New Cd(II) complex derived from (1-methylimidazol-2-yl) methanol: Synthesis, crystal structure, spectroscopic study, DFT and TD-DFT calculations, antimicrobial activity and free-radical scavenging capacity

Abstract

A combined experimental and theoretical study of new complex with a formula of [Cd(Hmim)2(OAc)2], where Hmim stands for (1-methyl-1H-imidazol-2-yl) methanol has been reported. The complex was characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR and UV-vis spectroscopy. The crystal structure of the complex shows that two Hmim and two carboxylate groups are coordinated to the Cd(II) ion in monodentate fashion through the nitrogen and carboxylic oxygen atoms displaying a distorted tetrahedral geometry. Detailed theoretical studies were performed using DFT and TD-DFT calculations, other properties such as chemical bonding analysis (QTAIM, RDG, DOS) have been also carried out and are in agreement with the experimental results. The ligand and its Cd(II) complex have been screened in vitro and evaluated for their potential as DPPH radical scavengers as well as antimicrobial agents against five pathogenic microorganisms such as Gram-positive and Gram-negative bacteria, a yeast and a fungus using the agar diffusion method. The SAR study showed that the free ligand exerts no inhibitory activity, except a moderate activity against the yeast, while the complex exhibits an antimicrobial activity more potent or similar to that of standard drugs against all selected microorganisms, and a moderate to interesting antioxidant potential compared to Vitamin C as control.