Rapid Kinetics by Stopped-Flow NMR

来自分析和表面化学计划的资金支持威斯康星州麦迪逊大学的Clark Landis教授使用核磁共振（NMR）光谱研究快速化学反应动力学的努力。 该研究通过探索停流NMR技术的所有关键要素，将NMR光谱学的信息丰富性与快速动力学能力相结合：理论，计算建模，探针构建和评估以及化学反应的应用。探针建设活动的重点是结合停流反应技术与流动核磁共振能力。 亥姆霍兹线圈和环形腔谐振器正在开发中，其目标是降低反应半衰期的范围。100秒到几毫秒。这两种类型的流量探头将配备实用的驱动系统和处理空气敏感试剂的能力。实际实现停流NMR功能需要了解光谱如何受到反应动力学和各种人为因素的影响。根据任意动力学模型模拟和拟合实验数据的计算程序正在开发、验证和传播。 停流核磁共振的力量是通过快速催化过程的动力学研究，如金属催化烯烃聚合，因为核磁共振方法可以普遍应用，所提出的研究的影响跨越不同的动力学过程，如蛋白质折叠，催化转化（如酶，有机金属，或有机催化），和其他化学反应。 本研究的成果包括（1）教育研究界关于NMR研究快速反应的能力的出版物，（2）模拟快速反应的NMR光谱的软件方法，（3）基于流动探针的调整或新环形腔的构造的新NMR探针的详细计划和性能评估，以及（4）关于化学动力学和NMR方法的新课堂材料。人力资源的发展，主要是本科和博士后研究人员，结果从亲密接触到一个异常广泛的研究问题，从电子到流动动力学和化学催化。

Funding from the Analytical and Surface Chemistry Program supports the efforts of Professor Clark Landis of the University of Wisconsin at Madison to study fast chemical reaction kinetics using nuclear magnetic resonance (NMR) spectroscopy. The research merges the information-rich nature of NMR spectroscopy with fast kinetics capabilities by exploring all critical elements of a stopped-flow NMR technique: theory, computational modeling, probe construction and evaluation, and application to chemical reactions. Probe construction activities focus on combining stopped-flow reaction technology with flow NMR capabilities. Both Helmholtz coil and toroid cavity resonators are being developed with the goal of lowering the range of accessible reaction half-lives from ca. 100 seconds to a few milliseconds. Both types of flow probe will be fitted with practical drive systems and the ability to handle air sensitive reagents. Practical realization of stopped-flow NMR capabilities requires understanding of how the spectra are affected by reaction kinetics and various artifacts. Computational procedures for simulation and fitting of experimental data according to any arbitrary kinetic model are being developed, verified, and disseminated. The power of stopped-flow NMR is illustrated by kinetic studies of fast catalytic processes such as metal-catalyzed alkene polymerization.Because the NMR method can be applied generally, impact of the proposed research spans diverse kinetic processes such as protein folding, catalytic transformations (such as enzymatic, organometallic, or organocatalytic), and other chemical reactions. Products of this research include (1) publications that educate the research community on the capabilities of NMR for studying fast reactions, (2) software methods for simulating NMR spectra of fast reactions, (3) detailed plans and performance evaluations of new NMR probes based on adaptation of flow probes or construction of new toroid cavities, and (4) new classroom materials concerning chemical kinetics and NMR methods. The development of human resources, primarily undergraduate and postdoctoral researchers, results from intimate exposure to an unusually broad array of research issues, ranging from electronics to flow dynamics and chemical catalysis.