Stability and Antimicrobial Activity of Transition Metal (II) Complexes with SNO and ONO Functionalized Ligand: A Computational Study

In this work, the structural, surface potential, and antimicrobial aspects of a set of recently synthesized and published complexes of five transition metals(II) are investigated using the semiempirical PM6 and B3LYP/6-31G* methods. The complexes ML2 [M = Ni, Cu, and Zn] are mainly composed of 2-thiophenecarbaldehyde isonicotinoyl hydrazone containing a trifunctional SNO-donor system. Experimentally, the complexes were synthesized and characterized using their conductivity, IR, and partially using 1H NMR, and MS spectra, where they show similar properties to those in their analogous NNO functionalized ligand and ONO donor ligand. The attained wavefunction for each of the complexes was subsequently used to compute six molecular descriptors which were then investigated in light of their reported antimicrobial activities against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The findings are further explored to elucidate the impact of the structural features on the complex biological activity. It is concluded that the type of transition metal is significantly impacting the antimicrobial activity of the complex, where the structural features of Mn(II) counterpart complexes were computationally inspected and their untested biological activities was predicted.