Catechol oxidase activity of dicopper complexes with N-donor ligands

Katalin Selmeczi, Marius Réglier, Michel Giorgi, Gábor Speier

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Abstract

The catecholase activity of two dicopper(II) complexes [Cu 2(L1)(CF3SO3)2(H 2O)4](CF3SO3)2 (1) and [Cu2(L2O)](CF3SO3)](CF 3SO3)2 (2) containing the ligands 1,3-bis{N,N-bis(2-[2-pyridyl]ethyl)}aminopropane (L1) and 1,3-bis{N,N-bis(2-[2-pyridyl]ethyl)}amino-2-hydroxypropane (L2OH) was studied as functional as well as structural models for the type 3 copper enzyme, catechol oxidase. The X-ray structure of 1 in solid form shows a Cu-Cu distance of 7.840 Å, while in 2 the Cu-Cu distance is only 3.699 Å. Complex 1 can have flexible conformations in solution while the other is being fixed by the bridging alkoxo group. The catalytic activity of the complexes 1 and 2 on the oxidation of 3,5-di-tert-butylcatechol was determined spectrophotometrically by monitoring the increase of the 3,5-di-tert-butyl-o-benzoquinone characteristic absorption at 400 nm over time in methanol saturated with O2 at 25 °C. The complexes were able to oxidize 3,5-di-tert-butylcatechol to the corresponding o-quinone and hydrogen peroxide. A kinetic treatment of the data based on steady-state treatment and Michaelis-Menten approach was applied. Mechanisms for the catalytic reactions are proposed, which show that with complex 1 copper(I) dioxygen chemistry determines the kinetic scenario, while with complex 2 the reaction follows a Michaelis-Menten type kinetics.

Original languageEnglish
Pages (from-to)191-201
Number of pages11
JournalCoordination Chemistry Reviews
Volume245
Issue number1-2
DOIs
Publication statusPublished - Oct 2003

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Keywords

  • Catechol oxidase models
  • Dinuclear copper complexes
  • Dioxygen
  • Kinetics

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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