Synthesis, spectral studies and antibacterial activity of Cu(II), Co(II) and Ni(II) complexes of 1-(2-hydroxyphenyl)-3-phenyl-2-propen-1-one, N2-[(3,5-dimethyl-1H-pyrazol- -1-yl)methyl]hydrazone

A new series of Cu(II), Co(II) and Ni(II) complexes with the 1-(2- -hydroxyphenyl)-3-phenyl-2-propen-1-one, N 2 -((3,5-dimethyl-1H-pyrazol-1- -yl)methyl)hydrazone ligand, C21H22N4O (LH), were synthesized by the reaction of 1-(2-hydroxyphenyl)-3-phenyl-2-propen-1-one, hydrazone with (3,5-dime- thyl-1H-pyrazol-1-yl)methanol and characterized. The nature of the bonding and geometry of the complexes were deduced from elemental analysis, IR, electronic and 1 H-NMR spectroscopy, and magnetic susceptibility and conductivity measurements. The studies indicated square-planar, tetrahedral and octahedral geometry for the copper(II), cobalt(II) and nickel(II) complexes, respectively. The ESR spectra of the copper(II) complex in acetonitrile at 300 and 77 K were recorded and their salient features are reported. The electro- chemical behavior of the copper (II) complex was studied by cyclic voltam- metry. The antimicrobial activity of the ligand and its metal complexes were studied against the following strains of microorganism: Staphylococcus aureus, Salmonella enterica typhi, Escherichia coli and Bacillus subtilis by the well diffusion method. Metal complexes showed enhanced antimicrobial activity compared with that of the free ligand.