STRUCTURE AND DYNAMICS OF LANTHANOID TETRAAZACYCLODODECANETETRAACETATE DOTA COMPLEXES IN SOLUTION
STRUCTURE AND DYNAMICS OF LANTHANOID TETRAAZACYCLODODECANETETRAACETATE DOTA COMPLEXES IN SOLUTION
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DOI：
10.1002/cber.19931260404
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发表时间：
1993-04-01
期刊：
影响因子：
--
通讯作者：
ROTH, K
中科院分区：
文献类型：
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作者：
HOEFT, S;ROTH, K
在水溶液中，镧系元素 DOTA 配合物以两种立体异构体的混合物形式存在，其结构已根据观察到的 EuDOTA 和 YbDOTA 的 H-1-NMR 化学位移的偶极部分确定。 DELTA(deltadeltadeltadelta)异构体的相对浓度随着离子半径的减小而减小。对于EuDOTA，观察到1:4的混合物，并且主要异构体具有DELTA(lambdalambdalambda)结构，该结构也存在于固态中。通过 H-1-NMR 交换光谱 (EXSY) 检测到两个独立的分子内异构化。更快的过程是四个乙酸酯取代基围绕 C-N 键的旋转 [DELTA(lambdalambdalambdalambda) --> LAMBDA(lambdalambdalambdalambda) 异构化]。环癸烷环反转较慢[DELTA(lambdalambdalambdalambda) --> DELTA(deltadeltadeltadelta)异构化]。 DELTA(lambdalambdalambdalambda) 主要异构体分子内外消旋化为其 LAMBDA(deltadeltadeltadelta) 对映体，包括 DELTA(lambdalambdalambdalambda) --> LAMBDA(lambdalambdalambdalambda) --> 中的两个连续异构化 LAMBDA（deltadeltadeltadelta）序列，是最慢的过程。
In aqueous solution lanthanoid DOTA complexes exist as a mixture of two stereoisomers, and their structures have been determined from the dipolar parts of the observed H-1-NMR chemical shifts for EuDOTA and YbDOTA. The relative concentration of the DELTA(deltadeltadeltadelta) isomer decreases with decreasing ionic radius. For EuDOTA a 1: 4 mixture is observed, and the main isomer has a DELTA(lambdalambdalambdalambda) structure which is also found in the solid state. Two independent intramolecular isomerizations were detected by H-1-NMR Exchange Spectroscopy (EXSY). The faster process is the rotation of the four acetate substituents around the C-N bonds [DELTA(lambdalambdalambdalambda) --> LAMBDA(lambdalambdalambdalambda) isomerization]. The cyclodecane ring inversion is slower [DELTA(lambdalambdalambdalambda) --> DELTA(deltadeltadeltadelta) isomerization]. The intramolecular racemization of the DELTA(lambdalambdalambdalambda) main isomer into its LAMBDA(deltadeltadeltadelta) enantiomer includes two successive isomerizations in a DELTA(lambdalambdalambdalambda) --> LAMBDA(lambdalambdalambdalambda) --> LAMBDA(deltadeltadeltadelta) sequence and is the slowest process.