Thermal, spectral and biological investigation of new nickel complexes with imidazole derivatives

Abstract

Four new Ni(II) complexes with acrylate and imidazole (Him) or imidazole derivatives [2-methylimidazole(2-MeIm)/5-methylimidazole(5-MeIm)/2-ethylimidazole(2-EtIm)] as ligands were prepared and characterized. All coordination compounds were characterized by elemental analysis, infrared (FTIR) and ultraviolet-visible-near-infrared (UV-Vis-NIR) spectroscopy, mass spectroscopy, magnetic moments measurements and thermal analysis (TG). The resulted complexes were formulated as follows: [Ni(HIm)2(acr)2] (1), [Ni(2-MeIm)2(acr)2(H2O)]·H2O (2), [Ni(5-MeIm)2(acr)2]·H2O· (3), [Ni(2-EtIm)2(acr)2(H2O)]·H2O (4). On the basis of magnetic moments measurements and on UV–Vis–NIR spectra, for all Ni(II) complexes was proposed an octahedral stereochemistry. Acrylate ions act as bidentate in complexes (1) and (3); meanwhile, in (2) and (4) they behave as bidentate and unidentate. Antimicrobial activity of complexes was investigated on ATCC reference and clinical microbial strains. The MIC (minimum inhibitory concentration) values revealed moderate antimicrobial activity of complex (1) against Enterococcus faecium and of complex (2) against Pseudomonas aeruginosa and Bacillus subtilis.