Dinuclear heptacoordinate dibutyltin (IV) complexes derived from Schiff bases and dicarboxylates: Synthesis, cytotoxicity, and antioxidant activity

The synthesis of dinuclear dibutyltin (IV) complexes 1a–4d, prepared in one pot by the reaction of 2-amino-4-R-phenol (R = H, Me, Cl, NO2), 2-pyridinecarboxaldehyde, dicarboxylic (2,5-pyridinedicarboxylic, terephthalic, isophthalic, and oxalic) acids and dibutyltin oxides, is described. The complexes were characterized using IR, MS and 1H, 13C and 119Sn NMR techniques. The molecular structures of complexes 1a, 1c and 4c were established using X-Ray diffraction, and these complexes exhibited a distorted pentagonal-bipyramidal (BPT) geometry in which the equatorial plane consisted of three oxygen atoms and two nitrogen atoms, and the butyl groups occupied the axial positions. The cytotoxicity of the terephthalic acid derivatives 1a–d in HCT-15 colon cancer, MCF7 breast cancer and PC3 prostate cancer cell lines was investigated in vitro. The antioxidant activity of these complexes was also measured using the DPPH (1,1-diphenyl-2-picrylhydrazyl) assay.