Synthesis and structures of polynuclear organotin(IV) complexes of a polyaromatic carboxylate ligand and cytotoxic evaluation in tumor cell lines

Three polynuclear organotin(IV) derivatives of composition [n-Bu3Sn(HL)]n 1 , [Ph3Sn(HL)]n 2 and [n-Bu2Sn(HL)2]2 3 were synthesized by reacting 2-((E)-(4-hydroxy-3-((E)-((4-(methoxycarbonyl)phenyl)imino)methyl)phenyl)diazenyl)benzoic acid (H'HL) with (n-Bu3Sn)2O, Ph3SnOH and n-Bu2SnO, respectively. The structures 1 -3 were fully characterized by elemental analysis, IR and NMR ( 1 H, 13 C, and 119Sn), 119Sn Mossbauer spectroscopy, and additionally, the molecular and crystal structures of 1 -3 and its pro-ligand (H'HL) were established by single-crystal X-ray diffraction analysis. The tributyltin(IV) complex 1 is a one-dimensional coordination polymer, in which the azo ligand bridges adjacent Sn(IV) centres solely via the two carboxylate O-atoms. The hydroxy H atom forms an intramolecular O-H ...N hydrogen bond with the imine N-atom, as observed in the crystal structure of H'HL. The triphenyltin(IV) complex 2 is also a one-dimensional coordination polymer, but in this case the azo ligand bridges adjacent Sn(IV) centres via its carboxylate group and the deprotonated phenol O-atom. Unlike in 1, the phenol H-atom has migrated to the imine N-atom, to give a zwitterionic form of the azo ligand. The tin centers in 1 and 2 are pentacoordinated and reveal a distorted trans-R3SnO2 trigonal-bipyramidal environment. The dibutyltin(IV) complex 3 crystallizes as discrete centrosymmetric dinuclear entities where the unique Sn(IV) center is heptacoordinated in a distorted pentagonal bipyra-mid coordination geometry. In vitro cytotoxicity studies of compound 1 were performed and compared with 2 across a panel of human tumor cell lines and the results were compared with the data of six clinically used anticancer drugs.

Automated summary

Three polynuclear organotin(IV) derivatives, denoted as [n-Bu3Sn(HL)]n 1, [Ph3Sn(HL)]n 2, and [n-Bu2Sn(HL)2]2 3, have been successfully synthesized by reacting 2-((E)-(4-hydroxy-3-((E)-((4-(methoxycarbonyl)phenyl)imino)methyl)phenyl)diazenyl)benzoic acid (H'HL) with (n-Bu3Sn)2O, Ph3SnOH, and n-Bu2SnO, respectively. The structures of 1-3 were fully characterized and their molecular and crystal structures were determined by single-crystal X-ray diffraction analysis. Compound 1 is a one-dimensional coordination polymer, whereas compound 2 is a one-dimensional coordination polymer with a zwitterionic form of the azo ligand. Compound 3 crystallizes as discrete centrosymmetric dinuclear entities with a heptacoordinated Sn(IV) center in a distorted pentagonal bipyramidal coordination geometry.