INTERAKSI RADIASI ELEKTROMAGNETIK DENGAN ATOM DAN MOLEKUL

METALOORGANIK

HILDA APRILIAKBK KIMIA FARMASI

PRODI FARMASI UNISBA

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RADIASI ELEKTROMAGNETIK (REM)

REM adalah kombinasi medan listrik dan medan magnet yang merambat dalam bentuk gelombang transversal

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RADIASI ELEKTROMAGNETIK (REM)

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DUALISME SIFAT REM

1. Sifat Gelombanga. difraksib. refraksic. rotasi

2. Sifat Foton* DASAR SPEKTROSKOPIa. absorpsib. emisi

*Foton = paket elektron berenergi

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SPEKTRUM ELEKTROMAGNETIK

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http://www.chm.davidson.edu/ronutt/che115/AO.htm

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1. Energi Translasi ( Et )

2. Energi Rotasi ( Er )

3. Energi Vibrasi ( Ev )

4. Energi Elektronik ( Ee )

>>E

ENERGI ATOM DAN MOLEKUL

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ENERGI ATOM DAN MOLEKUL

1.Energi Translasi (ET )

4. Energi elektronik (EE)

2. Rotasi (ER)

3. Energi Vibrasi (Ev)

X

Y

Z

x

y

z

Ground singlet state

Singlet excited state

R E M

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INTERAKSI REM - MATERI

Incident Radiation

Scattering

Material

Fluorescence

ReflectedRadiation

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ABSORBSI REM

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• Syarat absorpsi : perbedaan energi antara 2 tingkat energi sebanding dengan energi foton yang diserap.

E2-E1 = h.v ………………4)E1 = energi pada tingkat yang lebih rendahE2 = energi pada tingkat yang lebih tinggiV = frekuensi foton yang diabsorpsi

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ULTRAVIOLET INTERACTIONS

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VISIBLE LIGHT INTERACTIONS

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• Tingkat energi elektron singlet yang berada dalam keadaan dasar (singlet ground state) apabila dikenakan radiasi elektromagnetik akan mengalami eksitasi (singlet excited state) ke tingkat energi yang lebih tinggi.

• Perpindahan bersifat reversibel• Penyerapan radiasi ultraviolet dan sinar

tampak (visibel) dibatasi oleh sejumlah gugus fungsional (yang disebut dengan kromofor) yang mengandung elektron valensi dengan tingkat energi eksitasi yang relatif rendah

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antibonding

antibonding

nonbonding

bonding

bondings

p

n

s*

p*

Ener

gy

s →

s*

p →

p*

n →

s*

n →

p*

TRANSISI ELEKTRONIK MOLEKUL

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= k. P. a = 0,87 . 1020. P.a

Keterangan :

= absorbansi molark = konstantaP = kebolehjadiana = area of cross section of molecule 10Å2 (organic molecules)

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ε = 1 - 10 : sangat lemah 10 - 102 : lemah 102 - 103 : sedang

P < 0,01Forbiddentransition

P > 0,1 – 1Allowed transi-tion

ε = 103- 104 : kuat 104- 105 : sangat kuat

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APLIKASI

INFRARED (IR) INTERACTIONSVibrational transitions are associated with larger energies than ‘pure’ rotational transitions.

Vibrations can be subdivided into two classes, depending on whether the bond length or angle is changing:

• Stretching (symmetric and asymmetric)• Bending (scissoring, rocking, wagging and twisting)

Stretching frequencies are higher than corresponding bending frequencies (it is easier to bend a bond than to stretch or compress it)Bonds to hydrogen have higher stretching frequencies than those to heavier atoms.Triple bonds have higher stretching frequencies than corresponding double bonds, which in turn have higher frequencies than single bonds

INFRARED (IR) INTERACTIONS

Region Wavelength [µm]

Energy [meV]

Wavenumber [cm-1]

Type of excitation

Far IR 50 - 1000 1.2 - 25 10 – 200 Lattice vibrations,Molecular rotations

Mid IR 2.5 - 50 25 - 496 200 - 4000 Molecular vibrations

Near IR 1 - 2.5 496 - 1240 4000 - 10000 Overtones

INFRARED (IR) INTERACTIONS

• Quantum energy of IR photons (0.001-1.7 eV) matches the ranges of energies separating quantum states of molecular vibrations• Vibrations arise as molecular bonds are not rigid but behave like springs

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APLIKASI

MICROWAVE INTERACTIONS

• Quantum energy of microwave photons (0.00001-0.001 eV) matches the ranges of energies separating quantum states of molecular rotations and torsion• Note that rotational motion of molecules is quantized, like electronic and vibrational transitions associated absorption/emission lines

• Absorption of microwave radiation causes heating due to increased molecular rotational activity• Most matter transparent to µ-waves, microwave ovens use high intensity µ-waves to heat material

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X-RAY INTERACTIONS

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COMPTON SCATTERING

• An incoming photon is partially absorbed in an outer shell electron

• The electron absorbs enough energy to break the binding energy, and is ejected

• The ejected electron is now a Compton electron• Not much energy is needed to eject an electron

from an outer shell• The incoming photon, continues on a different

path with less energy as scattered radiation

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GAMMA RAY INTERACTIONS• Occurs at above 10 MeV• A high energy photon is absorbed by the nucleus• The nucleus becomes excited and becomes radioactive• To become stable, the nucleus emits negatrons, protons,

alpha particles, clusters of fragments, or gamma rays• These high energy photons are found in radiation

therapy

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RADIO FREQUENCY INTERACTIONS

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EMISI REM

• Emisi adalah proses dimana energi yang dihasilkan dari perpindahan elektron ke orbital yang lebih rendah akibat tumbukan dengan foton REM menghasilkan cahaya

Spektrum Emisi H

Spektrum Emisi Fe

CONTOH SPEKTRUM EMISI

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APLIKASI

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INTERAKSI REM DENGAN MOLEKUL METALOORGANIK

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METALOORGANIK

• Senyawa organologam : senyawa yg mengandung ikatan antara logam dan atom karbon

• Contoh : Ni(CO)4, Fe(CO)5 , Cr(C6H6)2, hemoglobin, klorofil

• Kebanyakan dihubungkan dengan senyawa kompleks logam transisi

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LOGAM TRANSISI

• Unsur logam dengan konfigurasi elektron pada sub kulit d yang tidak terisi sempurna

• Golongan 3 sampai 12 pada tabel periodik• Pada kenyataannya blok f juga dimasukkan

sebagai logam transisi, yaitu lantanida dan aktinida

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Splitting of d-orbital energies by an octahedral field of ligands

D is the splitting energy

The effect of ligand on splitting energy

eg

t 2g

eg

t 2g

weak field ligands

e.g. H2O

high spin complexes

strong field ligandse.g. CN-

low spin complexes

I- < Br- < S2- < SCN- < Cl-< NO3- < F- < OH- < ox2-

< H2O < NCS- < CH3CN < NH3 < en < bpy

< phen < NO2- < phosph < CN- < CO

The Spectrochemical Series

The Spin Transition

D D

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CONTOH APLIKASI

Heme grup B

Why are most plants green and then red or yellow in the fall?• Chlorophyll absorbs in the red and blue, and hence reflects in the green.

• Its absorption spectrum is due to electronic transitions

In the fall, trees produce carotenoids, which reflect yellow, and anthocyanins, which reflect orange and red.

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TERIMA KASIH