Development and Application of Size and Charge Resolved NMR

位于查佩尔山的北卡罗来纳州大学的Charles约翰逊在实验物理化学计划的支持下，继续开发基于分子大小和电荷的扩散有序和迁移率有序NMR方法。 一个主要的努力将是针对实现环形腔检测器（TCD）的高分辨率NMR结合成像的扩散和流动。 实验和计算机模拟将被用来调查表现的静态场的不均匀性，非共振效应，不完全放松，和辐射阻尼是独特的TCD图像和线形。 传统和TCD方法将集中在两个合作应用：（1）特别设计的表面活性聚合物在液体和超临界二氧化碳中的相互作用的研究，和（2）最近合成的可分离的，水溶性的金簇的硫普罗宁单层保护的研究。第一组实验的动机是液体/超临界二氧化碳作为聚合反应的溶剂体系的日益重要性，这是由环境驱动的逐步淘汰氯氟烃，以避免挥发性有机化合物的排放，并减少含水废物流所产生的。 第二组实验提供了电泳NMR方法的试验场，以及有机会模拟粒子的电动力学性质，其中核心半径，配体层厚度和多分散性程度可以变化。 该项目涉及使用核磁共振光谱法开发新实验，以及将这些新技术应用于重大化学问题。 环境友好的二氧化碳作为聚合物合成和清洁过程的溶剂越来越重要，该项目的成果将提高对液体和超临界二氧化碳有效实际使用所需的理解。 由有机化合物单分子膜保护的金团簇在纳米电子器件、化学传感器和生物传感器中具有潜在的应用，本研究将为这些团簇系统的性质提供见解。

Charles Johnson of the University of North Carolina at Chapel Hill is supported by the Experimental Physical Chemistry Program to continue the development of diffusion ordered and mobility ordered NMR methods for the resolution of molecules on the basis of molecular size and charge. A major effort will be directed toward implementing toroid cavity detectors (TCDs) for high resolution NMR combined with imaging of diffusion and flow. Experiments and computer simulations will be used to investigate manifestations of static field inhomogeneities, off-resonance effects, incomplete relaxation, and radiation damping that are unique to TCD images and line shapes. Both traditional and TCD methods will be focused on two collaborative applications: (1) studies of interactions of specially designed surface active polymers in liquid and supercritical carbon dioxide, and (2) studies of recently synthesized isolable, water soluble gold clusters protected by monolayers of tiopronin. The first set of experiments is motivated by the growing importance of liquid/supercritical carbon dioxide as a solvent system for polymerization reactions resulting from the environmentally driven needed to phase out chlorofluorocarbons, to avoid emission of volatile organic compounds, and to reduce aqueous waste streams. The second set of experiments provides a testing ground for electrophoretic NMR methods as well as the opportunity to model electrokinetic properties of particles in which core radius, layer thickness of ligands, and degree of polydispersity can be varied. This project involves the development of novel experiments using nuclear magnetic resonance spectroscopy, and the application of these new techniques to significant chemical problems. Environmentally benign carbon dioxide is growing in importance as a solvent for polymer synthesis and cleaning processes, and outcomes from this project will enhance the understanding needed for effective practical use of liquid and supercritical carbon dioxide. Gold clusters protected by monolayers of organic compounds have potential applications in nanoscale electronic devices, chemical sensors, and biosensors, and the present studies will provide insights into the properties of these cluster systems.