Synthesis, characterization, spectroscopic study and biological evaluation of Zn(II), Ni(II), and Cu(II)complexes derived from(1-methyl-1H-imidazol-2-yl)methanol

Abstract

This study focuses on the synthesis, the structural studies of four new divalent metal coordination complexes of (1-methyl-1H-imidazol-2-yl)methanol (Hmim), and the assessment of their antimicrobial activity against five pathogenic microorganisms as well as their antioxidant potential. M(II) complexes were prepared by condensation of Hmim with Zn(OAc)2, Cu(OAc)2, NiCl2·6H2O, or CuCl2 in dry 1,2-dimethoxyethane at rt.. The ligand and its complexes have been characterized systematically by elemental analysis, FT-IR and UV–vis spectroscopy, and single-crystal X-ray diffraction. In [Zn(Hmim)2(OAc)2] (1)four donor atoms surround the metal ion displaying tetra-coordinated compound in distorted tetrahedral geometry, while in [Cu(Hmim)3OAc].AcOH (2), the Cu(II) ion is coordinated by three Hmim ligands and one acetate ligand displaying a tetragonally distorted octahedral environment. In [Ni(Hmim)2(H2O)2]Cl2(3), and [Cu(Hmim)3]Cl2 (4), the ligand is coordinated to M(II) ions in bidentate fashion exhibiting a distorted octahedral environment, the chloride anions act only as counter ions. The free ligand and its complexes 1–4 were tested in vitro for their antimicrobial activity against the growth of five strains including Gram (+) and Gram (-) bacteria, a Gram (+) phytopathogenic bacteria, a yeast and a fungus using the agar diffusion method. The SAR study of the antibacterial activity revealed significant differences in their inhibition activity profile, where 1 gave the best results displaying significant inhibition effects with a broad spectrum. The free-radical scavenging activity of synthesized compounds was investigated through their DPPH radical scavenging capacity, and has shown moderate to interesting antioxidant potential.