Espectroscopias Raman e infravermelho dos cristais de aminoácidos L-metionina dopada com Ni e L-fenilalanina dopada com Mn

Abstract

In the present work, we investigate the structural and vibrational properties of amino acid crystals, L-methionine and L-phenylalanine, doped with transition elements Nickel (Ni) and Manganese (Mn). The crystals were obtained using the slow evaporation method at room temperature, and X-ray diffraction measurements, as well as Raman and Infrared spectroscopy, were employed. The X-ray diffraction results of the doped amino acid crystals were compared with those of pure amino acids, and the diffractograms show good agreement. The Raman and Infrared spectroscopy results of the doped amino acid crystals were identified based on the results of pure crystals and similar amino acids found in the literature. Regarding the theoretical vibrational spectra, they show good agreement with the experimental vibrational spectra, as well as their vibration frequencies. The molecular structures were created and modeled using Avogadro and MolView software, DFT (Density Functional Theory) calculations were performed using the B3LYP functional with the 6-311++g(d,p) basis set, and PED calculations were used to classify the normal vibration modes and normal coordinates of L-methionine doped with Ni and L-phenylalanine doped with Mn molecules.