A new dithiocarbazate ligand, S-2-picolyldithiocarbazate (S2PDTC) was synthesized using 2picolylchloride hydrochloride. Tridentate Schiff bases were prepared by condensation of S-2picolyldithiocarbazate (S2PDTC) with pyridine-2-carboxaldehyde (NNS′), 2-acetylpyrrole (NNS″) and 2-acetylthiophene (NSS), while a bidentate Schiff base (NS) was prepared by condensing the S2PDTC with 2-acetylfuran. Complexes of S2PDTC and its Schiff bases with Ni(II) salts were synthesized and characterized by elemental analyses and various physicochemical techniques. A square-planar structure has been proposed for the diamagnetic [Ni(S2PDTC)2] and [Ni(NNS″) • Cl] complexes while [Ni(NS) • Cl] complex was dimeric. Complexes of [Ni(NNS′)2] and [Ni(NSS)2] were paramagnetic with octahedral stereochemistry. S2PDTC showed activity against bacteria and fungi (inhibitory zones above 15 mm). The NS and NSS Schiff bases showed activity toward a number of the bacteria assayed, while the NS and NSS Schiff bases, and the [Ni(NNS″) • Cl] and [Ni(NS) • Cl] complexes were found to be active only against C. lypolytica (2075). S2PDTC proved moderately active against HT-29 and weakly active toward CEM-SS with CD50 values of 9.5 and 24.0 μg cm−3, respectively, while among its Schiff bases reported herein, only the NNS′ Schiff base showed strong activity toward CEM-SS (Human cell T-lymphoblastic leukemia) and HT-29 (Human colon adenocarcinoma cells) with CD50 values of 2.3 μg cm−3. All of the Ni(II) complexes were inactive against CEM-SS cancer cells.

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Condensation of SMDTC with 2-furyl-methylketone and 5-methyl-2-furaldehyde gave isomeric Schiff bases, (NS) and (NS'). The metal complexes of these uninegatively charged bidentate Schiff base ligands with cadmium, tin, iron, lead and cobalt have been prepared. The complexes have been characterized by a variety of physico-chemical techniques. X-ray crystallographic analysis shows that the Cd(II) complex, bis[S-methyl-β-N-(2furylmethylketone)dithiocarbazato]cadmium(II), consists of two molecules with distorted octahedral structure. The Co(II) complexes are paramagnetic with a square-planar stereochemistry. The diamagnetic Sn(II), Fe(III) and Pb(II) complexes also have squareplanar structures while the diamagnetic [Cd(NS')2]. 3H2O complex is tetrahedral. The [Cd(NS')2].3H2O, [Sn(N'S)2) and [Co(NS)2] showed clear inhibition of almost all bacteria and fungi tested However, [Cd(NS)2], [Fe(NS)]Cl2, [Pb(NS)2] and [Pb(NS')2] were inactive against all bacteria assayed while [Cd(NS)2], [Fe(NS)]Cl2 and [Pb(NS)2] showed clear inhibition of some fungi. The [Cd(NS)2], [Cd(NS')2].3H2O and [Co(NS)2] were found to be very active against Human cell T-lymphoblastic leukemia (CEM-SS) and cervical cancer cells (HELA) with CD50 values between 1.8 and 3.6 μl cm-3.