NMR Research Unit, Faculty of Science, University of Oulu, P.O.Box 3000, 90014 Oulu, Finland.
Phys Chem Chem Phys. 2022 Sep 21;24(36):22109-22114. doi: 10.1039/d2cp02944h.
Molecular exchange between different physical or chemical environments occurs due to either diffusion or chemical transformation. Nuclear magnetic resonance (NMR) spectroscopy provides a means of understanding the molecular exchange in a noninvasive way and without tracers. Here, we introduce a novel two dimensional, single-scan ultrafast Laplace NMR (UF LNMR) method to monitor molecular exchange using transverse relaxation as a contrast. The UF - relaxation exchange spectroscopy (REXSY) method shortens the experiment time by one to two orders of magnitude compared to its conventional counterpart. Contrary to the conventional EXSY, the exchanging sites are distinguished based on relaxation times instead of chemical shifts, making the method especially useful for systems including physical exchange of molecules. Therefore, the UF REXSY method offers an efficient means for quantification of exchange processes in various fields such as cellular metabolism and ion transport in electrolytes. As a proof of principle, we studied a halogen-free orthoborate based ionic liquid system and followed molecular exchange between molecular aggregates and free molecules. The results are in good agreement with the conventional exchange studies. Due to the single-scan nature, the method potentially significantly facilitates the use of modern hyperpolarization techniques to boost the sensitivity by several orders of magnitude.
由于扩散或化学转化，不同物理或化学环境之间会发生分子交换。核磁共振（NMR）光谱提供了一种非侵入性且无需示踪剂的方法来理解分子交换。在这里，我们引入了一种新颖的二维、单扫描超快拉普拉斯 NMR（UF LNMR）方法，通过横向弛豫作为对比来监测分子交换。与传统方法相比，UF-弛豫交换光谱（REXSY）方法将实验时间缩短了一到两个数量级。与传统的 EXSY 不同，交换位点是根据弛豫时间而不是化学位移来区分的，这使得该方法特别适用于包括分子物理交换在内的系统。因此，UF REXSY 方法为在各种领域（如细胞代谢和电解质中的离子传输）中定量交换过程提供了一种有效的手段。作为原理验证，我们研究了一种无卤素的正硼酸酯基离子液体体系，并跟踪了分子聚集体和游离分子之间的分子交换。结果与传统的交换研究非常吻合。由于单次扫描的性质，该方法有可能显著促进现代极化技术的使用，将灵敏度提高几个数量级。
