Synthesis, characterization and antimicrobial activity of mixed ligand Cu(II) and Co(II) complexes of beta-diketones with nitrogen-containing ligands

Abstract

Mixed ligand copper(II) and cobalt(II) complexes of benzoylacetone and acetylacetone (BzacH and AcacH) with 2,2′-bipyridine (Bipy) and 1,10-phenanthroline (Phen), and Tetramethylethylenediamine (Tmen) have been synthesized and characterized by conductance measurement, magnetic susceptibility measurement, infrared spectroscopy and electronic spectroscopy. The in vivo antimicrobial screenings of the ligands and complexes were tested for their effect on bacteria and fungi by disc diffusion method. The conductivity measurement in nitromethane indicates that all the mixed ligand complexes are non-electrolytes and are in the range 8.22–50.50 Ω^-1cm²mol^-1. The room temperature magnetic moments suggest that the mixed ligand complexes copper(II) are magnetically dilute having an electron each, while the mixed ligand cobalt(II) complexes are high spin complexes with three unpaired electrons. The electronic absorption spectra of the compounds suggest possible 4-, 5- and 6-coordinate geometries. The infrared spectra showed that there were lower frequency shifts of the carbonyl on complexation. The microbiostatic activities of the complexes revealed that all the complexes showed enhanced activities against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa, but have moderate activity against Candida albicans and Aspergillus niger