Original Articles: 2010 Vol: 2 Issue: 6
Microwave synthesis, spectroscopic, thermal and biological significance of some transition metal complexes containing heterocyclic ligands
Some new Schiff base complexes of Cr(III), Co(II), Ni(II) and Cu(II) derived from 5- bromosalicylaldehyde with 2-amino-5-nitrothiazole ( L 1 H) and 4-dimethylaminobenzaldehyde with 2-amino-3-hydroxypyridine (L 2 H) have been synthesized by conventional as well as microwave methods. These compounds have been charac terized by elemental analysis, FT-IR, FAB-mass, molar conductance, electronic spectra, 1 H-NMR, ESR, magnetic susceptibility, thermal, 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. The 1 H-NMR spectral data indicates that the phenolic protons have been displaced during complex ation. FAB-mass and thermal data show degradation pattern of the complexes. The thermal b ehaviour of metal complexes shows that the hydrated complexes loses water molecules o f hydration in the first step; followed by decomposition of ligand molecules in th e subsequent step. The Schiff base and metal complexes show a good activity against th e Gram-positive bacteria; Staphylococcus aureus and Gram-negative bacteria; Escherichia coli and fungi Aspergillus niger and Candida albicans. The antimicrobial results also indicate t hat the metal complexes are better antimicrobial agents as compared to the Schiff base s.