Novel organotin complexes derived from 2,2′-selenodiacetic acid: synthesis and biological evaluation

The reactions of 2,2'-selenodiacetic acid and the corresponding organotin(IV) chloride with sodiumethoxide in ethanol, or via a solvothermal synthetic route, have afforded four organotin polymers, namely, [(Me3Sn)(2)Se(CH2COO)(2)](n) (1), [(Me2Sn)(2)Se(CH2COO)(2)(mu(3)-O)](n) (2), [(Bu3Sn)(2)Se(CH2COO)(2)](n) (3), and [(Bu2Sn)Se(CH2COO)(2)](n) (4). All the complexes were fully characterized by elemental analysis, FT-IR, NMR (H-1, C-13, and Sn-119) spectroscopy and single crystal X-ray diffraction analysis. The structural analysis reveals that complex 1 is a 2D-polymer containing interconnected 24-membered (Sn4O8C10Se2) macrocyclic rings. Unlike complex 1, the 2D polymer structure of complex 2 is made up of the typical ladder tetraorganodistannoxane unit containing 32-membered (Sn4O8C16Se4) macrocyclic rings. Complex 3 is a 3D corrugated polymeric structure in which the deprotonated dicarboxylic acid acts as a tetradentate ligand by four oxygen atoms. Complex 4 is a 1D zigzag coordination polymer and the tin coordination geometry is described as skewed-trapezoidal bipyramidal. In particular, preliminary cytotoxic assessments of the involvement of complex 4 in the apoptotic death of MDA cells were conducted, and the results revealed that the antiproliferative and proapoptotic effect of complex 4 in MDA cells prominently contributed to the overload of intracellular ROS levels and the dysfunctional depolarization of mitochondrial membranes.