Radical Cage Effects in Organometallic Chemistry

俄勒冈大学化学与生物化学系的大卫·R·泰勒教授将研究一类被称为自由基的分子的反应性，该项目由化学系化学结构、动态与机制B项目资助。自由基参与了许多重要的化学反应和过程，包括老化、塑料制造、塑料降解、光合作用、细胞过程、太阳能转换和储存以及污染物造成的环境破坏。这项研究的目标是了解自由基是如何反应的，这样我们就可以利用它们的发展为有用的目的，并在必要时减轻它们的破坏性反应性。该项目位于有机、无机、有机金属和生物化学的界面，因此非常适合各级科学家的教育。该研究小组还致力于教育和培训在科学领域代表性不足的学生。非理科生和有兴趣向公众传播科学的学生参与的外展活动也将成为资助项目的一部分。自由基笼效应对溶液中的反应性有巨大的影响，该项目的总体目标是揭示控制自由基笼效应的基本原理，以便更好地理解和解释自由基的反应性。有机金属分子中的金属-金属或金属-碳键光解会产生自由基笼对。激光泵浦探测法和稳态辐照法将用于测量这些系统中的笼形效应。我们建议用实验来回答下列基本的、尚未得到解答的问题。1. 笼形效应用溶剂微粘度比体粘度分析更合适吗？2. 当溶剂笼中的两个自由基不相同时，自由基的质量、大小和形状对笼效应有什么影响？当这个问题的答案与在问题1的调查过程中所学到的信息相结合时，将提供一种定量预测能力，可以应用于各种不同的自由基和溶剂。3. 笼形效应是否取决于用于产生自由基的激发波长？4. 笼形效应是否受到分子上的拉应力或剪切应力的影响？

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?