Coordination chemistry and biological activity of bidentate and quadridentate nitrogen-sulfur donor ligands and their complexes

The ligand S-benzyldithiocarbazate (SBDTC) acts as a bidentate sulfur-nitro gen chelating agent. The reaction of Sn-II or Sb-III with SBDTC under alkal ine conditions gives complexes of composition [Sn(SBDTCA)(2)] . 2H(2)O and [Sb(SBDTCA)Cl-2 . 2H(2)O]. A quadridentate Schiff base of SBDTC with benzil , having a donor sequence SNNS, yields complexes, [Cd(SNNS)] and [Zr(O)(SNN S) . H2O]. The ligands and the complexes have been characterized by element al analyses, i.r., u.v.-vis., molar conductance measurements and H-1-n.m.r. spectroscopy. SBDTC, Sn-II and Sb-III complexes and the SNNS Schiff base t ogether with its Cd-II and Zr-IV complexes display significant antifungal, antibacterial and anti-cancer activity. The Sn-II complex and the SNNS free Schiff base were very effective against Melanoma (skin cancer cells). The SBDTC and its Sn-II complex were also very effective against Renal carcinom a (kidney cancer cells). The results have been compared with those of the u ncomplexed metal salts and the free ligands. The minimum concentrations for the evaluation of the above activities for CD50 of the samples were in the 1.0-15 mu g cm(-3) range.