T1e in four Gd3+ chelates:: LODEPR measurements and models for electron spin relaxation
T1e in four Gd3+ chelates:: LODEPR measurements and models for electron spin relaxation
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DOI：
10.1021/jp0203752
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发表时间：
2002-07-04
影响因子：
2.9
通讯作者：
Clarkson, RB
中科院分区：
文献类型：
--
作者：
Borel, A;Helm, L;Clarkson, RB
在以前的论文中，我们报道了第一个纵向检测的电子顺磁共振（LODEPR）测量两种Gd 3+螯合物水溶液中的快T-1 e值，我们包括了这些弛豫时间的预测值，基于零场分裂（ZEM）参数，来自两个系统的多频EPR数据[Atsarkin，V.A.;德米多夫;瓦斯涅瓦湾一、Odintsov，B. M.;贝尔福德河L.的; Raduchel，B.;克拉克森河B。2001，105，9323-9327]。该分析中使用的模型源自哈德逊和刘易斯的原始工作，没有明确考虑机翼的静态和动态部分。一个更全面的模型松弛在这些S =（7）/（2）系统最近已公布。在这里，我们根据这个新的模型重新检查多频数据，重新计算了T1 e参数，并计算出与实验值更接近的T-1 e新预测。此外，还报告了两种标准螯合物[Gd（DOTA）（H2O）]（-）和[Gd（DTPA）（H2O）]（2-）的LODEPR T-1 e值以及预测的弛豫时间。新模型的重要性和LODEPR值的有效性都得到了这些数据的加强。
In a previous paper, we reported the first longitudinally detected electron paramagnetic resonance (LODEPR) measurements of fast T-1e values in aqueous solutions of two Gd3+ chelates, and we included predicted values for these relaxation times, based on zero field splitting (ZFS) parameters derived from multifrequency EPR data on the two systems [Atsarkin, V. A.; Demidov, V. V.; Vasneva, G. A.; Odintsov, B. M.; Belford, R. L.; Raduchel, B.; Clarkson, R. B. J. Phys. Chem. 2001, 105, 9323-9327]. The model used in that analysis was derived from the original work of Hudson and Lewis and did not explicitly consider the static and dynamic parts of the ZFS. A more comprehensive model for relaxation in these S = (7)/(2) systems has been recently published. Here, we reexamine the multifrequency data in light of this new model, recalculate the ZFS parameters, and calculate new predictions for T-1e which much more closely agree with experimental values. Additionally, the LODEPR T-1e values for two standard chelates, [Gd(DOTA)(H2O)](-) and [Gd(DTPA)(H2O)](2-) are reported, together with predicted relaxation times. Both the importance of the new model and the validity of the LODEPR values are strengthened by these data.