Catecholase activity investigations using in situ copper complexes with pyrazole and pyridine based ligands

The in situ copper (II) complexes of six pyrazole and pyridine based ligands: 1-[5-methyl-1-pyridin-2-yl-1H-pyrazol-3-yl] methanol L1, 2-(3,5-dimethyl-pyrazol-1-yl)-pyridine L2, (5-methyl-3-pyridin-2-yl-1H-pyrazol-1-yl) ethyl acetate L3, 1′,5,5′-trimethyl-1′H-1,3′-bipyrazol-3-ethyl carboxylat L4, (1′,5,5′-trimethyl-1′H-1,3′-bipyrazol-3-yl) methanol L5, and 5,5′-diphenyl-3,3′-bipyrazole L6, are reported and studied for their catecholase activities at ambient conditions, the reaction rate depends on four parameters: The nature of the carbonic chain bounded to the pyrazole ring, the nature of counter anion, the concentration of ligand and the nature of solvent. The highest rate activity is given by complex resulting from one equivalent of ligand L4 and two equivalents of Cu(CH3COO)2 in methanol, which equal to 4.440 μmol L−1 min−1.

Figure optionsDownload high-quality image (63 K)Download as PowerPoint slideHighlights
► All copper complexes formed in situ catalyze the oxidation reaction of catechol.
► Oxidation reaction rate depends on four parameters.
► The highest rate activity is given by L4 [Cu(CH3COO)2].