Synthesis, spectral studies and in vitro antimicrobial activity of some new di-/tri-organotin(IV) complexes of Schiff bases derived from 2-benzoylpyridine

Abstract

In the present work, a series of twenty-four organotin(IV) complexes of the type [R2SnClL, R3SnL] were synthesized by the condensation of 2-benzoylpyridine Schiff bases with R2SnCl2, R3SnCl (R = Me, n-Bu or Ph) in 1:1 mole ratio. These complexes were well characterized by IR, 1H-, and 13C-, 119Sn-NMR, XRD and mass spectral 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 two fungal strains by the serial dilution method. The results of spectral data revealed that the formed complexes were hexacoordinated with tridentate ligands coordinated through azomethine N, pyridine N and carboxylate O ligation sites. 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 towards Gram-positive strains as compared to Gram-negative strains, which may be attributed to the presence of the outer lipid membrane of lipopolysaccharides.