Novel organotin complexes containing the 2,2′-bipyridine-3,3′,6,6′-tetracarboxylate. Helical supramolecular structure and cytostatic activity

•Structure of new [(DMF)SnBu2{C10H4N2(COO)4}(SnBu3)2]n·3D helical polymer.•X-ray structures and DFT calculation reveal diverse coordination modes of bptc ligand.•High cytostatic activity of the tin complexes, up to 1000-fold higher than cisplatin.

Reaction between 2,2′-bipyridine-3,3′,6,6′-tetracarboxylic acid (bptcH4) (1) and [Sn2Bu6O] in mild conditions proceeds with Sn-Bu bond cleavage giving polynuclear compounds. Complexes [(H2O)SnBu2(bptc)Sn2Bu6]·H2O (2), [(CH3OH)SnBu2(bptc)Sn2Bu6]·H2O (2a), [(DMF)SnBu2(bptc)Sn2Bu6] (2b) and [(DMF)SnBu2(bptc)Sn2Bu6]·0.5DMF·0.5H2O (3) were characterized using IR, NMR and ESI-MS spectroscopies. The X-ray structures of 1·H2O and (3) have been determined. Compound (3) is an exceptional polymer with seven-coordinate and five-coordinate Sn atoms. The Sn atoms are connected via screw-shaped C10H4N2(COO)4 bridges giving 3D helical network. The NMR and ESI-MS spectra reveal, that complexes in solutions dissociate giving mainly dinuclear complexes. Complex 2 interacts with adenosine 5′-monophosphate (AMP) via phosphate group. Compounds (2), (2a) and (2b) are very effective cytostatic agents against C-32, SNB-19, SH-4 and Colo-829 tumor cells.

Graphical abstractReaction of 2,2′-bipyridine-3,3′,6,6′-tetracarboxylic acid (bptcH4) with [Sn2Bu6O] proceeds with cleavage of Sn–C bond giving polynuclear complexes. The [(DMF)SnBu2(bptc)Sn2Bu6]n·0.5nDMF·0.5nH2O is exceptional 3D helical polymer. The Sn compounds with bptc are very active cytostatic agents.Figure optionsDownload full-size imageDownload as PowerPoint slide