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Catechol oxidase activity of dinuclear copper(II) complexes of Robson type macrocyclic ligands: Syntheses, X-ray crystal structure, spectroscopic characterization of the adducts and kinetic studies
Published in Elsevier BV
2009
Volume: 310
   
Issue: 1-2
Pages: 34 - 41
Abstract

Five dinuclear copper(II) complexes, [Cu2L1(N3)2·2H2O] (1), [Cu2L2(N3)2·2H2O] (2), [Cu2L3(N3)2·2H2O] (3), [Cu2L4(N3)2·2H2O] (4) and [Cu2L5(N3)2·2H2O] (5) of Robson type macrocyclic Schiff-base ligands derived from [2 + 2] condensation of 4-methyl-2,6-diformylphenol with 1,3-diaminopropane (H2L1), 1,2-diaminoethane (H2L2), 1,2-diaminopropane (H2L3), 1,2-diamino-2-methylpropane (H2L4) and 1,2- diaminocyclohexane (H2L5), respectively have been synthesized and characterized. Catecholase activity of those complexes using 3,5-di-tert-butylcatechol as substrate has been investigated in two solvents, methanol and acetonitrile. The role of the solvent and of the steric properties of the macrocyclic ligand of these complexes on their catecholase activity has been examined thoroughly. Acetonitrile is observed to be a better solvent than methanol as far as their catalytic activity is concerned. However, methanol reveals to be a better choice to identify the enzyme–substrate adduct. The investigation also prompted that chelate ring size does affect on the catalytic efficiency: 6-membered ring (as in H2L1) exhibits better activity than its 5-membered counterpart (as in H2L2). The activity of the 5-membered counter parts also depend upon the steric factor. Moreover, the catalytic activity of the complexes is enhanced to a signifi- cant extent by increasing the bulkiness of the substituents on the backbone of macrocyclic H2L2 ligands.

About the journal
JournalData powered by TypesetJournal of Molecular Catalysis A: Chemical
PublisherData powered by TypesetElsevier BV
ISSN1381-1169
Open AccessNo