Radical Cage Effects in Organometallic Chemistry

在这个由化学系化学结构、动态和机理B计划资助的项目中，俄勒冈大学化学和生物化学系的David R Tyler教授将研究一类被称为自由基的分子的反应性。自由基与许多重要的化学反应和过程有关，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激进分子是如何反应的，以便我们能够利用它们的发展达到有用的目的，并在必要时减轻它们的破坏性反应。该项目位于有机、无机、有机金属和生物化学的交界处，因此非常适合各级科学家的教育。这个研究小组还坚定地致力于教育和培训在科学方面代表性不足的学生。涉及非理科专业学生和对向公众传播科学感兴趣的学生的外展活动也将是该资助项目的一部分。自由基笼子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支配自由基笼子效应的基本原理，以便更好地理解和解释激进的反应性。有机金属分子中金属-金属或金属-碳键的光解将产生自由基笼对。激光泵浦探测法和稳态照射法将被用来测量这些系统中的笼状效应。我们建议用实验来回答下列尚未回答的基本问题。1.用溶剂的微观粘度分析笼子效应比用体积粘度分析笼子效应更合适吗？2.在溶剂笼子中的两个自由基不同的体系中，自由基的质量、大小和形状对笼子效应有什么影响？这个问题的答案与在调查问题1期间获得的信息相结合，将提供一种定量预测能力，可应用于各种不同的自由基和溶剂。3.笼子效应是否依赖于用于产生自由基的激发波长？4.笼子效应是否受到分子上的张应力或剪应力的影响？

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?