Kinetics of formation and dissociation of lanthanide(<scp>iii</scp>) complexes with the 13-membered macrocyclic ligand TRITA<sup>4−</sup>
作者:Edina Balogh、Raphaël Tripier、Robert Ruloff、Éva Tóth
DOI:10.1039/b418991d
日期:——
intermediate in size between the widely studied and medically used 12-membered DOTA(4-) and the 14-membered TETA(4-). The kinetic inertness of GdTRITA(-) was characterized by the rates of exchange reactions with Zn(2+) and Eu(3+). In the Zn(2+) exchange, a second order [H(+)] dependence was found for the pseudo-first-order rate constant (k(0)=(4.2 +/- 0.5) x 10(-7) s(-1); k'=(3.5 +/- 0.3) x 10(-1) M(-1)s(-1)
四氮杂大环配体TRITA(4-)的大小介于广泛研究和医学使用的12元DOTA(4-)和14元TETA(4-)之间。GdTRITA(-)的动力学惰性是通过与Zn(2+)和Eu(3+)进行交换反应的速率来表征的。在Zn(2+)交换中,发现伪一阶速率常数(k(0)=(4.2 +/- 0.5)x 10(-7)s的二阶[H(+)]依赖性。 (-1); k'=(3.5 +/- 0.3)x 10(-1)M(-1)s(-1),k“ =(1.4 +/- 0.4)x 10(3)M(- 2)s(-1))。在Eu(3+)交换中,pH <5时,速率随交换离子浓度的增加而降低,这可能是由于双核GdTRITAEu(2+)物种的过渡形成所致。在生理pH值下,GdTRITA(-)的动力学惰性大大低于GdDOTA(-)(t(1/2)= 444 h(25摄氏度)vs.3。8 x 10(5)h(分别为37摄氏度)。但是,GdTR