CDS&E: Combining Nuclear Magnetic Resonance and Neutron Scattering for Determining Macromolecular and Liquid Structure: Towards Development of the Novel NMR-PNS Technique

在化学系化学测量和成像计划的支持下，罗切斯特理工学院的Michael Kotlarchyk教授及其同事George瑟斯顿和Patik Dholabhai正在为开发一种强大的下一代技术奠定基础，以探测分子、分子组装和解决方案的结构和动力学。这项基于核磁共振(核磁共振)和极化中子散射(PNS)相结合的靶向技术，有可能彻底改变可用于各种材料的详细的分子尺度信息，包括液体混合物、催化剂、纳米材料和生物大分子。要获得的信息对于预测和合理化许多具有工业、医疗和社会重要性的过程至关重要。PIS积极参与旨在加强STEM参与的项目，这些学生来自代表不足的群体，参与跨学科的最新研究。该项目侧重于计算建模，作为未来实验方法发展的基础。该团队正在扩展核磁共振-PNS的量子力学密度算符处理，以处理自旋松弛、自旋耦合和原子核与任何量子自旋的结合。这将使得能够预测和模拟溶液中超极化分子和通过专门的核磁共振协议制备的分子的PNS截面和信噪比。对溶液中通过可逆交换信号放大(SABRE)而超极化的分子进行了分子动力学模拟，以实现对溶液中位置-位置空间相关性的定量评估，这对于预测PNS信号和严格的PNS信噪比统计分析是必不可少的。将设计和模拟对超极化分子应用选择性脉冲整形和排序的核磁共振协议，从而能够使用关联函数来评估所产生的极化中子散射截面。最后，将对军刀超极化分子可能的核磁共振-PNS方案进行完整的统计分析。模拟的散射信号将为设计有效的核磁共振-PNS仪器和实验提供信息，包括样品环境、光束线和探测器参数。其最终目的是确定通过核磁共振自旋操纵选择的原子对之间的结构因子，从亚埃到微米尺度，从而提供关于分子构象和溶液中相对取向的有价值的信息。将要开发的SABRE-PNS方法是迈向全面核磁共振-PNS的重要垫脚石，本身将是有价值的。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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 Program in the Division of Chemistry, Professor Michael Kotlarchyk and colleagues George Thurston, and Pratik Dholabhai at Rochester Institute of Technology are laying the groundwork for development of a powerful next-generation technique to probe structures and dynamics of molecules, molecular assemblies, and solutions. The targeted technique, based on a combination of Nuclear Magnetic Resonance (NMR) and Polarized Neutron Scattering (PNS), has the potential to revolutionize the detailed, molecular-scale information available for a broad variety of materials, including liquid mixtures, catalysts, nanomaterials, and biological macromolecules. The information to be gained is crucial for predicting and rationalizing many processes of industrial, medical, and societal importance. The PIs are actively engaged in programs seeking to enhance STEM engagement by students from underrepresented groups, for involvement in interdisciplinary state-of-the-art research.The project focuses on calculational modeling as a foundation for future development of experimental methods. The team is extending the quantum-mechanical density-operator treatment of NMR-PNS to treat spin relaxation, spin coupling, and the incorporation of nuclei with any quantum spin. This will enable the prediction and simulation of PNS cross sections and signal-to-noise ratios for hyperpolarized molecules in solution and for molecules prepared via specialized NMR protocols. Molecular dynamics simulations of molecules hyperpolarized in solution via Signal Amplification by Reversible Exchange (SABRE) are being undertaken to permit quantitative evaluations of site-site spatial correlations in solution, which are essential for predicting the PNS signal and for a rigorous statistical analysis of PNS signal-to-noise. NMR protocols that apply selective pulse-shaping and sequencing to hyperpolarized molecules will be designed and simulated, thereby enabling use of the correlation functions to evaluate the resulting polarized neutron scattering cross-sections. Finally, complete statistical analyses of putative NMR-PNS protocols for SABRE-hyperpolarized molecules will be performed. The simulated scattering signals will inform the design of effective NMR-PNS instrumentation and experiments, including sample environment, beamline, and detector parameters. The ultimate aim is to determine structure factors between atomic pairs selected via NMR spin-manipulation, from sub-angstrom to micron length scales, thereby giving valuable information about molecular conformations and relative orientations in solution. The SABRE-PNS methods to be developed are important stepping-stones toward full NMR-PNS and will be valuable in their own right.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.