Unsymmetrical Schiff bases functionalize as bibasic tetradentate (ONNO) and monobasic tridentate (NNO) ligands on complexation with some transition metal ions

Three dissymmetrical Schiff bases have been prepared by the condensation of 2-hydroxyacetophenone, ethylenediamine and several aldehydes. The electronic transitions within these Schiff bases molecules and the effect of solvents of different polarities on these transitions have been investigated by UV/vis spectroscopy. Schiff bases complexes, binary 1:1 (metal:ligand) and ternary 1:1:1 (metal:ligand:Lewis base, where Lewis base = imidazole or pyridine), with transition metals, Co(II), Ni(II), Cu(II), and Zn(II) have been synthesized and characterized by elemental analysis, molar conductivity and electronic absorption and IR spectra. Further, the stoichiometric ratios of the complexes in solutions and the formation constants of the interaction of Schiff base ligands with metal ions have been determined. (c) 2007 Elsevier B.V. All rights reserved.