Syntheses, structures and anti-tumor activity of four organotin(iv) dicarboxylates based on (1,3,4-thiadiazole-2,5-diyldithio)diacetic acid

Four novel organotin complexes, [(Me3Sn)(2)(O2CCH2S)(2)C2N2S](n) (1), [(Me2Sn)(2)(O2CCH2S)(2)C2N2S((3)-O)](n) (2), [(n-Bu3Sn)(2)(O2CCH2S)(2)C2N2S](n) (3) and [(n-Bu2Sn)(O2CCH2S)(2)C2N2S](n) (4), derived from flexible (1,3,4-thiadiazole-2,5-diyldithio)diacetic acid (H(2)tzda), have been synthesized and characterized by elemental analysis, FT-IR, NMR and X-ray crystallography. The structural analysis reveals that complexes 1 and 2 display a 1D pipeline-like and 1D ladder chain structure, respectively. Complex 1 contains interconnected 26-membered macrocycles, while complex 2 is made up of the typical ladder tetraorganodistannoxane unit containing 26-membered macrocycles. In addition, the molecules of complexes 1 and 2 are further linked through intermolecular C-HO interactions into a 3D and 2D infinite supramolecular structure, respectively. Complex 3 shows a 2D corrugated polymeric structure constructed by 34-membered macrocycles. Complex 4 adopts a 1D infinite chain structure. Furthermore, in vitro cytotoxicity investigations of complexes 1, 3 and 4 were conducted. Importantly, further cytotoxic assessments of complex 3 against human hepatocellular carcinoma cells (HepG-2) demonstrate that complex 3 could induce an apoptotic retardation effect on proliferation via possible mitochondrial-dependent cross-talk between various signaling proteins and the intracellular p53-Bax-caspases approach should be the major pathway of apoptosis.