Equilibrium, kinetic and structural studies of AAZTA complexes with Ga 3+, In3+ and Cu2+

Zsolt Baranyai, Fulvio Uggeri, Alessandro Maiocchi, Giovanni B. Giovenzana, Camilla Cavallotti, Anett Takács, Imre Tóth, István Bányai, Attila Bényei, Erno Brucher, Silvio Aime

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31 Citations (Scopus)


A detailed study of the structures, thermodynamic stabilities and kinetics of the dissociation of Ga3+, In3+ and Cu2+ complexes formed with the heptadentate ligand AAZTA is reported. The stability constants (log KML) of the AAZTA complexes of Ga3+, In3+ and Cu2+ are 22.18, 29.58 and 22.27, respectively, which suggests that the seven-membered-ring skeleton is suited to the accommodation of these metal ions. The solid-state structure of [Cu(H 2AAZTA)]·H2O shows a distorted octahedral coordination. The equatorial coordination sites of Cu2+ are occupied by one of the ring N atoms, a water O atom, one of the carboxylate O atoms and the N atom of the iminodiacetate moiety. The other ring N atom and the carboxylate O atom of the iminodiacetate moiety coordinate to the Cu 2+ in the axial positions. In the pH range 4.5-8.5, Ga3+ is present in the form of the highly stable [Ga(AAZTA)OH]2- (log βGaLH-1 = 17.69) The exchange reactions of [Ga(AAZTA)OH] 2- with Cu2+ and transferrin are very slow and mainly occur through the spontaneous dissociation of the complex close to physiological conditions. The half-life for the dissociation of [Ga(AAZTA)OH]2- is t1/2 = 23 h at pH = 7.5 and 25 °C in 0.025 M NaHCO3 and 0.15 M NaCl. The high conditional stability, fast formation and sufficiently slow dissociation of [Ga(AAZTA)OH]2- represent promising properties for the complexation and diagnostic applications of radioactive Ga isotopes.

Original languageEnglish
Pages (from-to)147-162
Number of pages16
JournalEuropean Journal of Inorganic Chemistry
Issue number1
Publication statusPublished - Jan 1 2013


  • Complexation
  • Copper
  • Gallium
  • Imaging agents
  • Indium
  • Kinetics
  • Radiopharmaceuticals
  • Thermodynamics

ASJC Scopus subject areas

  • Inorganic Chemistry

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