Copper(II) complex of new non-innocent O-aminophenol-based ligand as biomimetic model for galactose oxidase enzyme in aerobic oxidation of alcohols

Mononuclear copper(II) complex of tetra-dentate o-aminophenol-based ligand (H2LBAPP) has been synthesized and characterized. The three dentate precursor (HLBAP) of the final ligand was synthesized first, while the title four-dentate copper bound ligand was synthesized in situ, isolated only in the final copper species [CuLBAPP]. This copper coordination complex reveals a distorted square-planar geometry around the copper(II) centre by one oxygen and three nitrogen atoms from the coordinating ligand. The ligand is thus twice deprotonated via hydroxy and amine groups. The complex is red, non-typical for copper(II), but.the effective magnetic moment of 1.86 B M. and a single isotropic symmetry EPR signal with g 2.059 confirm a S = 1/2 diluted spin system, without copper-copper magnetic coupling. Electrochemical oxidation of this complex yields the corresponding Cu(II) phenyl radical species. Finally, the title complex CuLBAPP has shown good and selective catalytic activity towards alcohol to aldehyde oxidation, at aerobic room temperature conditions, for a set of different alcohols. (C) 2016 Elsevier B.V. All rights reserved.