Synthesis, characterization and photoluminescence studies of a new Schiff base ligand and its nickel(II) complex

Schiff base ligands are considered privileged ligands because they are easily prepared by the condensation between active carbonyl groups and primary amines. Schiff base ligands are able to coordinate with many different metals, and form stabilizes complexes in various oxidation states [1]. These compounds also show a wide range of biological properties such as anticancer, antitumor, antifungal, antibacterial, antimalarial, antifilarial, antiviral and anti-HIV activities, Moreover, the biological activities of their complexes could be due to metal ion coordination. Metal complexes have been widely applied in clinics for centuries, although their molecular mechanism has not yet been entirely understood. Among different Schiff base complexes, nickel(II) imine complex has been shown to possess catalytic activity for the polymerization or copolymerization of olefins and vinylic monomers [2]. In this work, a new Schiff base ligand was synthesized from the 1:1 molar condensation of a novel ketone containing chelating ligand with cysteamine. Furthermore, the metal-toligand ratio was 1:1, and molar conductance data revealed that the nickel complex was nonelectrolyte. The free Schiff base ligand and its complex showed photoluminescence in methanol at room temperature. In the complex of this ligand, the sulfur group is used as a coordination site since oxidation of the SH group and formation of the disulfide bond were prevented by use of an inert atmosphere. The Schiff base ligand was coordinated to metal ion as a ligand through nitrogen and sulfur donor atoms. The Schiff base ligand and its nickel complex have been characterized by the elemental analysis and spectroscopic studies such as FT–IR, UV–Vis and 1H NMR.