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.
