Synthesis, Spectroscopic, Antimicrobial Activity and Computational Studies of Some Homoleptic and Heteroleptic Metal(II) Complexes of 2-Furoic Acid Hydrazone

Homoleptic Co(II), Cu(II) and Ni(II) complexes of a hydrazone derived from 3-acetyl-2-hydroxy-6-methyl-4H-pyran-4-one (dehydroacetic acid) and 2-furoic acid hydrazide, and their heteroleptic analogues with 2,2 '-bipyridine were synthesized. The complexes were characterized by spectroscopic methods (ESI-MS, IR and NMR), elemental analysis, magnetic susceptibility and molar conductance measurements. The homoleptic complexes adopted octahedral geometry, while the heteroleptic analogous had four-coordinate tetrahedral (Co and Cu complexes) and square-planar (Ni complex) geometries. The homoleptic complexes were non-electrolytes, while the heteroleptic complexes were 1:1 electrolytes in DMSO. Antimicrobial experiments indicated that [Cu(L)(2)] and [Cu(L)(bipy)](CH3COO) had the best antibacterial activities, with MIC of 31.2 and 61.5 mu g/ml against Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212, respectively. Molecular docking determined that [Cu(L)(bipy)]CH3COO had the highest binding energy and hydrogen bonding interactions with one of the active sites of amino acid residue (LEU73). Density functional theory (DFT) calculations of the complexes revealed that [Cu(L)(bipy)]CH3COO possessed low energy gap, suggesting a higher activity and ability to donate electrons to electron-accepting species of biological targets.