Butyltin(IV) 5-sulfosalicylates: Structural characterization and their cytostatic activity

Butyltin complexes with 5-sulfosalicylic acid (H3ssal) [Sn(C4H9)3{O3SC6H3(OH)COOH}] (1), [Sn2(C4H9)6(OOCC6H3OHSO3)] (2) and [Sn3(C4H9)6(OOCC6H3(OH)SO3)2O] (3) have been synthesized and characterized by ESI-MS, IR and 1H, 13C and 119Sn NMR spectra. Their structures and properties in solid state and solutions were proposed on the basis of the spectroscopic data and density functional theory (DFT) calculations at B3LYP/3-21G∗∗ level. The complex 1 in solid state is a chain compound with bridging ligand O3SC6H3(OH)COOH− coordinated to two adjacent SnBu3 units via SO3 and COOH groups and complex 2 is a dinuclear compound with O3SC6H3(OH)COO2− bridging ligand bound to the SnBu3 moieties through SO3 and COO groups. The spectroscopic data indicate that 3 is probably a trinuclear complex containing bridging oxido and Hssal ligands containing two five-coordinate and one six-coordinate tin atoms. The complexes effectively interact with ATP and DAMP nucleotides forming Sn–OP bonds and O′–H′…O and N…H–O (nucleotide–Hssal) hydrogen bonds. All compounds are very effective cytotoxic agents against tumor cells. The cytotoxic activity changes in the order 2 > 1 > 3. Their activity toward non-tumor NHDF cells is much lower. They show also antibacterial and antifungal activity.

Graphical abstractTributyltin and dibutyltin 5-sulfosalicylates showing very high cytotoxic activity against tumor cells have been characterized using spectroscopic methods and DFT calculations. They are very promising antitumor agents because their cytotoxic activity against non-tumor cells is much less. The complexes showed also very high activity against Gram-positive bacteria.Figure optionsDownload full-size imageDownload as PowerPoint slide