Synthesis,characterization, thermal and redox behavior,and biological activity of Ni(II), Cu(II), and Zn(II) complexes containing pyridoxine and imidazole moieties

Several mixed ligand complexes [M(II)(PN)(B)] [M(II) = Ni(II), Cu(II), and Zn(II)] derived from pyridoxine (PN) and imidazoles (B), namely imidazole (him), benzimidazole (bim), histamine (hist), and L-histidine (his), were synthesized. The complexes are characterized by elemental analysis, IR, UV-Vis ¹H NMR, and ESR spectroscopy. In [M(II)(PN)B], the monovalent anion of PN is bidentate to M(II) (–O, –OH), him, bim monodentate (–N), hist bidentate (–N, –N), and his tridentate (–O, –N, –N). Magnetic moment studies showed that the Ni(II) complexes and Cu(II)–PN–his have octahedral configuration while the other Cu(II) complexes have distorted tetrahedral geometry. The g _∥/A _∥ values calculated from the X-band ESR spectra of Cu(II) complexes in DMSO at 300 and 77 K supports the geometry. The thermal behavior (TG/DTA) of the synthesized complexes indicates the presence of lattice as well as coordinated water in the complexes. The in vitro biological activity of the mixed ligand complexes was tested against common bacteria, yeast, and fungi. The results in comparison with the control indicate that most of the complexes exhibit higher biological activities. The oxidative DNA cleavage studies of the mixed ligand complexes were performed using gel electrophoresis.