Synthesis, structural elucidation and anticancer activity of diorganotin(IV) complexes derived from isonicotinoyl hydrazones

Herein, two Schiff base ligands N-(4-diethylamino-2-hydroxybenzylidene) isonicotinohydrazide (L1) and N-(2,3- dihydroxybenzylidene) isonicotinohydrazide (L2) and their six di-organotin(IV) complexes (R = C4H9 (1, 4), C6H5 (2, 5) and CH3 (3, 6)) were synthesized. The solid state and solution chemistry of the ligands and their organotin(IV) complexes was explored through single crystal XRD, FTIR and NMR (1H, 13C and 119Sn) spectroscopy. The single crystal XRD analysis was carried out for complexes 1, 2 and 5, reveals the presence square pyramidal, trigonal bipyramidal and pentagonal bipyramidal geometries, respectively. All structures showed distorted geometries because of the constraint offered by five and six membered chelate rings. The results obtained from the interaction study of ligands and complexes with SS-DNA were indicative of high binding potential through a spontaneous process. The results of in vitro antimicrobial studies validated the well-known theory of chelation and overtone concept. Anticancer activities conducted for the ligands and complexes revealed evident anti-proliferative activity of 1, 2, 4 and 5 complexes. Complex 2 being the most active one, exhibited proapoptotic, cytotoxic effect after PI and DAPI stains. Moreover, after H2DCF-DA staining the treated cancerous cells, an induced oxidative stress was detected. Complexes 2 and 4 also revealed the activation of mitochondrial pathway of apoptosis in treated cancer cells.