Oxime derivative unsymmetrical azine and its complexes: Synthesis, spectroscopy and catecholase activity

1-[(Z)-{(2E)-[(3E)-3-(hydroxyimino)butan- ylidene]hydrazinylidene}methyl]naphthalen -2-ol, H2L (3) was synthesized by the agents of 2-hydroxy-1-naphtaldehyde, 2,3-butanedione monoxime and hydrazine in two steps. Characterization of the ligand and its mononuclear Ni(II), Cu(II) and Zn(II) complexes was made by IR, 1H- and 13C NMR, UV–vis, X-ray, mass spectra (ESI and TOF), molar conductivities and magnetic susceptibility measurements. The ligand has potentially two nitrogen and an oxygen to be able to bind a metal center. In the light of analytical and physical results, it was suggested that the ligand coordinate to by N,O/N2/N2O donor set to form square planar, octahedral, distorted square planar and tetrahedral complexes. Molar conductivity measurements reveal that all the complexes are non-electrolytes. In addition, catecholase activities of the complexes were studied. However, the only one of the complexes, 3b behaves as an effective catalyst towards oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) to its corresponding quinone derivative in MeOH saturated with O2. The reaction follows Michaelis–Menten enzymatic reaction kinetics with turnover numbers (kcat) 1.19×103 h-1. Keywords: Oxime, Metal complex, Synthesis, Characterization, Catecholase activity.