Biological activity studies on some transition metal complexes containing thiazole moiety. Microwave synthesis, spectral, thermal characterization and computational modeling

摘要

Some new Schiff base metal complexes of Cr(III), Co(II), Ni(II) and Cu(II) derived from 5- bromosalicylidene-2-amino-5-methylthiazole (HL1) and 2-hydroxy-1-naphthylidene-2-amino- 5-nitrothiazole (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, thermal, cyclic voltammetry, electrical conductivity and XRD analysis. The complexes exhibit coordination number 4 or 6. The complexes are coloured and stable in air. Analytical data revealed that all the complexes exhibited 1:2 (metal: ligand) ratio. IR data shows that the ligand coordinates with the metal ions in a bidentate manner through the phenolic oxygen and azomethine nitrogen. 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 Schiff base and metal complexes show a good activity against the Gram-positive bacteria; Staphylococcus aureus and Gram-negative bacteria; Escherichia coli and fungi Aspergillus niger and Candida albicans. The antimicrobial results also indicate that the metal complexes are better antimicrobial agents as compared to the Schiff bases.