Jocher Christoph J, Botta Mauro, Avedano Stefano, Moore Evan G, Xu Jide, Aime Silvio, Raymond Kenneth N
Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.
Inorg Chem. 2007 Jun 11;46(12):4796-8. doi: 10.1021/ic700399p. Epub 2007 May 11.
Relaxometry and solution thermodynamic measurements show that Gd(H(2,2)-1,2-HOPO) is a good candidate as a contrast agent for magnetic resonance imaging (MRI-CA). Acidic, octadentate H(2,2)-1,2-HOPO forms a very stable Gd(III) complex [pGd=21.2(2)]. The coordination sphere at the Gd(III) center is completed by one water molecule that is not replaced by common physiological anions. In addition, this ligand is highly selective for Gd(III) binding in the presence of Zn(II) or Ca(II). The symmetric charge distribution of the 1,2-HOPO chelates is associated with favorably long electronic relaxation time T1,2e comparable to those of GdDOTA. This, in addition to the fast water exchange rate typical of HOPO chelates, improves the relaxivity to r1p=8.2 mM-1 s-1 (0.47 T). This remarkably high value is unprecedented for small-molecule, q=1 MRI-CA.
弛豫测量和溶液热力学测量表明，钆（H(2,2)-1,2-HOPO）是一种很好的磁共振成像造影剂（MRI-CA）候选物。酸性八齿配体H(2,2)-1,2-HOPO形成了一种非常稳定的钆（III）配合物[pGd = 21.2(2)]。钆（III）中心的配位球由一个水分子完成，该水分子不会被常见的生理阴离子取代。此外，在锌（II）或钙（II）存在的情况下，这种配体对钆（III）的结合具有高度选择性。1,2-HOPO螯合物的对称电荷分布与良好的长电子弛豫时间T1,2e相关，与钆喷酸葡胺的弛豫时间相当。此外，HOPO螯合物典型的快速水交换速率提高了弛豫率，达到r1p = 8.2 mM-1 s-1（0.47 T）。对于小分子、q = 1的MRI-CA来说，这个极高的值是前所未有的。
