Coordination chemistry and biological activity of nickel(II) and copper(II) ion complexes with nitrogen-sulphur donor ligands derived from S-benzyldithiocarbazate (SBDTC)

A bidentate and a quadridentate Schiff base having NS and NNSS donor sequences were prepared by condensing S-benzyldithiocarbazate (NH2NHCSSCH2Ph) with 23-butanedione (1:1 and 1:2 mole ratio). Ni-II and Cu-II complexes of these ligands were studied and characterised by elemental analyses and various physico-chemical techniques. The nickel complexes, [Ni(NS)(2)] and [Ni(SNNS)], were diamagnetic with square-planar and five-coordinate structures, respectively. The copper complex was, however, pentacoordinated. The ligands and the complexes were screened for anticancer activity against T-lymphoblastic leukemic cells (CEM-SS) and colon cancer cells (HT-29). The NS Schiff base was strongly active against leukemic cells with a CD50 value of 2.05 mug cm(-3). The nickel and copper complexes were found to be stronger antioxidants than Vitamin E.