Antibacterial and antifungal oxovanadium(IV) complexes of triazole-derived Schiff bases

Abstract

A newly synthesised series of antibacterial and antifungal triazole-derived Schiff base ligands (L 1 )–(L 5 ) has been prepared by the condensation reaction of 3,5-diamino-1,2,4-triazole with methyl-, chloro- and nitro-substituted thiophene-2-carboxaldehydes in (1:2) molar ratio. The most probable structures of the synthesised Schiff base ligands were established on the basis of their physical, spectral (IR, 1H and 13C NMR and mass spectrometry) and analytical (CHN analysis) data. These Schiff bases potentially act as bidentate ligand and were further made to react with the vanadyl(IV) sulphate (VOSO4·5H2O) in (1:2) (metal:ligand) molar ratio to prepare their oxovanadium(IV) complexes (1)–(5). All oxovanadium(IV) complexes showed a square-pyramidal geometry which was established on the basis of their physical, spectral and analytical data. The Schiff base ligands and their vanadyl(IV) complexes have been screened for their in vitro antibacterial, antifungal and brine shrimp bioassay. The antimicrobial activity data showed the vanadyl(IV) complexes to be more potent antibacterial and antifungal than the parent Schiff bases against one or more bacterial and fungal species.