Theoretical and Biological Evaluations of Vanadyl, Cobalt and Copper Chelates: DFT, Molecular Docking and Antimicrobial Investigations

Abstract

New biologically active complexes of VO^IV, Co^II and Cu^II were synthesized and characterized by CHNS, FTIR, mass, magnetic susceptibility, DRS and EPR techniques. The ligand precursor was synthesized by the reaction between o-phenylenediammine and thiophene-2-carbaldehyde, which was subsequently coordinated with metal ions (VO^IV, Co^II and Cu^II) to synthesize the complexes with the general formula [M(C₃₂H₂₄N₄S₄)]X₂ [M = VO^IV, Co^II and Cu^II; X = Cl, SO₄^2–]. The coordination process followed a 2:1 (ligand-to-metal) stoichiometry for VO(IV), Co(II) and Cu(II) complexes. Structural analysis suggested a square pyramidal geometry for vanadium, an octahedral arrangement for cobalt and a square planar configuration for copper. Additionally, DFT-based computational methods were performed to evaluate key quantum chemical parameters and some biological descriptors of the ligand and its metal complexes. The antibacterial screening against E. coli, S. aureus, B. subtilis and P. aeruginosa showed that all the metal complexes displayed significantly enhanced antimicrobial activity compared to the uncoordinated ligand. To gain further insight into protein-ligand interactions, in silico docking analyses were performed and the ADME study was used to confirm their drug-like properties, reinforcing their potential as bioactive agents.