Report No xxxx - Instytut Fizyki JÄ drowej PAN
Report No xxxx - Instytut Fizyki JÄ drowej PAN
Report No xxxx - Instytut Fizyki JÄ drowej PAN
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DSC measurements confirm existing of L-alanine / Polyethylene Glycol complex.<br />
Melting temperature for the complex (578K) is lower then that for pure L-Alanine (588K),<br />
and in the DSC diagram, due to low concentration, is not observed a melting peak for the pure<br />
Polyethylene Glycol.<br />
The infrared spectra for L-Alanine / Polyethylene Glycol in KBr matrix were recorded<br />
on BRUKER IFS 66/s FTIR Spectrometer in the temperature range from 143K to 547K.<br />
Characteristic Polyethylene Glycol absorption band is observed at ~1115 cm -1 – C-O-C<br />
symmetric stretching vibration (Fig.2) [3].<br />
0,8<br />
Mobility of this molecular group increases<br />
0,7<br />
with increasing temperature.<br />
Bands at ~1650 and ~1550 cm -1 are due to<br />
0,6<br />
symmetric stretching C=O (Fig.3) and<br />
0,5<br />
143K<br />
stretching CO-NH (Fig.4) vibrations,<br />
163K<br />
0,4<br />
183K<br />
ν<br />
203K<br />
s<br />
(C-O-C)<br />
respectively. It corresponds to formation<br />
0,3<br />
223K<br />
253K<br />
273K<br />
of L-Alanine / Polyethylene Glycol<br />
0,2<br />
293K<br />
313K<br />
complex [3]. Mobility of the C=O group<br />
333K<br />
0,1<br />
353K<br />
373K<br />
increases with increasing temperature,<br />
0,0<br />
whereas CO-NH bond, which links<br />
1130 1120 1110 1100<br />
Wavenumber [cm<br />
Polyethylene Glycol part with L-Alanine<br />
-1 ]<br />
part of complex, is very stiff. Shifting of Fig.2. Polyethylene Glycol absorption<br />
the absorption maximum as a function<br />
band of νs(C-O-C) vibration<br />
temperature is not observed.<br />
Transmittance [a.u.]<br />
Transmittance [a.u.]<br />
0,2<br />
0,1<br />
ν s<br />
(C=O)<br />
0,0<br />
1670 1660 1650 1640 1630<br />
Wavenumber [cm -1 ]<br />
143K<br />
163K<br />
183K<br />
203K<br />
223K<br />
253K<br />
273K<br />
293K<br />
313K<br />
333K<br />
353K<br />
373K<br />
Fig.3. L-Alanine/Polyethylene Glycol<br />
absorption band of νs(C=O) vibration<br />
Transmittance [a.u.]<br />
0,4<br />
0,3<br />
0,2<br />
ν(CO-NH)<br />
143K<br />
163K<br />
183K<br />
203K<br />
223K<br />
253K<br />
273K<br />
293K<br />
313K<br />
333K<br />
353K<br />
373K<br />
0,1<br />
1560 1550 1540 1530<br />
Wavenumber [cm -1 ]<br />
Fig.4. L-Alanine/Polyethylene Glycol<br />
absorption band of ν(CO-NH) vibration<br />
References:<br />
[1] Guiotto A., Pozzobon M., Sanavio C., Schiavon O., Orsolini P.; Veronese F.M., Bioorganic<br />
&Medicinal Chemistry Letters 12 (2002) 177-180<br />
[2] Andrew E.R., Hinshaw W.S., Hutchins M.G., Sjoblom R.O.I., Canepa P.C., Molecular Physics 32<br />
(1975) 795<br />
[3] Yuan M., Deng X.; European Polymer Journal 37 (2001) 1907-1912<br />
44
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