Structural and vibrational analysis of glycyl-L-phenylalanine and phase transition under high-pressure

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2024-01, Vol.304, p.123383, Article 123383
• Main Authors: Avelar S. Silva, José, Militão Vasconcelos, Daniel L., Araújo de Lima, Raphaela, Cordeiro, Adrya J.P., Tarso C. Freire, Paulo
• Format: Article
• Language: English
• Subjects: DFT; Dipeptide; High-Pressure; Phase Transition
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2023.123383

[Display omitted] •Characterization of glycyl-l-phenylalanine by theoretical and experimental methods.•Torsion angle of |θ| = 110.8°.•Normal modes of vibration through density functional theory (DFT).•The phase transition is observed at 1.0 GPa. The structural and vibrational properties of the glycyl-L-phenylalanine dipeptide were investigated using vibrational spectroscopy (Raman and infrared) and first-principle calculations. Raman spectroscopy measurements were performed between 100 and 3200 cm−1 and infrared spectroscopy from 100 and 3200 cm−1 under ambient conditions. The conformational analysis of the zwitterionic form of the dipeptide was performed using the B3LYP functional, the 6–311++ base set and the Polarizable Continuum Model of solvation, determining the lowest energy conformation and assigning the vibrational modes. The effect of pressure on the glycyl-1-phenylalanine crystal was investigated using the Raman spectroscopy between 0.0 and -7.1 GPa in the spectral region of 100 – 3200 cm−1. As a result, conformational changes around 1.0 GPa were observed in the lattice modes and in some internal modes, showing a reorganization of the molecule in the crystal. In the decompression process, it was observed that the conformational change is reversible and the original Raman spectrum is recoverd.