Silva RF, Luz-Lima C, Freire PTC, Melo FEA, Pinheiro GS. High-temperature Raman spectra of dipeptide α-L-aspartyl-L-alanine crystal.
SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023;
297:122746. [PMID:
37086536 DOI:
10.1016/j.saa.2023.122746]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 04/04/2023] [Accepted: 04/11/2023] [Indexed: 05/03/2023]
Abstract
Crystals of dipeptide α-L-aspartyl-L-alanine (α-Asp-Ala), C7H12N2O5, were studied under high-temperature conditions through vibrational spectroscopy (IR and Raman) and thermal analysis (Differential Scanning Calorimetry - DSC). From the analysis of the results, it is possible to conclude that: (i) the studied material undergoes a reversible order-disorder phase transition at 373 K on heating, where several changes were observed in the vibrational spectra, especially with vibrational modes of the units that participate directly of the hydrogen bonds; (ii) the phase transition undergone by the α-Asp-Ala crystal (about 373 K) involves changes in hydrogen bonds, possibly the rupture of at least one of them, and change in the conformation of the molecules in the unit cell.
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