Structural, spectroscopic, electrochemical and antibacterial studies of some new nickel(II) Schiff base complexes

Three new complexes of Ni(II) with tridentate Schiff base ligand, have been synthesized from reaction of the ligand sapH(2) (salicylidene-2-aminophenol) with Ni(OAc)2 center dot 4H(2)O in the presence of relevant amine: imidazole (1), 1-methylimidazole (2), and morpholine (3). These complexes have been characterized by FT-IR, H-1 NMR, elemental analysis and UV-Vis spectroscopy. The crystal structures of the complexes were established by X-ray crystallography. The single crystal X-ray diffraction studies show square planar geometry around Ni(II) in all three complexes, and conform to the results obtained by spectroscopic studies. The electrochemical investigation of these complexes at a carbon paste electrode in water solution indicates that the Ni(II/III) oxidation process was irreversible. Our studies showed that the nickel complexes exhibit good antibacterial activity, and their antibacterial activity is higher than that of the ligand against both gram positive and gram negative bacteria. (C) 2015 Elsevier B.V. All rights reserved.