Synthesis, characterization, and computational analysis of chromium trioxide and amino acid-derived metal complexes

This study focused on the preparation and characterization of six metal-based complexes, synthesized through the reaction of chromium trioxide (CrO3) with a range of different amino acids in a methanol solvent. The amino acids investigated included glycine (Gly), L-alanine (Ala), L-serine (Ser), L-proline (Pro), L-cysteine (Cys), and S-methyl-L-cysteine (MeCys). The synthesis procedure of the CrO3-Amino acid complexes involved several steps: preparation of individual methanolic solutions of amino acids, addition of CrO3 solution, refluxing at approximately 65 °C for 3 hours, precipitation, separation, and purification of the final CrO3-Amino acid complexes. Infrared (FTIR) analysis suggested that the amino acids captured CrO3 through both amino and carboxylate groups. Thermal analysis offered insights into the two-stage degradation process of the synthesized CrO3-Amino acid complexes. Finally, the synthesized CrO3-Amino acid complexes were computationally analyzed, encompassing geometry optimization and energy parameter calculations using the density functional theory (DFT) method. The total energy calculations reveal that the synthesized CrO3-Amino acid complexes are more stable and have lower total energy compared to their corresponding free amino acids, suggesting the formation of more stable complexes. KEY WORDS: Metal complexes, Amino acids, CrO3, Thermal decomposition, Computational calculations, Geometry optimization Bull. Chem. Soc. Ethiop. 2025, 39(7), 1395-1410. DOI: https://dx.doi.org/10.4314/bcse.v39i7.12