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Bioinorganic Chemistry and Applications
Volume 2010, Article ID 125717, 8 pages
Research Article

pH-Potentiometric Investigation towards Chelating Tendencies of -Hydroquinone and Phenol Iminodiacetate Copper(II) Complexes

1Department of Chemistry, University of Cyprus, 1678 Nicosia, Cyprus
2Agricultural Production and Biotechnology and Food Science, Cyprus University of Technology, P. O. Box 50329, 3603 Lemesos, Cyprus

Received 27 January 2010; Accepted 23 March 2010

Academic Editor: Spyros P. Perlepes

Copyright © 2010 Marios Stylianou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Copper ions in the active sites of several proteins/enzymes interact with phenols and quinones, and this interaction is associated to the reactivity of the enzymes. In this study the speciation of the with iminodiacetic phenolate/hydroquinonate ligands has been examined by pH-potentiometry. The results reveal that the iminodiacetic phenol ligand forms mononuclear complexes with at acidic and alkaline pHs, and a binuclear -bridged complex at pH range from 7 to 8.5. The binucleating hydroquinone ligand forms only 2 : 1 metal to ligand complexes in solution. The pK values of the protonation of the phenolate oxygen of the two ligands are reduced about 2 units after complexation with the metal ion and are close to the pK values for the copper-interacting tyrosine phenol oxygen in copper enzymes.