GdIII Complexes with Fast Water Exchange and High Thermodynamic Stability: Potential Building Blocks for High-Relaxivity MRI Contrast Agents
作者:Sabrina Laus、Robert Ruloff、Éva Tóth、André E. Merbach
DOI:10.1002/chem.200204612
日期:2003.8.4
remarkably fast water exchange. When one acetate of DTPA(5-) is substituted by a propionate, the water exchange rate on the Gd(III) complex increases by a factor of 10 (k(ex)298=31x10(6) s(-1)). The [Gd(dptpa)](2-) chelate has no inner-sphere water molecule. The protonation constants of the EPTPA-bz-NO(2) (5-) and DPTPA(5-) ligands and the stability constants of their complexes with Gd(III), Zn(II), Cu(II)
基于九配位一水合Gd(III)聚(氨基羧酸盐)配合物内球的结构考虑,我们通过在水结合位点周围引起空间压缩来成功促进水交换。我们通过替换一个(EPTPA(5-))或两个(DPTPA(5-) )通过丙烯桥连接主链上的乙烯桥,或通过丙酸酯臂(DTTA-prop(5-)配位一个乙酸酯。配体EPTPA(5-)还带有硝基苄基连接基团(EPTPA-bz-NO( 2)(5-)),以使螯合物与大分子偶联。水交换速率由可变温度(17)O NMR和EPR研究组合得出,比[Gd(eptpa-bz-NO(2))(H(2)O)](2-)和[Gd(eptpa)(H(2)O)](2-)高两个数量级在[Gd(dtpa)(H(2)O)](2-)上(分别为k(ex)298 = 150x10(6),330x10(6)和3.3x10(6)s(-1))。这对于获得基于Gd(III)的大环MRI造影剂的最大质子弛豫性是最佳的。通过可变压力(17)O