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-nitrogen chelating agent. The reaction of Sn^sup II^ or Sb^sup III^ with SBDTC under alkaline conditions gives complexes of composition [Sn(SBDTCA)^sub 2^] · 2H^sub 2^O and [Sb(SBDTCA)Cl^sub 2^ · 2H^sub 2^O]. A quadridentate Schiff base of SBDTC with benzil, having a donor sequence SNNS, yields complexes, [Cd(SNNS)] and [Zr(O)(SNNS) · H^sub 2^O]. The ligands and the complexes have been characterized by elemental analyses, i.r., u.v.-vis., molar conductance measurements and ^sup 1^H-n.m.r. spectroscopy. SBDTC, Sn^sup II^ and Sb^sup III^ complexes and the SNNS Schiff base together with its Cd^sup II^ and Zr^sup IV^ complexes display significant antifungal, antibacterial and anti-cancer activity. The Sn^sup II^ complex and the SNNS free Schiff base were very effective against Melanoma (skin cancer cells). The SBDTC and its Sn^sup II^ complex were also very effective against Renal carcinoma (kidney cancer cells). The results have been compared with those of the uncomplexed metal salts and the free ligands. The minimum concentrations for the evaluation of the above activities for CD^sub 50^ of the samples were in the 1.0-15 μg cm^sup -3^ range.[PUBLICATION ABSTRACT]