Equilibrium, Kinetic and Structural Studies of AAZTA Complexes with Ga3+, In3+ and Cu2+
Equilibrium, Kinetic and Structural Studies of AAZTA Complexes with Ga3+, In3+ and Cu2+
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DOI：
10.1002/ejic.201201108
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发表时间：
2013-01-01
影响因子：
2.3
通讯作者：
Aime, Silvio
中科院分区：
文献类型：
--
作者：
Baranyai, Zsolt;Uggeri, Fulvio;Aime, Silvio
报道了与七齿配体 AAZTA 形成的 Ga3+、In3+ 和 Cu2+ 配合物的结构、热力学稳定性和解离动力学的详细研究。 Ga3+、In3+和Cu2+的AAZTA配合物的稳定常数(logKML)分别为22.18、29.58和22.27，这表明七元环骨架适合容纳这些金属离子。 [Cu(H(2)AAZTA)]中心点H2O的固态结构显示出扭曲的八面体配位。 Cu2+ 的赤道配位位点被环 N 原子之一、水 O 原子、羧酸根 O 原子之一和亚氨基二乙酸酯部分的 N 原子占据。另一个环N原子和亚氨基二乙酸酯部分的羧酸O原子在轴向位置与Cu2+配位。在pH 4.5-8.5范围内，Ga3+以高度稳定的[Ga(AAZTA)-OH](2-) (log beta(GaLH-1) = 17.69)形式存在。[Ga(AAZTA) OH](2-)与Cu2+和转铁蛋白的交换反应非常缓慢，主要通过接近生理条件的复合物自发解离发生。在 pH = 7.5 和 25 摄氏度、0.025 M NaHCO3 和 0.15 M NaCl 中，[Ga(AAZTA) OH](2-) 解离的半衰期为 t(1/2) = 23 小时。 [Ga(AAZTA) OH](2-) 的高条件稳定性、快速形成和足够慢的解离代表了放射性 Ga 同位素络合和诊断应用的有前景的特性。
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 (logKML) 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(2)AAZTA)]center dot 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 Cu2+ 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 beta(GaLH-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 t(1/2) = 23 h at pH = 7.5 and 25 degrees 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.