Collaborative Research: Continuous-Flow Hyperpolarization of Liquids Utilizing Parahydrogen and Heterogeneous Catalysis

在化学系（CHE）化学测量和成像（CMI）项目的支持下，另外两个化学系项目——化学结构、动力学和机制-A （CSDM-A）和化学催化（CAT）以及分子和细胞生物科学（MCB）部门的分子生物物理集群的部分共同资助，佛罗里达大学的Clifford R. Bowers教授和爱荷华州立大学的Wenyu Huang教授寻求开发新的仪器和方案，以提高核磁共振（NMR）光谱的灵敏度，核磁共振（NMR）光谱是表征化学结构的组成和结构的重要方法，也是核磁共振成像的基础，核磁共振成像是医学诊断的主要工具。该团队正在开发连续流方法和先进的金属间纳米颗粒催化剂，努力将核磁共振光谱的灵敏度提高1万倍以上。该研究将通过佛罗里达大学大学预科教育和培训中心（CPET）和几个NSF本科生研究经验（REU）项目为高中生和本科生提供研究经验。在爱荷华州的艾姆斯，拓展活动还包括科学展览，让本科生和高中生参与研究活动，并结合项目概念进行演示。核磁共振（NMR）依赖于分子中核自旋能级（即自旋极化）的居群差异。在传统的核磁共振中，通过将样品置于高静态磁场中来诱导自旋极化。然而，即使在最高可用磁场下，接近环境温度的热平衡自旋极化也不大于约0.01%，因此核磁共振跃迁强度本质上是弱的。基于对苯二氢的超极化可以提供一种强大且经济高效的方法，该方法具有可扩展性，并且兼容于极化接近100%的流体中分子的快速连续生产。对于从对氢生产超极化液体，多相催化提供了关键的好处：固体催化剂可以提供一致的活性（在适当的条件下），催化剂材料可以很容易地从溶解的超极化产物中分离出来。从对氢和多相催化中推进溶液态超极化需要对分子解离后的催化机理和对氢自旋动力学有清晰的认识。通过连续流非均相催化发展对氢增强极化，将有助于对氢化反应和非氢化过程（如表面介导的对氢超极化）的潜在机制和自旋动力学的基础研究。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Chemical Measurement and Imaging (CMI) Program in the Division of Chemistry (CHE), and partial co-funding from two other CHE programs, Chemical Structures, Dynamics, and Mechanisms - A (CSDM-A) , and Chemical Catalysis (CAT) and also from the Molecular Biophysics Cluster in the Molecular and Cellular Biosciences (MCB) Division, Professors Clifford R. Bowers at the University of Florida and Wenyu Huang at Iowa State University seek to develop new instrumentation and protocols for enhancing the sensitivity of nuclear magnetic resonance (NMR) spectroscopy, an important method for characterizing the composition and structure of chemical structures and the foundation of magnetic resonance imaging – a major tool for medical diagnostics. The team is developing continuous-flow methods and advanced intermetallic nanoparticle catalysts in efforts to improve the sensitivity of NMR spectroscopy by more than a factor of 10,000. The research will provide research experiences for high school and undergraduate students coordinated through the Center for Pre-collegiate Education and Training (CPET) at the University of Florida and several NSF Research Experiences for Undergraduates (REU) programs. In Ames, Iowa, outreach activities additionally include science shows and involvement of undergraduates and high school students in research activities and demonstrations incorporating project concepts.Nuclear Magnetic Resonance (NMR) relies on population differences among nuclear spin energy levels (i.e. spin polarization) in a molecule. In conventional NMR, spin polarization is induced by placing the sample in a high static magnetic field. However, even at the highest available magnetic fields, thermal equilibrium spin polarizations near ambient temperature are no greater than about 0.01%, and hence the NMR transition intensities are inherently weak. Parahydrogen-based hyperpolarization can provide a robust and cost-effective method that is scalable and compatible with rapid and continuous production of molecules in fluids with polarizations approaching 100%. For production of hyperpolarized liquids from parahydrogen, heterogeneous catalysis offers key benefits: the solid catalysts can provide consistent activity (under appropriate conditions) and the catalyst material can be easily separated from dissolved hyperpolarization products. Advancement of solution-state hyperpolarization from parahydrogen and heterogeneous catalysis requires a clear understanding of the catalytic mechanism and parahydrogen spin dynamics after dissociation of the molecule. The development of parahydrogen-enhanced polarization by continuous-flow heterogeneous catalysis will facilitate fundamental studies of the underlying mechanisms and spin dynamics of hyperpolarization from hydrogenation reactions as well as non-hydrogenative processes such as surface-mediated hyperpolarization from parahydrogen.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.