Dinuclear Copper(II) Complexes of 2,6-Bis[(N-Methylpiperazine-1-yl)methyl]-4-Formyl Phenol Ligand: Promising Biomimetic Catalysts for Dye Residue Degradation and Drug Synthesis

In this study, three dinuclear copper(II) complexes of ligand 2,6-bis[(<i>N</i>-methyl-piperazine-1-yl)methyl]-4-formyl phenol (L1) and one of 2,6-bis[(<i>N</i>-methylpiperazine-1-yl)methyl]-4-formyl phenol dimethylacetal (L2) with copper(II) ions have been investigated as new types of biomimetic catalysts for the oxidative transformation of different aminophenols and phenyldiamines. All the complexes of interest were newly synthesized and further characterized by IR spectroscopy, UV-Vis and mass spectrometry, X-ray diffraction, and selected electrochemical measurements. Crystal structures of these dinuclear copper(II) complexes have revealed that the coordination-shell geometry of copper atoms is close to a tetragonal pyramid. Catecholase, phenoxazinone synthase, and horseradish peroxidase-like activities were observed in pure methanol and water-methanol mixtures in the presence of molecular oxygen. The potential applicability of the complexes under study is discussed with respect to their possibilities and limitations in the replacement of natural copper-containing oxidoreductases in the oxidative degradation of water-insoluble chlorinated aminophenols in the dye industry or in the production of phenoxazine-based drugs.