Mendham, Andrew P., Potter, Brian S., Palmer, Rex A., Dines, Trevor J., Mitchell, John C. ORCID: 0000-0003-2945-3292, Withnall, Robert and Chowdhry, Babur 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 (Print), 1097-4555 (Online) (doi:https://doi.org/10.1002/jrs.2426)

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Abstract

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 sim1493 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. Copyright © 2009 John Wiley & Sons, Ltd.

Item Type:	Article
Additional Information:	[1] Article first published online: 6 October 2009. [2] Published in print: February 2010. [3] Published as: Journal of Raman Spectroscopy, Volume 41, Issue 2, pages 148–159, February 2010. [4] The definitive version is available at www3.interscience.wiley.com.
Uncontrolled Keywords:	cyclic di-amino acid peptides, X-ray structure, X-ray crystallography, ab initio calculations, vibrational spectra
Subjects:	Q Science > QD Chemistry Q Science > QC Physics
Faculty / School / Research Centre / Research Group:	Faculty of Education, Health & Human Sciences > School of Human Sciences (HUM)
Related URLs:	Publisher Organisation
Last Modified:	09 Oct 2021 04:46
URI:	http://gala.gre.ac.uk/id/eprint/2078

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