Sensitivity-Enhanced High-Field Solution-State NMR by Gyrotron-Driven DNP

核磁共振（NMR）是表征分子结构和动力学的最重要和最广泛使用的方法之一，但它的灵敏度-特别是在应用于液体样品时-对于许多重要的应用是不够的。 在化学部化学测量成像项目的支持下，佛罗里达州立大学国家高磁场实验室（NHMFL）的Sungsool Wi、Lucio Frydman和Stephen Hill博士正在努力实现最近技术和概念突破的溶液状态适用性，这些突破极大地提高了高场NMR表征固体的灵敏度。 扩展到液体（包括水溶液）可能会在化学和生物化学中产生变革性的后果，特别是对于表征有限数量的小到中等大小的分子。潜在的应用包括天然产物和药物化学;石油和聚合物分析化学;食品和环境科学;和代谢组学。NHMFL的设置促进了技术的广泛传播，并为不同应用领域的外部用户提供了可访问性。 Wi小组正在开发用于高磁场下大体积样品（100 uL）的溶液状态Overhauser增强动态核极化（ODNP）NMR（= 14.1 T/600 MHz），其目的在于使用常规的和低温冷却的溶液态NMR探头在典型条件下显著提高NMR灵敏度。该研究利用了最近开发的在395 GHz下工作的高功率Gyrotron源，具有匹配的准光学技术，以及包含定制NMR探针的600 MHz NMR溶液状态光谱仪。这些突破正在扩展到更广泛的有机分析物，采用新的硬件，使ODNP增强双共振实验在低粘度，低介电损耗溶剂，如己烷，在超临界流体，并使用新的自由基组合。原位EPR光谱，在同一个600 MHz的光谱仪上执行，并通过修改现有的准光学接口，被用来提供独特的机制见解，并进一步优化这些ODNP增强NMR experiments.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Nuclear magnetic resonance (NMR) is one of the most important and widely used methods for characterizing molecular structure and dynamics, but its sensitivity - especially when applied to liquid samples - is inadequate for many important applications. With support from the Chemical Measurement & Imaging program in the Division of Chemistry, Drs. Sungsool Wi, Lucio Frydman, and Stephen Hill at Florida State University's National High Magnetic Field Laboratory (NHMFL) are working to achieve solution-state applicability for recent technological and conceptual breakthroughs that have dramatically improved the sensitivity of high-field NMR for characterization of solids. Extension to liquids (including aqueous solutions) may have transformative consequences in chemistry and biochemistry, particularly for characterizing limited quantities of small to medium-sized molecules. Potential applications include natural products and pharmaceutical chemistry; petroleum and polymer analytical chemistry; food and environmental sciences; and metabolomics. The NHMFL setting facilitates wide dissemination of the techniques, and provides accessibility to outside users in diverse application areas. It also enables extensive outreach efforts targeting high school students and involvement of undergraduates.The Wi group is developing solution-state Overhauser-enhanced dynamic nuclear polarization (ODNP) NMR for large volume samples ( 100 uL) at high magnetic fields (= 14.1 T/600 MHz), aiming to dramatically improve NMR sensitivity under typical conditions using conventional and cryogenically-cooled solution-state NMR probe heads. The research leverages the recent development of a high-power Gyrotron source operating at 395 GHz, with matching quasi-optical technologies, and a 600 MHz NMR solution-state spectrometer incorporating a customized NMR probe. These breakthroughs are being extended to a far wider range of organic analytes by employing new hardware which enables ODNP-enhanced double-resonance experiments in low-viscosity, low-dielectric-loss solvents such as hexane, in supercritical fluids, and using novel radical combinations. In situ EPR spectroscopy, executed in the same 600 MHz spectrometer and enabled through modifications to the existing quasioptical interface, is being employed to provide unique mechanistic insights and to further optimize these ODNP-enhanced NMR experiments.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.