Synthesis, Experimental and Theoretical (DFT) Characterization, Electrochemical Behavior, Antioxidant Evaluation, and Molecular Docking of New Ternary Ni(II) Complexes of Dimethylglyoxime and Some Amino Acids

Four new Ni(II) ion complexes were created from the interaction of dimethylglyoxime as a primary ligand and amino acids (lysine monohydrochloride, tryptophan, proline, and arginine) as a secondary ligand were investigated using various physicochemical studies such as elemental analysis, molar conductivity, infrared, and UV/vis. The molar conductance data confirm that all the complexes are non-electrolytic. The IR study shows that dimethylglyoxime is coordinated to the metal ion in a bidentate manner through NN donor sites of the oxime function. The amino acid is coordinated through the carboxylate oxygen and the N atom of the amino acid. The electronic spectral data indicated that the synthesized complexes have a square planar geometry, except for the complex with arginine, which has an octahedral structure. A complementary computational study using density functional theory (DFT) calculations was carried out to optimize the structures of the metal complexes and confirm the proposed geometries. The electrochemical behavior of the ligands and their metal complexes was determined by cyclic voltammetry. The study of the antioxidant properties of the complexes using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and molecular docking indicates that the complexes exhibit good antioxidant activity in comparison with ascorbic acid as a positive control.