Mendham, A.P. and Potter, B.S. and Palmer, Rex A. and Dines, T.J. and Mitchell, J.C. and Withnall, R. and Chowdhry, B.Z. (2009) Vibrational spectra and crystal structure of the di-amino acid peptide cyclo(L-Met-L-Met): comparison of experimental data and DFT calculations. Journal of Raman Spectroscopy 41 (2), pp. 148-159. ISSN 0377-0486.Full text not available from this repository.
Experimental Raman and FT-IR spectra of solid-state non-deuterated and N-deuterated samples of cyclo(L-Met-L-Met) are reported and discussed. The Raman and FT-IR results show characteristic amide I vibrations (Raman: 1649 cm−1, infrared: 1675 cm−1) for molecules exhibiting a cis amide conformation. A Raman band, assigned to the cis amide II vibrational mode, is observed at ∼1493 cm−1 but no IR band is observed in this region. Cyclo(L-Met-L-Met) crystallises in the triclinic space group P1 with one molecule per unit cell. The overall shape of the diketopiperazine (DKP) ring displays a (slightly distorted) boat conformation. The crystal packing employs two strong hydrogen bonds, which traverse the entire crystal via translational repeats. B3-LYP/cc-pVDZ calculations of the structure of the molecule predict a boat conformation for the DKP ring, in agreement with the experimentally determined X-ray structure.
|Keyword(s) / Subject(s):||cyclic di-amino acid peptides, X-ray structure, X-ray crystallography, ab initio calculations, vibrational spectra|
|School or Research Centre:||Birkbeck Schools and Research Centres > School of Science > Biological Sciences|
|Date Deposited:||01 Apr 2011 11:00|
|Last Modified:||17 Apr 2013 12:20|
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