NMR EVIDENCE OF A LONG EXCHANGE LIFETIME FOR THE COORDINATED WATER IN LN(III)-BIS(METHYL AMIDE)-DTPA COMPLEXES (LN=GD, DY)
NMR EVIDENCE OF A LONG EXCHANGE LIFETIME FOR THE COORDINATED WATER IN LN(III)-BIS(METHYL AMIDE)-DTPA COMPLEXES (LN=GD, DY)
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DOI：
10.1021/ic00099a021
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发表时间：
1994-10-12
影响因子：
4.6
通讯作者：
VIRTUANI, M
中科院分区：
文献类型：
--
作者：
AIME, S;BOTTA, M;VIRTUANI, M
测量并分析了不同温度下顺磁配合物Gd-BMA-DTPA的水质子纵向弛豫速率与磁场的关系。有趣的是，我们已经发现溶剂弛豫率在很大程度上受金属螯合物上的配位位点中的水分子的停留寿命（τ（M））的影响。在298 K时tau（M）的计算值为0.81 μ s，即比最近报道的Gd-DTPA值长4倍，比聚（氨基羧酸盐）络合物的NMR谱分析中通常假定的值长得多。这一结果也得到了证实的替代方法的结构类似的Dy（III）复合物。在后一种情况下，从顺磁贡献的H-1 NMR化学位移和横向弛豫率的溶剂水质子的测量，我们评估的驻留寿命τ（M）迭代求解Swift-Connick方程。
The magnetic field dependence of the water proton longitudinal relaxation rate for the paramagnetic complex Gd-BMA-DTPA has been measured and analyzed at different temperatures. Interestingly we have found that the solvent relaxivity is largely affected by the residence lifetime (tau(M)) of the water molecule in the coordination site on the metal chelate. The calculated values for tau(M) at 298 K is 0.81 mu s, i.e. 4-fold longer than the values recently reported for Gd-DTPA and much longer than the values commonly assumed in the analysis of NMRD profiles of poly(amino carboxylate) complexes. This result has been also confirmed by an alternative approach for the structurally analogous Dy(III) complex. In this latter case, from the measurement of the paramagnetic contribution to H-1 NMR chemical shift and transverse relaxation rate of the solvent water protons, we evaluated the residence lifetime tau(M) by solving iteratively the Swift-Connick equations.