High-Resolution Crystallographic Studies of Chemical Reactions and Electron Distributions in Solids
Coppens, Philip Principal Investigator
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In this project supported by the Experimental Physical Chemistry Program, Professor Philip Coppens and his team will develop 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. The latter 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. Concurrent with these activities, the Coppens group will continue development of the University at Buffalo Databank of transferable aspherical atoms,including application of aspherical atom scattering factors, their use in the calculation of the electrostatic component of intermolecular interactions beyond the point charge model, and charge density analysis of complexes with controversial bonding situations. The study of chemical reactivity at the atomic level is relevant for our understanding of chemical reaction mechanisms in general including catalytic and physiological important processes. The project concerns a frontier area of science which is pursued in many laboratories across the world. One of its aims is to keep the US competitive in the field.