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项目的支持下，罗切斯特理工学院的Michael Kotlarchyk教授及其同事乔治Thurston和Pratik 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，分子组装体和溶液的结构和动力学。 基于核磁共振（NMR）和极化中子散射（PNS）组合的目标技术有可能彻底改变各种材料的详细分子尺度信息，包括液体混合物，催化剂，纳米材料和生物大分子。所获得的信息对于预测和合理化工业，医疗和社会重要性的许多过程至关重要。PI积极参与旨在提高来自代表性不足群体的学生参与STEM的计划，以参与跨学科的最先进的研究。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NMR-PNS的量子力学密度算子治疗，以治疗自旋弛豫，自旋耦合以及任何量子自旋的原子核的结合。这将使预测和模拟的PNS横截面和信噪比的超极化分子在溶液中，并通过专门的NMR协议制备的分子。分子动力学模拟超极化的分子在溶液中通过信号放大可逆交换（SABRE）正在进行，以允许在溶液中，这是必不可少的预测的PNS信号和严格的统计分析PNS信号噪声的站点-站点的空间相关性的定量评价。 将设计和模拟将选择性脉冲整形和测序应用于超极化分子的NMR协议，从而能够使用相关函数来评估所得的极化中子散射截面。最后，将对SABRE-hyperpolarized分子的推定NMR-PNS方案进行完整的统计分析。模拟的散射信号将为有效的NMR-PNS仪器和实验的设计提供信息，包括样品环境、光束线和探测器参数。最终目的是确定通过NMR自旋操纵选择的原子对之间的结构因子，从亚埃到微米的长度尺度，从而提供有关溶液中分子构象和相对取向的有价值的信息。即将开发的SABRE-PNS方法是迈向全面的NMR-PNS的重要垫脚石，其本身将是有价值的。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 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.