Design and Synthesis of Pyridine Bis-Hydrazone Metal Complexes of Co(II), Cu(II), and Hg(II): Spectral, Gaussian, Electrochemical, Biological, Drug-Likeness and Molecular Docking Investigations

A bis-hydrazone ligand (H2DS) was synthesized via condensation of pyridine-2,6-dicarbohydrazide with salicylaldehyde and utilized to prepare a new series of Cu(II), Co(II), and Hg(II) metal chelates. All the prepared chelates were investigated using various assistive spectroscopic and microscopic tools including (1H, 13C -NMR, IR, UV-visible, ESR, XRD, EDX, SEM, and MS), elemental analysis, magnetic susceptibility, and thermal (TG/ DTA) analysis. Furthermore, all of the previous structural investigations were supported with theoretical studies based on DFT theory where the molecular modeling of the geometrically optimized structures was constructed through Gaussian 09 software. Various energy components such as (EBinding, EHOMO, and ELUMO) besides MEP (Molecular electrostatic potential), bond parameters (bond angle and bond length), dipole moment, and molecular chemical parameters were derived from the computational calculations. Moreover, the redox behavior of Cu(II) with/without the ligand (H2DS) was investigated using cyclic voltammetry. This technique is utilized to study the effect of the chelating agent on the attitude of the copper species in the solution universe. The impact of interaction is proved by changing in the potential of reduction/oxidation peaks alongside evaluating of both kinetic and thermodynamic stability. The produced hydrazone and its chelates were screened for antimicrobial activities (Escherichia coli, Staphylococcus aureus, and Candida albicans), antioxidant activities (DPPH and TAC), and cell viability MTT assay. Finally, the degree of efficiency of the binding that occurs between the different protein receptors and the ligand was estimated by molecular docking where the results showed a strong relationship with the biological investigations.