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Copper(II), nickel(II) and zinc(II) complexes of amino acids containing bis(imidazol-2-yl)methyl residues

Osz, Katalin and Várnagy, Katalin and Süli-Vargha, Helga and Sanna, Daniele and Micera, Giovanni and Sóvágó, Imre (2002) Copper(II), nickel(II) and zinc(II) complexes of amino acids containing bis(imidazol-2-yl)methyl residues. Inorganica Chimica Acta, Vol. 339 (15), p. 373-382. ISSN 0020-1693. Article.

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DOI: 10.1016/S0020-1693(02)00954-4

Abstract

Copper(II), nickel(II) and zinc(II) complexes of Phe-BIMA and His-BIMA were studied by potentiometric, UV–Vis and EPR spectroscopic methods. The nitrogen donor atoms of the bis(imidazol-2-yl)methyl residues were described as the primary metal binding sites in all systems studied. Deprotonation and coordination of the terminal amino and amide nitrogen atoms took place in the copper(II) complexes of both ligands and resulted in the formation of dinuclear complexes ([Cu2H−2L2]2+) containing [NH2, N, N(Im)] tridentate ligands and imidazole bridging. The presence of the histidyl side chain provides a great versatility in the complex formation reactions of His-BIMA. The existence of the species [Cu2L2]4+ was detected in slightly acidic solution and its structure was described as a mixture of three isomeric forms. Deprotonation of the imidazole-N(1)H donor functions was detected under slightly alkaline conditions with pK values of 8.13 and 8.93. An excess of copper(II) ions shifted this reactions even into the slightly acidic pH range and resulted in the formation of a trinuclear complex ([Cu3H-4L2]2+).

Item Type:Article
ID Code:1408
Status:Published
Refereed:Yes
Uncontrolled Keywords:Transition metal ion, histidine, bis(imidazolyl), EPR, potentiometry, stability constants
Subjects:Area 03 - Scienze chimiche > CHIM/03 Chimica generale e inorganica
Divisions:001 Università di Sassari > 01 Dipartimenti > Chimica
002 Altri enti e centri di ricerca del Nord Sardegna > CNR-Consiglio Nazionale delle Ricerche > Istituto di chimica biomolecolare, Sassari
Publisher:Elsevier
ISSN:0020-1693
Additional Information:Pubblicato online il 2 maggio 2002.
Deposited On:18 Aug 2009 10:05

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