Microwave synthesis, spectral, thermal, 3D molecular modeling analysis and antimicrobial activities of some transition metal complexes of Schiff bases derived from 5-bromosalicylaldehyde

Abstract

The coordination complexes of Cr(III), Co(II), Ni(II) and Cu(II) derived from 5-bromosalicylidene-2-chloro-4-nitroaniline (HL1) and 5-bromosalicylidene-2-amino-5-chlorobenzophenone (HL2) have been synthesized by conventional as well as microwave methods. These compounds have been characterized by elemental analysis, FT-IR, FAB-mass, molar conductance, electronic spectra, 1H-NMR, ESR, magnetic susceptibility, electrical conductivity and thermal analyses. FAB-mass and thermal data show degradation pattern of the complexes. The thermal behavior of metal complexes shows that the hydrated complexes lose water molecules of hydration in the first step; followed by decomposition of ligand molecules in the subsequent steps. The computational studies of Cu(II) complex of 5-bromosalicylidene-2-chloro-4-nitroaniline have also been done. Solid state electrical conductivity studies reflect the semiconducting nature of the complexes. The Schiff base and metal complexes show a good activity against the Gram-positive bacterium; Staphylococcus aureus and Gram-negative bacterium; Escherichia coli and fungi Aspergillus niger and Candida albicans.