Pentacoordinated diorganotin(IV) complexes resulting from tridentate (NOO) donor Schiff bases: Synthesis, characterization,in vitroantioxidant, antimicrobial activities, and QSAR studies

A series of diorganotin(IV) complexes of type R2SnL, (where R = Me, Et, Bu and Ph) were prepared by the reaction of tridentate (NOO) donor Schiff base ligands with diorganotin(IV) dichloride in an equimolar ratio. The products were characterized by various spectroscopic techniques and physical and analytical methods (UV-vis, FTIR, NMR, fluorescence, elemental analysis). Spectroscopic data suggest that the Schiff base acts as a tridentate ligand (NOO) coordinated with a central tin atom via two oxygen and one imine nitrogen atom in a pentacoordinated fashion. The synthesized compounds were assayed for theirin vitroantimicrobial activity against bacterial and fungal strains. All the compounds displayed promising results with the complexes being more potent than free ligands. The antioxidant activity of the compounds was determined by interaction with 2,2-diphenyl-1-picrylhydrazyl free radical. Complex Ph2SnL3(16) was found to have the most potential antimicrobial activity against all tested strains and also exhibited excellent antioxidant activity. Quantitative structure-activity relationship of compounds was studied for antimicrobial activity with molar refractivity indices as significant statistical parameter.