Syntheses, structures and biological activities of square planar Ni(II), Cu(II) complexes

Abstract Ni(II) and Cu(II) complexes of a tridentate Schiff base ligand, N -(2-hydroxyphenyl)-3-methoxy-salicylideneamine ( H 2 L ) have been synthesized and characterized by IR, NMR, UV–Vis spectroscopy and elemental analysis. The solid state structures of complexes have been determined by single crystal X-ray diffraction analyses. The molecular structures shows the formation of mononuclear complexes [(NiL(1Me-Im)] ( 1 ), [(CuL(1Me-Im)] ( 2 ) and [(NiL(PPh 3 )] ( 3 ) (1Me-Im = 1-methylimidazole and PPh 3  = triphenylphosphine). The Ni(II) or Cu(II) ion is situated in a square planar environment and coordinated by the NO 2 donors of the Schiff base ligand and 1Me-Im ( 1 – 2 ) or PPh 3 ( 3 ). The interactions of complexes 1 – 3 with DNA have been investigated by EtBr displacement experiments and spectroscopic titrations. The MTT assay showed no significant toxicity of 1 , 3 and increasing toxicity of 2 at lower concentration.