line positions were measured accurately

using internal field markers generated by an NMR

gaussmeter, while the microwave frequency was mea-sured by a microwave frequency counter; 100 kHz

magnetic field modulation (peak-to-peak amplitude� 3

G) was used. All EPR measurements were done using

cylindrical quartz sample tubes with 3.5 mm o.d. (ca. 3.0

mm i.d.). Additional details were published elsewhere

[37].

The simulations of the EPR spectra were performed

using the commercially available program SimFonia(Bruker) [38] and/or program QPOWQPOW developed by Prof.

Belford, University of Illionois [39].

3.3. Structure determination

Data collection at 100 K and cell refinement were

carried out using a a-axis diffractometer Kuma KM-4

CCD with graphite monochromated MoKa radiation.The diffraction intensities were corrected for Lorentz

and polarization factors. The structures were solved

by Patterson methods for 1 using DIRDIFDIRDIF-99 [40] or

direct methods for 2 Æ 2H2O and 6 using SIRSIR-97 [41].

Geometrical analysis was performed using SHELXLSHELXL-97

[42]. Empirical absorption correction was made by

using XABSXABS-2 [43]. The structure of the complexes 1,

2 Æ 2H2O and 6 was drawn by ORTEPORTEP-3 for Windows[44]. The Single Crystal Suite WINGXWINGX [45] was used as

an integrated system for all the crystallographic pro-

grams and software used to prepare material for

publication. Crystal data and conditions of data col-

lection and refinement are reported in Table 5.

3.4. Bio-tests

The antimicrobial activity of the compounds under

investigation was evaluated by a microdilution method

[46] using Gþ bacteria S. aureus (CCM 3824) and G�

bacteria E. coli (CCM 3988). The effects of these com-

pounds on the yeasts C. parapsilosis (Laboratory of

Medical Mycology, Postgraduate Medical Institute,

Bratislava, Slovakia) were determinated by the macro-

dilution method in L-shaped tubes [47]. The cultures ofthe bacteria and yeasts were incubated under vigorous

shaking.

Table 5

Crystallographic data for compounds 1, 2 Æ 2H2O and 6

Complex 1 2 Æ 2H2O 6

Formula C32H34Cl2N2O8Cu C32H40Cl2N2O11Cu C30H34Cl2N2O7Cu

Crystal dimensions (mm) 0.25· 0.20· 0.15 0.20· 0.10· 0.10 0.20· 0.15· 0.10M 709.05 763.10 669.03

T (K) 100(2) 100(2) 100(2)

Crystal system monoclinic monoclinic monoclinic

Space group C2=c C2=c P21=na (�A) 26.698(2) 30.399(5) 13.8410(14)

b (�A) 7.2399(5) 6.638(5) 12.8140(14)

c (�A) 16.790(1) 21.248(5) 18.9998(18)

b (�) 101.120(7) 101.98(3) 111.537(9)

V (�A3) 3184.4(4) 3527(3) 3134.5(5)

Z 4 4 4

Absorption corrections XABS-2 XABS-2 XABS-2

Tmin, Tmax 0.4940, 0.9248 0.7430, 0.9264 0.7567, 0.9105

Dcalc (Mg m�3) 1.479 1.437 1.418

l (Mo Ka) (mm�1) 0.907 0.831 0.915

F ð000Þ 1468 1588 1388

h Range (�) 3.66–25.00 3.54–25.00 3.38–25.00

Reflections collected 8868 9773 10783

Unique reflections (Rint) 2757 (0.0282) 3086 (0.0254) 2884 (0.0309)

S 1.095 1.085 1.079

R1a (observed reflections) 0.0382 0.0283 0.0302

wR2b (all reflections) 0.09779 0.0619 0.0791

aR1 ¼P

ðjFoj � jFcjÞ=P

jFoj:bwR2 ¼

PwðF 2

o � F 2c Þ

2h i

=P

wðF 2o Þ

2n o1=2

, w ¼ 1=½r2ðF 2o Þ þ ðaPÞ2 þ bp�, where P ¼ ðF 2

o þ 2F 2c Þ=3.

