Journal of Solution Chemistry

, Volume 45, Issue 5, pp 712–731 | Cite as

Potentiometric, Thermodynamics and Coordination Properties for Binary and Mixed Ligand Complexes of Copper(II) with Imidazole-4-acetic Acid and Tryptophan or Phenylalanine Aromatic Amino Acids

  • Abeer T. AbdelkarimEmail author
  • Ahmed A. El-Sherif


Binary and ternary complex formation equilibria of copper(II) with imidazole-4-acetic acid (IMA) and some aromatic amino acids such as tryptophan and phenylalanine have been studied from 15 to 45 °C by potentiometric titration. The pH-titrations of the reaction mixtures have shown 1:1:1 (Cu:IMA:amino acid) ternary complex formation. The stability of mixed-ligand complexes was quantitatively compared with the stability of the binary complexes as Δlog10 K, Δlog10 β and log10 X parameters. The speciation of different species in solution has been evaluated as a function of pH. The effect of temperature on protonation of the ligands and formation of mixed ligand complexes was investigated. Thermodynamic parameters were calculated and are discussed. The effect of solvent of the protonation of IMA and Cu–IMA complex formation was also investigated and discussed. Additionally, the stoichiometric protonation constants (log10 β) of imidazole-4-acetic acid and its binary Cu(II)–IMA complexes were determined potentiometrically over a wide range of solvent composition.


Potentiometry Copper(II) Imidazole-4-acetic acid Tryptophan Thermodynamics Species 



Imidazole-4-acetic acid


Phenylalanine amino acid


Tryptophan amino acid


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Authors and Affiliations

  1. 1.Department of Chemistry, Faculty of ScienceCairo UniversityCairoEgypt

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