UCLA

Through years of development and refinement, solid-state photochemistry has been proven to be a powerful tool in many fields of science. This is because in comparison to solution-state photochemistry, molecules that react in the solid-state are trapped in their crystal cavity, which limits the number of reactive chemical pathways that these reactants are able to explore. In many cases, this phenomenon induces desirable reaction characteristics such as high stereospecificity and regiospecificity and high product yield due to the minimal formation of side products. However, the utility of solid-state photochemistry has been limited because of a lack of readily accessible methods to analyze and observe reactions in the solid-state. Although literature precedence reveals significant efforts to understand the mechanistic aspects of solid-state photochemical reactions, primarily by comparison of crystallographic data of the reactants and products, the use pulsed-laser techniques to analyze the formation of excited states and transient intermediates is currently limited by challenges arising from the optical properties of bulk solids. Therefore, in order to develop a more powerful method to extract kinetic information of photochemical solid-state reactions, our research group has developed the use nanocrystalline suspensions as a means to overcome the physical limitations of bulk solids. We have shown that nanocrystals suspended in water approach the properties of supramolecular systems and reduce many of the challenges associated with the high optical densities, light scattering and birefringence of solids. By taking advantage of a one way flow system the use of nanocrystalline suspension also limits the potential interference from photoproduct build up. Thus, in order to further elucidate a useful method for determining kinetic information, this dissertation offers a novel perspective to enhance the field of solid-state photochemistry via reporting the photochemistry and kinetic analysis of various a-phenyl substituted ketones in solution and in nanocrystalline suspensions.