Synthesis, characterization, in vitro antimicrobial, DNA binding activity and QSAR studies of diorganotin(IV) complexes of Schiff bases derived from 2-benzoyl-1H-indene-1,3(2H)-dione and 4-substituted benzoic acid hydrazides

Abstract

A series of new diorganotin(IV) complexes of the type [R′2SnL] have been synthesized by the reaction of 2-benzoyl-1H-indene-1,3(2H)-dione Schiff bases with R′2SnCl2, (R′ = Me, Et, n-Bu, Ph) in 1:1 molar ratio. These complexes were well characterized by IR, 1H, 13C, 119Sn NMR, XRD and mass spectrometry techniques. In the search for biologically more effective antimicrobial agents, all the synthesized ligands and organotin complexes were evaluated for their in vitro antimicrobial activities against two Gram-positive and two Gram-negative bacteria, and three fungal strains by serial dilution method. The results of spectral data revealed that the complexes formed were pentacoordinated with tridentate ligands which coordinated through azomethine N and carbonyl O and carboxylate O to the central tin atom. The ligands on coordination with tin metal showed a discernible augmentation in biocidal activity, however, the Ph and Bu complexes were found to be more intoxicating. The results revealed that the synthesized complexes were more noxious toward Gram-positive strains as compared to Gram-negative strains which may be attributed to the presence of an outer lipid membrane of lipopolysaccharides. Further, QSAR studies and DNA binding studies were performed which supported that bioactivity gets enhanced on complexation.