Novel organotin (IV) complexes derived from 4,4′‐oxybisbenzoic acid: synthesis, structure, in vitro cytostatic activity and binding interaction with BSA

Abstract

Six novel organotin (IV) complexes, [(Me3Sn)2(H2O)2L] (1), [(R3Sn)2L]n (R = Me 2, R = n‐Bu 3), [(Ph3Sn)2L] (4), [Me2SnL]n (5), [(Me2Sn)2L(μ3‐O)]n (6) have been designed and synthesized by the reactions of 4,4′‐oxybisbenzoic acid (H2L) and triorganotin (IV) chloride or oxide. All the complexes have been characterized by elemental analysis, FT‐IR, NMR, ESI‐Mass, PXRD and X‐ray crystallography. The single crystal diffraction reveals that complexes 1 and 4 represent dinuclear tin monomers. Complexes 2 and 3 display 2D network structure and 2D corrugated framework respectively, which both contain tetranuclear 36‐membered macrocycles. Furthermore, 2D structures are linked into a 3D supramolecular structures through intermolecular C‐H···π interactions. Complex 5 shows 1D infinite helical chain and further constructs 3D ladder supramolecular architecture through additional Sn···O and C‐H···O intermolecular interactions. Complex 6 displays 1D infinite polymeric chain containing 28‐membered macrocyclic ring. Preliminarily in vitro cytostatic activity studies on cervical carcinoma cell lines (HeLa) and hepatocellular carcinoma cell lines (HepG‐2) by MTT assay for some complexes reveal that complexes 3 and 4 exhibit high cytostatic activity. Further, complexes 3 and 4 were selected to investigate interactions of bovine serum albumin (BSA) by fluorescence quenching spectra and synchronous fluorescence spectra, which indicates that the complexes could quench the intrinsic fluorescence of BSA in a static quenching process.