3220 J. Moncol et al. / Inorganica Chimica Acta 357 (2004) 3211–3222

The efficiency of prepared derivatives on filamentous

fungi R. oryzae (Collection of Microorganisms of De-

partment of Biochemistry and Microbiology, Faculty of

Chemical and Food Technology, Slovak University of

Technology), B. cinerea (CCMF-16); A. alternata

(CCMF-128) and M. gypseum (Laboratory of Medical

Mycology, Postgraduate Medical Institute, Bratislava,Slovakia), was tested by macrodilution technique on

solidified broth medium during static culturing [47].

Chromatographically pure compounds were dis-

solved in dimethyl sulfoxide, its final concentration

never exceeded 1.0% (v/v) in either the control or the

treated samples. The concentration of the tested com-

pounds ranging from 0.63 to 5 mmol l�1 for filamentous

fungi, yeasts and bacteria was used in experiments.The antimicrobial activity was characterized by IC50

values (concentration of the compound which, in com-

parison to the control, inhibits the growth of microor-

ganisms to 50%) and MIC values (minimal inhibitory

concentration of the compound which inhibits microbial

growth by 100%). The IC50 and MIC values were ob-

tained from the toxicity curves.

MIC experiments on subculture dishes were used toassess the minimal microbicidal concentration (MMC).

Subcultures were prepared separately in Petri dishes

containing complete agar medium and incubated at 30

�C for 48 h (bacteria, yeasts) and at 25 �C for 96 h

(filamentous fungi). The MMC values were taken as the

lowest concentration that showed no visible growth of

microbial colonies in the subculture dishes.

4. Conclusion

A series of eight new copper(II) clofibriates with

pyridylmethanol, N-methylnicotinamide, N,N-diethyl-

nicotinamide, isonicotinamide and methyl-3-pyridylc-

arbamate have been prepared and spectroscopically

characterized. X-ray analysis of two monomeric com-plexes ([Cu(clof)2(4-pymeth)2(H2O)] Æ 2H2O and [Cu

(clof)2(2-pymeth)2]) and a dimeric complex ([Cu2(clof)4(Et2nia)2]) was determined. In [Cu(clof)2(4-pymeth)2-

(H2O)] Æ 2H2O, the copper atom has five coordinate

square pyramidal stereochemistry, while in [Cu(clof)2(2-

pymeth)2], the copper atom has six-coordinate elongated

tetragonal bipyramidal stereochemistry. An X-ray

analysis of [Cu2(clof)4(Et2nia)2] revealed typical binu-clear paddle-wheel type structure, consisting of two

copper(II) atoms in square-pyramidal geometry bridged

by four carboxylate anions in the xy-plane. Similar type

of structure has been proposed for Cu2(clof)4(4-py-

meth)2. The crystal structure of [Cu(clof)2(4-pymeth)2-

(H2O)] Æ 2H2O revealed a complicated system of strong

O–H� � �O hydrogen bonds connecting [Cu(clof)2(4-py-

meth)2(H2O)] moiety via the non-coordinating watermolecules. All the studied Cu(clof)2L2 (L¼N-methyl-

nicotinamide, N,N-diethylnicotinamide, isonicotinamide

or methyl-3-pyridylcarbamate) compounds seem to

possess distorted octahedral copper(II) stereochemistry

with differing tetragonal distortions, similarly to pyri-

dine [10] and nicotinamide [11] copper clofibriate ana-

logues. The antimicrobial effect of selected complexes

J. Moncol et al. / Inorganica Chimica Acta 357 (2004) 3211–3222 3221

has been tested on various strains of bacteria, yeasts and

filamentous fungi.

5. Supplementary material

Crystallographic data (excluding structure factors)

for the structures reported in this paper have been de-

posited with the Cambridge Crystallographic Data

Centre as supplementary publication nos. CCDC-

217665 (1), CCDC-217666 (2 Æ 2H2O) and CCDC-

217667 (6). Copies of the data can be obtained free of

charge on application to the CCDC, 12 Union Road,Cambridge CB2 1EZ, UK [fax: (internat.) +44-0-1223/

336033; e-mail: deposit@ccdc.cam.ac.uk].

Acknowledgements

We thank the Slovak Grant Agency for financial

support (Grant Nos. 1/9251/02 to M.M., 1/9256/02 toM.V. and 1/0109/03 to L.M.).

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