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Ni(II) and Zn(II) metal complexes with Schiff base derived from Citral and Valine are synthesised and characterized on the basis of spectroscopic techniques (FT-IR, and UV-Visible) and magnetic susceptibility studies The IR spectral data indicated that the Schiff base coordinated to central Ni(II) and Zn(II) ions in a bridged-tridentate and bidentate fashion respectively. Magnetic moment and spectral studies suggest distorted octahedral around the Ni(II) ion and tetrahedral geomtry around Zn(II) ion. The preliminary antimicrobial activity has been evaluated against two Gram-negative bacteria; namely, Pseudomonas aeroginosa and Escherichia coli, one gram-positive bacteria Staphylococcus aureus, and antifungal activity are tested against Aspergillus sps and Candida albicans using disc diffusion method. The result revealed that Ni(II) complex exhibited potent activity when compared to Zn(II) complex and Schiff base.

A new series of [M(L)Y]X·nH2O (M = Co(II) and Cu(II), where Y = H2O, X= NO3 –, n = 3), M = Ni(II), where Y = H2O, X = NO3 –, n = 2) complexes with new Schiff base ligand (L) were synthesized by the condensation of citral and L-histidine. The ligand and its M(II) complexes were characterized based on elemental analysis, spectroscopic studies like FT-IR, electronic, 1H NMR, 13C NMR, ESR data, also accompanied with thermal studies, magnetic susceptibility and molar conductance measurements. In the light of these results, distorted square planar geometry were proposed for the M(II) complexes in which the M(II) centres are present in NNO coordination sphere. To evaluate the biological properties of the Schiff base ligand ( L) and its metal complexes, they were screened for their antibacterial and antifungal activities and the results indicate that the complexes exhibit the significant activity.