Organotin(IV) complexes derived from hydrazone Schiff base: Synthesis, crystal structure, in vitro cytotoxicity and DNA/BSA interactions

Abstract Four new organotin(IV) complexes Me 2 SnL 1 , Ph 2 SnL 1 , Me 2 SnL 2 and Ph 2 SnL 2 (H 2 L 1  = 5-chlorosalicylaldehyde isonicotinoyl hydrazone and H 2 L 2  = 2-hydroxy-4-methoxybenzaldehyde isonicotinoyl hydrazone) have been synthesized and characterized by elemental analyses, FT-IR, NMR ( 1 H, 13 C and 119 Sn) and single crystal X-ray diffraction techniques. The crystal structure analysis shows that complexes 1 and 2 are trinuclear compounds, of which the enolic hydrazone Schiff base ligand chelate to tin center in the ONO tridentate mode. In contrast, the complexes 3 and 4 are uninuclear compounds with the central Sn atoms adopting five-coordinated distorted trigonal bipyramid geometry. Cytotoxicity of the four complexes was studied against two human cancer cell lines (A549 and HeLa) by the MTT assay method. The results demonstrate that the four complexes exhibited good anticancer activity, and mononuclear complex 4 was found to be more effective towards HeLa cancerous cells. The interactions between all complexes with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) were investigated using various spectroscopic techniques. The viscosity measurements, thermal temperature ( T m) and UV–Vis spectra data suggested intercalative binding between DNA and the four organotin (IV) complexes. In addition, all complexes could quench the intrinsic fluorescence of BSA in a static quenching process, which was also confirmed by the docking study.