New nano-complexes of Zn(II), Cu(II), Ni(II) and Co(II) ions; spectroscopy, thermal, structural analysis, DFT calculations and antimicrobial activity application

Abstract

This work presents synthesis, characterization, and application of several metal (II) complexes with (E)-2-hydroxy-N/-((thiophen-2-yl)methylene)benzohydrazide (H2L). Prepared complexes were identified by elemental, thermal, FT-IR, UV–Vis, 1H NMR, and XRD analysis, as well as molar conductivity and magnetic moment measurements. Changes in FT-IR and 1H NMR spectra of hydrazone ligand upon coordination indicated that the ligand behaves the same way as a monoanonic ligand with ONS donor sites. Kinetic parameters were determined for each thermal degradation stage of the ligand and its complexes using ‘Coats–Redfern’ method. All results confirm that all prepared compounds have 1:2 metal-to-ligand stoichiometry except Zn(II) complex, which has 1:1 metal-to-ligand stoichiometry. The antimicrobial activity for complexes was investigated. The antimicrobial activity results revealed that Zn(II) complex (1) has a good potency against gram positive bacteria (E. coli) and gram negative bacteria (P. vulgaris) in comparision with doxymycin standard, AT B3LYP/6-311G (d,p) level, Density Functional Theory (DFT) calculations were carried out to investigate the optimized structure of both, the ligand and the complexes. Total energy, energy of HOMO, and LUMO as well as Mullikan atomic charges were calculated. Dipole moment, orientation, and structure activity relationship were performed and discussed.DFT calculations, moreover, confirmed practical antimicrobial results.