Five organotin complexes derived from hydroxycinnamic acid ligands: Synthesis, structure, in vitro cytostatic activity and binding interaction with BSA

Five new organotin(IV) hydroxycinnamates, [(Me3Sn)HL1]n (1), [(Ph3Sn)2L1]n (2), (n-Bu2Sn)(HL1)2 (3), [(Me3Sn)HL2]n (4), [(Ph3Sn)2L2]n (5), have been synthesized by the reactions of R3SnCl (R = Me, Ph) or n-Bu2SnO with the corresponding hydroxycinnamic acid proligands [H2L1 = 4-OH-3-CH3OC6H3CH=CHCOOH, ferulic acid; H2L2 = 4-OH-3,5-(CH3O)2C6H2CH=CHCOOH, sinapic acid]. All the complexes have been characterized by X-ray diffraction analysis, elemental analysis, NMR (1H, 13C and 119Sn), FT-IR, and PXRD (Powder X-ray diffraction). The structural analyses reveal that complexes 1, 2 and 5 display 1D infinite zig-zag chain structure, in which the 1D chains are further linked into a 3D supramolecular structure through intermolecular O-H···O interactions (for complex 1) or C-H···O interactions (for complex 5). Complex 3 presents mononuclear tin monomer and further constructs 2D planar supramolecular structure through intermolecular O-H···O interactions. Complex 4 displays 1D right-handed helical chain and further connects into a 3D supramolecular architecture through intermolecular O-H···O interactions. Furthermore, the in vitro cytostatic activity of complexes 1-5 was preliminarily evaluated by MTT method, and the results showed that complexes 2, 3 and 5 exhibited high cytostatic activity. The protein-binding properties of complexes 2, 3 and 5 were also investigated, which indicated these complexes could quench the intrinsic fluorescence of BSA in a static way.