Torres Felix, Renn Alois, Riek Roland
Laboratory of Physical Chemistry, ETH Zürich, Zurich, 8093, Switzerland.
Magn Reson (Gott). 2021 May 12;2(1):321-329. doi: 10.5194/mr-2-321-2021. eCollection 2021.
Sensitivity being one of the main hurdles of nuclear magnetic resonance (NMR) can be gained by polarization techniques including chemically induced dynamic nuclear polarization (CIDNP). Kaptein demonstrated that the basic mechanism of the CIDNP arises from spin sorting based on coherent electron-electron nuclear spin dynamics during the formation and the recombination of a radical pair in a magnetic field. In photo-CIDNP of interest here the radical pair is between a dye and the molecule to be polarized. Here, we explore continuous-wave (CW) photo-CIDNP (denoted CW-photo-CIDNP) with a set of 10 tryptophan and tyrosine analogues, many of them newly identified to be photo-CIDNP active, and we observe not only signal enhancement of 2 orders of magnitude for H at 600 MHz (corresponding to 10 000 times in measurement time) but also reveal that polarization enhancement correlates with the hydrophobicity of the molecules. Furthermore, the small chemical library established indicates the existence of many photo-CIDNP-active molecules.
灵敏度是核磁共振（NMR）的主要障碍之一，可通过包括化学诱导动态核极化（CIDNP）在内的极化技术来提高。卡普泰因证明，CIDNP的基本机制源于在磁场中自由基对形成和重组过程中基于相干电子-电子核自旋动力学的自旋分选。在本文所关注的光致CIDNP中，自由基对存在于染料和待极化分子之间。在此，我们用一组10种色氨酸和酪氨酸类似物探索连续波（CW）光致CIDNP（记为CW-光致CIDNP），其中许多是新发现的具有光致CIDNP活性的物质，我们不仅观察到在600 MHz下氢信号增强了2个数量级（相当于测量时间增加了10000倍），还揭示了极化增强与分子的疏水性相关。此外，所建立的小型化学文库表明存在许多具有光致CIDNP活性的分子。
