Phase transitions of L-histidinium hydrogen oxalate crystal under high pressures investigated by Raman spectroscopy

E K S Pinho; J G da Silva Filho; F F Sousa; P T C Freire; J A Lima; A O Dos Santos; P F F Filho

doi:10.1016/j.saa.2023.122800

Phase transitions of L-histidinium hydrogen oxalate crystal under high pressures investigated by Raman spectroscopy

Spectrochim Acta A Mol Biomol Spectrosc. 2023 Oct 5:298:122800. doi: 10.1016/j.saa.2023.122800. Epub 2023 May 1.

Authors

E K S Pinho¹, J G da Silva Filho¹, F F Sousa², P T C Freire³, J A Lima³, A O Dos Santos¹, P F F Filho⁴

Affiliations

¹ Centro de Ciências de Imperatriz, Universidade Federal do Maranhão, CEP, 65900-410 Imperatriz, MA, Brazil.
² Instituto de Ciências Exatas e Naturais, Universidade Federal do Pará, CEP, 66075-110 Belém, PA, Brazil.
³ Departamento de Física, Universidade Federal do Ceará, CEP, 60455-970 Fortaleza, CE, Braazil.
⁴ Centro de Ciências de Imperatriz, Universidade Federal do Maranhão, CEP, 65900-410 Imperatriz, MA, Brazil. Electronic address: freitasfacanha@gmail.com.

PMID: 37156174
DOI: 10.1016/j.saa.2023.122800

Abstract

L-histidinium hydrogen oxalate (L-HisH)(HC₂O₄) crystal is formed from amino acid. L-histidine with oxalic acid whose vibrational high pressures behavior have not yet been investigated in the literature. Here we synthesized (L-HisH)(HC₂O₄) crystal by slow solvent evaporation method in a 1:1 ratio of L-histidine and oxalic acid. In addition, a vibrational study of (L-HisH)(HC₂O₄) crystal as a function of pressure was performed via Raman spectroscopy in the pressure range of 0.0-7.3 GPa. From analysis of the behavior of the bands within 1.5-2.8 GPa, characterized by the disappearance of lattice modes, the occurrence of a conformational phase transition was noted. A second phase transition, now from structural type, close to 5.1 GPa was observed due to the incidence of considerable changes in lattice and internal modes, mainly in vibrational modes related to imidazole ring motions.

Keywords: High pressures; L-histidinium hydrogen oxalate; Phase transitions; Raman spectroscopy.