Intramolecular Hydrogen Bonding Restricts Gd–Aqua‐Ligand Dynamics

Aqua ligands can undergo rapid internal rotation about the M−O bond. For magnetic resonance contrast agents, this rotation results in diminished relaxivity. Herein, we show that an intramolecular hydrogen bond to the aqua ligand can reduce this internal rotation and increase relaxivity. Molecular mo...

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Bibliographic Details
Published in:Angewandte Chemie 2017-05, Vol.129 (20), p.5695-5698
Main Authors: Boros, Eszter, Srinivas, Raja, Kim, Hee‐Kyung, Raitsimring, Arnold M., Astashkin, Andrei V., Poluektov, Oleg G., Niklas, Jens, Horning, Andrew D., Tidor, Bruce, Caravan, Peter
Format: Article
Language:English
Subjects:
Aqua-Ionen-Dynamik
Chemical bonds
Chemistry
Contrast agents
Coordination compounds
Gadolinium
Gadolinium-Komplexe
Hydrogen bonding
Hydrogen bonds
Internal water
Ligands
Magnetic resonance
Molecular dynamics
Molecular modelling
Moleküldynamik
Relaxivität
Rotation
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Summary:Aqua ligands can undergo rapid internal rotation about the M−O bond. For magnetic resonance contrast agents, this rotation results in diminished relaxivity. Herein, we show that an intramolecular hydrogen bond to the aqua ligand can reduce this internal rotation and increase relaxivity. Molecular modeling was used to design a series of four Gd complexes capable of forming an intramolecular H‐bond to the coordinated water ligand, and these complexes had anomalously high relaxivities compared to similar complexes lacking a H‐bond acceptor. Molecular dynamics simulations supported the formation of a stable intramolecular H‐bond, while alternative hypotheses that could explain the higher relaxivity were systematically ruled out. Intramolecular H‐bonding represents a useful strategy to limit internal water rotational motion and increase relaxivity of Gd complexes. Angehalten: Bei Gd3+‐Komplexen für die Kernspintomographie führt die schnelle Rotation des Aqua‐Liganden um die Gd‐O‐Bindung zu einer Verringerung der Relaxivität. Diese innere Bewegung kann durch eine intramolekulare Wasserstoffbrücke zum Aqua‐Liganden angehalten werden.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.201702274