Equilibrium, Kinetic and Structural Studies of AAZTA Complexes with Ga3+, In3+ and Cu2+1. Issue 1 (21st November 2012)

• Record Type: Journal Article
• Authors: Baranyai, Zsolt; Uggeri, Fulvio; Maiocchi, Alessandro; Giovenzana, Giovanni B.; Cavallotti, Camilla; Takács, Anett; Tóth, Imre; Bányai, István; Bényei, Attila; Brucher, Ernő; Aime, Silvio
• Is Part Of: European journal of inorganic chemistry. Issue 1(2013)
• Page Start: 147
• Page End: 162
• Publication Date: 2012-11-21
• Subjects: Gallium -- Indium -- Copper -- Complexation -- Thermodynamics -- Kinetics­ -- Radiopharmaceuticals -- Imaging agents; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201201108
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: A detailed study of the structures, thermodynamic stabilities and kinetics of the dissociation of Ga 3+, In 3+ and Cu 2+ complexes formed with the heptadentate ligand AAZTA is reported. The stability constants (log K ML ) of the AAZTA complexes of Ga 3+, In 3+ and Cu 2+ 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(H2 AAZTA)]· H2 O shows a distorted octahedral coordination. The equatorial coordination sites of Cu 2+ 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, Ga 3+ is present in the form of the highly stable [Ga(AAZTA)OH] 2– (log β GaLH–1 = 17.69) The exchange reactions of [Ga(AAZTA)OH] 2– with Cu 2+ 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 t 1/2 = 23 h at pH = 7.5 and 25 °C in 0.025M NaHCO3 and 0.15M 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. Abstract : A full account of the solution structures, thermodynamics and kinetic stabilities of the complexes of AAZTA formed with metal ions of interest for radiodiagnostic applications (Ga 3+, In 3+ and Cu 2+ ) is presented. Excellent stability data, including high kinetic inertness, support the use of AAZTA in the development of novel and safe metal‐based radiopharmaceuticals.