Syntheses, structural characterization, in vitro cytotoxicities and DNA-binding properties of triphenylantimony di(N-oxy phthalimide) and di(N-oxy succinimide) complexes

Triphenylantimony di(N-oxy phthalimide) and triphenylantimony di(N-oxy succinimide) compounds, [(C6H4C2O2NO)2Sb(C6H5)3] (1) and [(C2H4C2O2NO)2Sb(C6H5)3] (2), have been synthesized by the reactions of corresponding ligands (N-oxy phthalimide and N-oxy succinimide) with triphenylantimony(V) dichloride in 2:1 stoichiometries. Two compounds were characterized using spectroscopic (IR, 1H and 13C NMR, and UV–vis) and single crystal X-ray diffraction techniques. Crystal structures show all compounds exhibit five-coordinate trigonal bipyramid geometry, binding with three phenyl groups and the deprotonated organic ligands. Intermolecular H-bonding found in 1 and 2 contribute to the crystal stability and compactness. In vitro cytotoxicities of 1 and 2 were evaluated by colorimetric MTT assay in four cisplatin-resistant human cancer cell lines: A549, HT-29, HCT-116 and HL-60 cell lines, and the structure–activity relationships were drawn. It was found that both compounds exhibit higher in vitro cytotoxicities than cisplatin to the four cell lines, making them promising anticancer agents in drug resistant cell lines. Furthermore, DNA-binding properties of 1 and 2 with calf thymus DNA (ct-DNA) were investigated by fluorescence spectra. The emission from ethidium bromide (EB) bound DNA decreases by increasing the concentration of compounds, and studies reveal that compound 1 exhibited higher DNA-binding ability than 2.