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In this work, we were interested in the search for new catalysts for catecholase, whose principle is based on the oxidation reaction of catechol to o-quinone. In this context, a series of ligands derived from 2-phenylimidazo[1,2-a]pyridine-3-carbaldehy were synthesized; then, the complexes formed in situ between these ligands and copper(II) salts, namely Cu(CH3COO)2, CuSO4, Cu(NO3)2and CuCl2were examined for their catecholase activity. The kinetics of the reaction was followed by measuring the absorbance versus time with a UV-Vis spectrophotometer for one hour. Compared with other work done in the same framework, the results obtained in this study show that the copper(II)-ligand complexes studied possess excellent catalytic activities for the oxidation of catechol to o-quinone. In particular, the complexes formed between the ligands and the salts Cu(CH3COO)2and CuSO4show oxidation rates much higher than those found in the literature. On the other hand, the complexes formed between the ligands and Cu(NO3)2and CuCl2also catalyze the reaction, but with much lower oxidation rates than the former. The complex formed between Cu(CH3COO)2and L1(2-phenylimidazo[1,2-a]pyridine-3-carbaldehyde) shows the highest catalytic activity with an oxidation rate of 260.41 µmol L−1s−1, and the complex formed between L6(6-chloro-2-(4-chlorophenyl)imidazo[1,2-a]pyridine-3-carbaldehyde) and CuCl2shows the lowest catalytic activity (43.4 µmol L−1s−1). This study’s results also show that these complexes’ oxidation efficiency depends on several factors, namely the nature of the substituents on the ligands and the anions of the copper salts.

New excellent catalysts for the oxidation of catechol to o-quinone were developed in this study by the combination of some benzodiazepine derivatives ligands with copper(II) salts such as Cu(CH3COO)2, CuSO4, Cu(NO3)2and CuCl2at ambient conditions. The study has shown that the in-situ generated copper(II) complexes of the ligands used are excellent models for reproducing the enzymatic activity of catechol oxidase. The rates of this oxidation vary from 127 µmol.L− 1.s− 1for the complex formed by ligand L3(1-benzyl-4-phenyl-1,5-benzodiazepine-2-one) and the metal salt CuCl2to 424.47 µmol.L− 1. s− 1for the complex formed by ligand L1(4-phenyl-1,5-benzodiazepin-2-one) and the metal salt Cu(CH3COO)2who shows the best catalytic activity. Also, this work demonstrates that the rate of oxidation depends on different parameters such as the nature of the ligand and the ionic salts. The combination ligand/[Cu (CH3COO)2] leads to the fastest catalytic process.