Synthesis, crystal structure, and anticancer activity of organotin(IV) complexes based on chlorine substituted aryl ligands

Three series of (dimethyl-, dibutyl-, and diphenyl-) new organotin(IV) complexes based on chlorine substituted aryl ligands were synthesized and characterized by UV, 1H NMR, 13C NMR, 119 Sn NMR, HRMS, and X-ray crystallography analysis. MTT results showed that chlorine substitution at different positions on the aryl group exhibited different anticancer activities. Among them, 5-chloro substituents > 3,5-dichloro substituents > 3-chloro substituents on the aryl ring of salicylaldehyde on Schiff base ligand. In addition, different substituents on the tin atom also demonstrated extreme differences in anticancer activities, where dibutyltin > diphenyltin > dimethyltin. Interestingly, the complex LTDB2 exhibited excellent anti-proliferative activity against breast cancer MDA-MB-231 cells (superior to cisplatin) and lower toxicity against human embryonic kidney HEK-293 cells in vitro. Flow cytometry showed that LTDB2 not only induced apoptosis, but also induced cell cycle arrest in G2 phase. These findings provide new insights for further research and development of novel organotin(IV) complexes as anticancer drugs.