Studies on Schiff Base Complexes of beta-Diketones/Beta-Ketoesters with 2,4-Dinitrophenylhydrazone and Their Antimicrobial Activities

2,4-Dinitrophenylhydrazone derivatives of Cu(II), Co(II) and Ni(II) complexes have been synthesized. The structural features of the complexes have been confirmed by microanalytical data, IR,UV-Vis, EPR, CV, TGAand powderXRDtechniques. The electronic absorption spectra and magnetic susceptibility indicate a square-planar geometry for copper and tetrahedral for cobalt and nickel complexes. The neutral nature of the complexes is characterized by their low molar conductance. The cyclic voltammogram of copper complex in DMSO solution shows a quasi-reversible peak. The EPR spectrum of copper complex in DMSO at 300 K and 77 K was recorded and its salient features are reported. The antimicrobial activity of the complexes has been extensively studied on microorganisms such as Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa and the fungi Aspergillus niger and Rhizoctonia bataicola by well-diffusion technique using pyridine as solvent. The values of zone of inhibition were found out at 37°C for a period of 24 h. It has been found that all the product complexes have a higher activity than the parent complexes and the standard.