Synthesis and physico-chemical studies of metal(II) complexes with diacetyl benzaldehyde acyldihydrazones and their bio-activity

Complexes of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with diacetyl benzaldehyde oxalic acid dihydrazone (dbodh), CH₃COC(CH₃)=NNHCOCONHN=CHC₆H₅ and diacetyl benzaldehyde malonic acid dihydrazone (dbmdh), CH₃COC(CH₃)=NNHCOCH₂CONHN=CHC₆H₅ of general composition [M(dbodh)Cl]Cl and [M(dbmdh)Cl]Cl were synthesized and characterized by microanalyses, molar conductance, magnetic susceptibility, UV–Vis, ESR and IR spectra and X-ray diffraction studies. The complexes are 1 : 1 electrolytes in DMF and are insoluble in water and common organic solvents. The dbodh and dbmdh are neutral tridentate ligands in most complexes and coordinate via one >C=O and two >C=N–groups. In Cu(II) complexes the ligands are pentadentate coordinating through three >C=O and two >C=N–groups. The magnetic moment values and UV–Vis spectra suggest square-planar geometry for Co(II) and Ni(II) complexes and distorted octahedron for both Cu(II) complexes. The ESR spectra of Cu(II) complexes show well-defined copper hyperfine lines in DMSO solution at 120 K and exhibit d _{x ² ?y ²} as the ground state. The X-ray diffraction parameters for [Ni(dbodh)Cl]Cl and [Co(dbmdh)Cl]Cl correspond to a tetragonal crystal lattice. The complexes show significant antifungal activity against Alternaria sp., Curvularia sp. and Colletotrichum sp. and fair antibacterial activity against Bacillus subtilis and Pseudomonas fluorescence.