The Solution Structure and Dynamics of MRI Probes Based on Lanthanide(III) DOTA as Investigated by DFT and NMR Spectroscopy
The Solution Structure and Dynamics of MRI Probes Based on Lanthanide(III) DOTA as Investigated by DFT and NMR Spectroscopy
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DFT 和 NMR 波谱研究基于镧系 (III) DOTA 的 MRI 探针的溶液结构和动力学
DOI：
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
C. Platas‐Iglesias
中科院分区：
文献类型：
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作者：
C. Platas‐Iglesias
顺磁性镧系（III）配合物在水溶液中的稳定性由于其在磁共振成像（MRI）中作为造影剂的重要性而在近年来得到越来越多的关注。镧系元素（III）与衍生自1，4，7，10-四氮杂环十二烷（cyclen）的大环配体的配合物由于其高的热力学稳定性和动力学惰性而被广泛用于MRI探针的设计。更有效的造影剂的合理设计需要更好地理解这些系统在溶液中的结构和动力学。这篇文章回顾了作者和他的合作者对镧系元素（III）配合物与不同的基于环戊二烯的配体和密切相关的系统的溶液结构和动力学的工作。DFT计算提供了这些配合物的不同立体异构体的分子几何形状和相对能量，与实验数据吻合良好。借助密度泛函理论（DFT）计算进行的构象分析通过研究YbIII诱导的1H NMR顺磁位移进行了验证，该位移编码了所观察到的NMR核相对于LnIII离子的位置信息。此外，DFT计算提供了一个更好的理解的动态过程负责的平方反棱柱（SAP）和扭曲的平方反棱柱（TSAP）异构体之间的相互转换，这些配合物在溶液中，这可能会通过反转的cyclen单元或旋转的悬垂臂。从理论计算得到的活化势垒显示出良好的协议与实验值从变温NMR光谱。本文提出的工作表明，DFT计算结合NMR光谱提供了详细的信息，镧系元素（III）配合物的结构和动力学在分子水平上，并代表一个强大的工具表征镧系元素（III）配合物相关的MRI造影剂领域。
Paramagnetic lanthanide(III) complexes stable in aqueous solutions have gained increasing interest in the recent years due to their importance as contrast agents in magnetic resonance imaging (MRI). Lanthanide(III) complexes with macrocyclic ligands derived from 1,4,7,10-tetraazacyclododecane (cyclen) are widely used for the design of MRI probes because of their high thermodynamic stability and kinetic inertness. The rational design of more efficient contrast agents requires a better understanding of the structure and dynamics of these systems in solution. This contribution reviews the work of the author and his collaborators on the solution structure and dynamics of lanthanide(III) complexes with different cyclen-based ligands and closely related systems. DFT calculations provide molecular geometries and relative energies of the different stereoisomers of these complexes in good agreement with the experimental data. The conformational analysis performed with the aid of density functional theory (DFT) calculations was validated with the investigation of the YbIII-induced 1H NMR paramagnetic shifts, which encode information on the position of the observed NMR nuclei with respect to the LnIII ion. Additionally, DFT calculations provide a better understanding of the dynamic processes responsible for the interconversion between the square-antiprismatic (SAP) and twisted-square-antiprismatic (TSAP) isomers of these complexes in solution, which might proceed through the inversion of the cyclen unit or the rotation of the pendant arms. The activation barriers obtained from theoretical calculations show a good agreement with the experimental values obtained from variable-temperature NMR spectroscopy. The work presented in this paper shows that DFT calculations in combination with NMR spectroscopy provide detailed information on the structure and dynamics of lanthanide(III) complexes at the molecular level and represent a powerful tool for the characterization of lanthanide(III) complexes relevant to the field of MRI contrast agents.
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