Spectroscopic studies, antimicrobial activity, and computational investigations of hydrazone ligands endowed metal chelates

Abstract

Our current efforts are aimed to synthesize 16 complexes of Co (II), Ni (II), Cu (II), and Zn (II) metal ions from heterocyclic hydrazone ligands by condensation reaction of 2,6‐diacetylpyridine with hydrazide derivatives to find out combating agent against microorganism diseases. The synthesized compounds were precisely characterized by various physicochemical and spectroscopic techniques like FT‐IR, UV–Vis, 1H and 13C NMR, magnetic susceptibility, ESR, mass spectrometry, powder XRD, TGA, and SEM that suggested the octahedral geometry of the complexes coordinating via enolic oxygen atoms, azomethine nitrogen atom, pyridine ring nitrogen atom of the hydrazone ligands, and oxygen atom of water molecule. The thermal stability of the complexes was demonstrated by thermal analysis revealing two‐step decompositions leaving behind metal oxide as an end residue. By using serial dilution method, the compounds (1–20) were tested for in vitro antimicrobial activity against four bacterial and two fungal pathogens. Among all the synthesized compounds, complex 16 was most active against B. subtilis, whereas complexes 13, 14, and 15 were most efficient for C. albicans. Moreover, the biological efficacy of H2L3 (3) ligand and its (13–16) complexes were demonstrated by computational methods like molecular docking, MESP, DFT, and ADMET studies that highlight that complexes have more potency than the ligands and may be employed as effective drug for pathogen‐induced malformations.