Synthesis, characterization of copper(II), cobalt(II), nickel(II), zinc(II) and cadmium(II) complexes of [7-hydroxy-4-methyl-8-coumarinyl]glycine and a comparitive study of their microbial activities

A new Mannich base, [7-hydroxy-4-methyl-8-coumarinyl]glycine [MCGH2], has been prepared by the condensation of 7-hydroxy-4-methyl-coumarin with glycine and formaldehyde. Its conformational changes on complexation with transition metal ions [copper(II), cobalt(II), nickel(II), zinc(II) and cadmium(II)] have been studied on the basis of elemental analysis, conductivity measurements, spectral (infrared, 1H NMR, electronic, EPR), magnetic and thermogravimetric studies. The infrared spectral studies of all the complexes reveal that the ligand has coordinated through –NH and two hydroxyl groups. The conductance data of the complexes suggest them to be non-electrolytes. Fluorescence property of the ligand and its metal complexes was studied and concluded that the ligand MCGH2 can be a potential candidate for the determination of zinc(II) and cadmium(II) at room temperature by fluorimetric method. The antimicrobial activity of all the compounds was studied against Gram negative (Escherichia coli) and Gram positive (Bacillus cirroflagellosus) bacteria and fungi, Aspergillus niger and Candida albicans. It was observed that the coordination of metal ion has a pronounced effect on the microbial activities of the ligand. All the metal complexes have shown higher antimicrobial effect than the free ligand.

Graphical abstractThe metal salts, ligand and the corresponding complexes were screened simultaneously for their antimicrobial activity. As a synergic effect the metal complexes have shown enhanced activity against both the bacteria and fungi used.Figure optionsDownload full-size imageDownload as PowerPoint slide