Synthesis, characterization, and theoretical study of some divalent transition metal ions complexes with drug derivative

Novel complexes of Mn(II), Co(II), Ni(II), and Zn(II) with a dicloxacillin-derived ligand, 7-oxo-4-thia-1-azabicyclo[3.2.0]heptan-3-carboxylate (L), were synthesized and characterized using CHNS analysis, AAS, FTIR, UV-Vis, mass spectrometry, magnetic susceptibility, and conductivity measurements. Spectral and analytical data confirm that the ligand acts as a bidentate donor through oxygen and nitrogen atoms. Co(II) and Zn(II) complexes adopt tetrahedral structures, while Mn(II) and Ni(II) display octahedral coordination. Quantum chemical calculations (HyperChem 8.0.7) showed reduced HOMO-LUMO gaps and lower energy values upon complexation, reflecting improved stability. Theoretical vibration frequencies were consistent with experimental FTIR data. Antimicrobial screening at 5 mM revealed that the Co(II) complex exhibited the strongest inhibitory effect against Staphylococcus aureus, Escherichia coli, and Candida albicans, suggesting that metal coordination significantly enhances the biological activity of the ligand. KEY WORDS: Dicloxacillin derivative, Complexes derived from dicloxacillin, Biological activity, Theoretical study, Metal ions complexes Bull. Chem. Soc. Ethiop. 2026, 40(4), 929-938. DOI: https://dx.doi.org/10.4314/bcse.v40i4.14