Novel triorganotin complexes based on phosphonic acid ligands: Syntheses, structures and in vitro cytostatic activity.

Six novel organotin phosphonate complexes, [(MeSn)(HL)]1, [(MeSn)(HL)]2, [(MeSn)L(HO)]3, [(PhSn)(HL)]4, [(PhSn)L]5 and [(PhSn)L]6, derived from phosphonic acid ligands [NaHL = 1-CHOPO(OH)Na, HL = 1-CHPO(OH), HL = 2-CHPO(OH)], have been synthesized and characterized by elemental analysis, FT-IR, NMR (H, C, P and Sn) spectroscopy and X-ray crystallography. The structural analysis reveals that complexes 1 and 5 display 1D infinite zig-zag chain structures, and complex 2 shows 1D right-handed helical chain structure, while complex 3 displays 1D left-handed helical chain structure. Complexes 4 and 6 are 24-membered macrocyclic rings interconnected by P, O and Sn atoms. Additionally, the molecules of complexes 1 and 3 are further linked through intermolecular π···π and O-H···O interaction into supramolecular structures, respectively. Furthermore, we preliminarily estimated in vitro cytostatic activity of complexes 1-6 against the human cervix tumor cells (HeLa), human hepatocellular carcinoma cells (HepG-2) and human normal breast cells (HBL-100). Importantly, the anti-proliferative properties and possible pathway of complex 6 are investigated, and the results demonstrate that complex 6 could induce apoptotic cell death via an overload of intracellular reactive oxygen species (ROS) levels and the dysfunctional depolarization of mitochondrial membranes.