Iridium N-heterocyclic carbene complexes as efficient catalysts for magnetization transfer from para-hydrogen.
Iridium N-heterocyclic carbene complexes as efficient catalysts for magnetization transfer from para-hydrogen.
复制标题
DOI：
10.1021/ja200299u
复制
发表时间：
2011-04-27
影响因子：
15
通讯作者：
Mewis, Ryan E.
中科院分区：
文献类型：
--
作者：
Cowley, Michael J.;Adams, Ralph W.;Atkinson, Kevin D.;Cockett, Martin C. R.;Duckett, Simon B.;Green, Gary G. R.;Lohman, Joost A. B.;Kerssebaum, Rainer;Kilgour, David;Mewis, Ryan E.
虽然通过NMR表征材料在物理和生物科学中非常重要，但它在医学成像中也起着至关重要的作用。由于该方法固有的低灵敏度，这一成功更令人印象深刻。我们在这里建立，[Ir（H）2（IMes）（py）3]Cl经历吡啶（py）的损失以及还原消除H2。这些可逆过程使para-H2和py在磁耦合环境中接触，在3 T下相对于非超极化py，1H NMR信号强度增加了8100倍。已经建立了一种有助于信号平均的装置，以证明该过程的效率由磁化转移步骤期间复合物所经历的磁场强度控制。热力学和动力学数据结合DFT计算揭示了[Ir（H）2（η2-H2）（IMes）（py）2]+的参与，这是反应中不太可能但关键的中间体。氘标记产生额外的60%的信号改善，观察提供了深入了解优化这种方法的策略。
While the characterization of materials by NMR is hugely important in the physical and biological sciences, it also plays a vital role in medical imaging. This success is all the more impressive because of the inherently low sensitivity of the method. We establish here that [Ir(H)2(IMes)(py)3]Cl undergoes both pyridine (py) loss as well as the reductive elimination of H2. These reversible processes bring para-H2 and py into contact in a magnetically coupled environment, delivering an 8100-fold increase in 1H NMR signal strength relative to non-hyperpolarized py at 3 T. An apparatus that facilitates signal averaging has been built to demonstrate that the efficiency of this process is controlled by the strength of the magnetic field experienced by the complex during the magnetization transfer step. Thermodynamic and kinetic data combined with DFT calculations reveal the involvement of [Ir(H)2(η2-H2)(IMes)(py)2]+, an unlikely yet key intermediate in the reaction. Deuterium labeling yields an additional 60% improvement in signal, an observation that offers insight into strategies for optimizing this approach.
登录
查看更多内容
影响因子：
15
作者：
CRABTREE, RH;LAVIN, M;BONNEVIOT, L
通讯作者：
BONNEVIOT, L
影响因子：
4.9
作者：
Aguilar, Juan A.;Elliott, Paul I. P.;Duckett, Simon B.
通讯作者：
Duckett, Simon B.
影响因子：
3.5
作者：
Ross, B. D.;Bhattacharya, P.;Sailasuta, N.
通讯作者：
Sailasuta, N.
影响因子：
4.9
作者：
Vázquez-Serrano, LD;Owens, BT;Buriak, JM
通讯作者：
Buriak, JM
影响因子：
7.4
作者：
Gong, Qingxia;Gordji-Nejad, Ali;Appelt, Stephan
通讯作者：
Appelt, Stephan