High-Resolution Crystallographic Studies of Short-lived Excited State and Structural Dynamics in Solids

通过这项由化学系化学结构、动力学和机制计划资助的奖项，菲利普·科彭斯教授和他的团队将开发和应用X射线衍射方法来详细研究固体中的光诱导过程。化学通常被称为一门研究分子变化的科学；因此，对反应机理的研究是化学的中心。这些研究旨在增加我们对光转化为化学能的光化学过程的理解。这项研究使用结晶学、光谱学和理论计算相结合的方法来研究发生在纯晶体或多组分、骨架形成的超分子固体中的化学反应。这些超分子固体提供了极大的通用性，因此有机会观察分子环境对反应性的影响。这包括晶体基质施加的空间位阻对反应速率和产物构象的影响，腔壁的手性对产物性质的影响，以及根据转移的方向可以增强或抑制反应活性的主客体能量转移的效果。这项工作的一个特别活跃的组成部分是对固体中光诱导的短暂物种的研究。这种物种只存在百万分之一秒或更短的时间，但它们决定了随后的化学反应过程，在材料化学中至关重要。在原子水平上研究化学反应活性与我们理解化学反应是如何进行和可以操纵有关。这些反应包括重要的催化、固态和生理过程。该项目涉及科学的前沿领域--固态化学，世界各地的许多实验室都在进行这一领域的研究。它的目标之一是保持美国在这一领域的竞争力。

Through this award, funded by the Chemical Structure, Dynamics, and Mechanisms Program of the Division of Chemistry, Professor Philip Coppens and his team will develop and apply X-ray diffraction methods for the detailed study of photo-induced processes in solids. Chemistry is often referred to as a science of molecular change; studies of reaction mechanism are therefore central to chemistry. The studies are designed to increase our understanding of photo-chemical processes in which light is converted into chemical energy. The research uses a combination of crystallography, spectroscopy and theoretical calculations to study chemical reactions which take place in either pure crystals or in multi-component, framework-forming, supramolecular solids. These supramolecular solids offer great versatility and therefore the opportunity to observe the effect of the molecular environment on reactivity. This includes the influence of steric restrictions imposed by the crystal matrix on the reaction rate and the conformation of the product, the effect of the chirality of the cavity walls on the nature of the product, and the effect of host-guest energy transfer which can enhance the reactivity or suppress it, depending on the direction of the transfer. A particularly active component of the work is the study of light-induced fleeting species in solids. Such species exist for a millionth of a second or less, but determine the course of subsequent chemical reactions and are of crucial importance in materials chemistry.The study of chemical reactivity at the atomic level is relevant for our understanding of how chemical reactions proceed and can be manipulated. Such reactions include important catalytic, solid state and physiological processes. The project concerns a frontier area of science, solid-state chemistry, which is pursued in many laboratories across the world. One of its aims is to keep the United States competitive in the field.