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Conformational composition and population analysis of beta-alanine isolated in solid parahydrogen

TitleConformational composition and population analysis of beta-alanine isolated in solid parahydrogen
Publication TypeJournal Article
Year of Publication2015
AuthorsWong, YTAngel, Toh, SY, Djuricanin, P, Momose, T
JournalJOURNAL OF MOLECULAR SPECTROSCOPY
Volume310
Pagination23-31
Date PublishedAPR
ISSN0022-2852
Abstract

The conformational composition and the change in conformational ratio induced by UV irradiation of beta-alanine have been investigated using solid parahydrogen FT-IR matrix isolation spectroscopy for the first time. In order to assign the observed spectra, the vibrational wavenumbers and intensities of the eleven lowest energy beta-alanine conformers were calculated at the B3LYP/aug-cc-pVTZ level of theory. In-situ UV photo-irradiation of beta-alanine in solid parahydrogen was used to assist the spectral assignment. Out of the eleven lowest energy conformers, conformers I, II, III, IV, and VII were identified in the solid parahydrogen matrix, with conformer III observed in a matrix environment for the first time. Argon matrix FT-IR spectra of beta-alanine were also recorded for comparison and only four conformers, conformers I, II, IV and VII, were found, as reported previously. Conformational changes to higher energy structures were observed when beta-alanine was irradiated with UV radiation. These changes were more pronounced in parahydrogen matrices than in argon matrices, indicating the usefulness of solid parahydrogen matrix isolation spectroscopy for the conformational study of amino acids. (C) 2015 Elsevier Inc. All rights reserved.

DOI10.1016/j.jms.2015.01.002