Development of new tridentate ligands bearing hydrazone motif and their diorganotin(IV) complexes: Synthesis, spectral, antimicrobial and molecular docking studies

Abstract

Current antimicrobial drug discovery and advancement attempts are aimed to identify new complexes that can work effectively against the infections caused by microbes. The aim of present study was to synthesize new diorganotin(IV) complexes of N'-((8-hydroxy-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)methylene)-2-nitrobenzohydrazide (H2L1), N'-((8-hydroxy-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)methylene)-3-methoxybenzohydrazide (H2L2) and N'-((8-hydroxy-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)methylene)-4-methylbenzohydrazide (H2L3) Schiff base ligands with formula R2SnL1−3 (where R = Me, Et, Bu and Ph). Various spectral and physico-analytical techniques such as elemental analysis, FT-IR, multinuclear (1H, 13C, 119Sn) NMR, HRMS and XRD were utilized to structurally elucidate the prepared compounds. Based on the spectral data, it was concluded that ligands behave in a tridentate manner and coordinates to the central tin atom through ONO donor atoms. Furthermore, the synthesized compounds were examined for in vitro antimicrobial activity against four bacterial and two fungal strains. Among the examined compounds, Ph2SnL1 complex (MIC = 0.0095 µmol/mL) was found to be the most active. To rationalize the preferred mode of interactions of the most active compound, a molecular docking study of compound Ph2SnL1 was executed in the binding site of 3-oxoacyl-[acyl-carrier-protein] synthase 2 (FabF) of E. coli and sterol 14-alpha demethylase of C. albicans. Compound Ph2SnL1 inhibits the microbes effectively and it could be an effective and new candidate for the modulation of various infections. New diorganotin(IV) complexes (4–15) were prepared from tridentate Schiff base hydrazones (1–3). The compounds were examined for in vitro antimicrobial activity. Further, molecular docking study of the most potent compound Ph2SnL1 (7) was performed against the enzyme 3-oxoacyl-[acyl-carrier-protein] synthase 2 (FabF) of E. coli and sterol 14-alpha demethylase of C. albicans.