Radical Cage Effects in Organometallic Chemistry

点击翻译按钮获取中文摘要

In this project funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division, Professor David R Tyler of the Department of Chemistry and Biochemistry at the University of Oregon will investigate the reactivity of a class of molecules known as radicals. Radicals are implicated in many important chemical reactions and processes including aging, plastics manufacturing, plastics degradation, photosynthesis, cellular processes, solar energy conversion and storage, and the environmental damage caused by pollutants. The goals of this research are to understand how radicals react so that we can exploit their development for useful purposes and, when necessary, mitigate their damaging reactivity. The project lies at the interface of organic, inorganic, organometallic, and biochemistry and is therefore well suited to the education of scientists at all levels. This research group also has a strong commitment to the education and training of students underrepresented in science. Outreach activities involving non-science majors and students interested in communicating science to the public will also be part of the funded project. Radical cage effects have an enormous impact on reactivity in solution, and the overall goal of the project is to uncover the underlying principles that govern radical cage effects so radical reactivity can be understood and interpreted better. Radical cage pairs will be generated by photolysis of metal-metal or metal-carbon bonds in organometallic molecules. Both laser pump-probe methods and steady-state irradiation methods will be used to measure the cage effects in these systems. Experiments are proposed to answer the following fundamental, as yet unanswered, questions. 1. Are cage effects more properly analyzed using solvent microviscosity rather than bulk viscosity? 2. What are the effects of radical mass, size, and shape on the cage effect in systems in which the two radicals in the solvent cage are not identical? The answer to this question, when combined with the information learned during the investigation of question 1, will provide a quantitative predictive capability that can be applied to a wide variety of different radicals and solvents. 3. Does the cage effect depend on the excitation wavelength used to generate the radicals? 4. Is the cage effect affected by tensile or shear stress on a molecule?