The temperature-dependent single-crystal Raman spectroscopy of a model dipeptide: L-Alanyl-L-alanine.

Autor: Silva JG; Departamento de Física, Universidade Federal do Ceará, C.P. 6030, CEP 60455-760 Fortaleza, CE, Brazil., Arruda LM; Departamento de Física, Universidade Federal do Ceará, C.P. 6030, CEP 60455-760 Fortaleza, CE, Brazil., Pinheiro GS; Departamento de Física, Universidade Federal do Ceará, C.P. 6030, CEP 60455-760 Fortaleza, CE, Brazil; Departamento de Física, Campus Ministro Petrônio Portella, Universidade Federal do Piauí, CEP 64049-550 Teresina, PI, Brazil. Electronic address: gardenia@fisica.ufc.br., Lima CL; Departamento de Física, Campus Ministro Petrônio Portella, Universidade Federal do Piauí, CEP 64049-550 Teresina, PI, Brazil., Melo FE; Departamento de Física, Universidade Federal do Ceará, C.P. 6030, CEP 60455-760 Fortaleza, CE, Brazil., Ayala AP; Departamento de Física, Universidade Federal do Ceará, C.P. 6030, CEP 60455-760 Fortaleza, CE, Brazil., Filho JM; Departamento de Física, Universidade Federal do Ceará, C.P. 6030, CEP 60455-760 Fortaleza, CE, Brazil., Freire PT; Departamento de Física, Universidade Federal do Ceará, C.P. 6030, CEP 60455-760 Fortaleza, CE, Brazil.
Jazyk: angličtina
Zdroj: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy [Spectrochim Acta A Mol Biomol Spectrosc] 2015 Sep 05; Vol. 148, pp. 244-9. Date of Electronic Publication: 2015 Apr 11.
DOI: 10.1016/j.saa.2015.04.010
Abstrakt: A single-crystal of peptide L-alanyl-L-alanine (C6H12N2O3) was studied by Raman spectroscopy at low-temperature, and a tentative assignment of the normal modes was given. Evidence of a second order structural phase transition was found through Raman spectroscopy between the temperatures of 80K and 60K. Group theory considerations suggest that the transition leads the sample from the tetragonal to a monoclinic structure. Additionally, our study suggests that the mechanism for the structural phase transition is governed by the occupation of non-equivalent C1 local symmetry sites by the CH3 molecular groups. Analysis based on group theory suggests L-alanyl-L-alanine presents C2 symmetry at low temperatures.
(Copyright © 2015 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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