Mechanistic Investigations on Group 14 Cation Radical Reactions

14族阳离子自由基反应的机理研究

• 批准号: 0749919
• 负责人: Joseph Dinnocenzo
• 金额: $ 36.9万
• 依托单位: University of Rochester
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-01 至 2011-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0749919&HistoricalAwards=false
• 关键词: Mechanistic; Investigations; Group; 14; Cation

With the support of the Organic and Macromolecular Chemistry Program, Professor Joseph Dinnocenzo's proposed research will provide fundamental mechanistic insight into the structures, reactivities, and reaction mechanisms of group 14 cation radical intermediates. This knowledge will establish a foundation for understanding experimental observations. The research will also provide the predictive power needed to successfully utilize ion radicals for new chemical processes in synthesis and in materials applications.The proposal has four primary research goals:(1)Generate reactive cation radicals of organo-silanes, -germanes, -stannanes, and plumbanes, and use nanosecond and picosecond transient absorption techniques to elucidate the mechanism(s) for their reactions with nucleophiles. For nucleophile assisted mechanisms they will apply additional tests, recently developed in the PI's laboratory, to distinguish between concerted and stepwise pathways.(2)Determine the stereochemical course of nucleophilic substitutions on Group 14 cation radicals using the endocyclic restriction test.(3)Perform critical mechanistic experiments to test recent molecular orbital calculations in their laboratory that predict reversible nucleophilic substitutions for some organosilane cation radical/nucleophile pairs. If confirmed, the chemistry may lead to a new experimental method for generating cation radical intermediates.(4)Investigate the fragmentation mechanisms of oligosilane cation radicals as models for polysilane cation radicals, which have been proposed as reactive intermediates produced during the photolysis of polysilane photoresists.Broader Impacts. Organic ion radical chemistry is still in its infancy in comparison with that of a variety of other reactive intermediates (e.g. carbocations, carbanions, free radicals, and carbenes). There remains a great deal to learn about ion radical chemistry and its potential applications (e.g. in synthetic and materials chemistry). History has shown that progress toward such practical goals is facilitated and accelerated by mechanistic understanding. One of the goals of this proposal is to provide such understanding. The proposed research will also provide an usually rich educational experience for students. For example, in addition to learning mechanistic methodologies, students will learn how to synthesize, purify, and spectroscopically characterize compounds. Students will also receive training in a range of less traditional techniques (transient absorption spectroscopy, time resolved single photon counting, electrochemistry, and modern computational chemistry. This proposal will also benefit undergraduate students and high school teachers through the NSF REU RET summer program at the University of Rochester. Over the past 10 years, the PI has, on average, hosted 2 summer visitors/year through this program. Nearly half of these visitors have been from groups underrepresented in science and engineering. Summer visitors learn through research and through a summer minicourse on photoinduced charge transfer co-taught by the PI.

在有机和大分子化学计划的支持下，Joseph Dinnocenzo教授提出的研究将为第14组阳离子自由基中间体的结构，反应活性和反应机制提供基本的机理见解。 这些知识将为理解实验观察奠定基础。 该研究还将提供成功利用离子自由基在合成和材料应用中的新化学过程所需的预测能力。该提案有四个主要研究目标：（1）产生有机硅烷、锗烷、锡烷和铅烷的反应性阳离子自由基，并使用纳秒和皮秒瞬态吸收技术阐明它们与亲核试剂反应的机理。 对于亲核试剂辅助机制，他们将应用PI实验室最近开发的额外测试，以区分协调和逐步途径。（2）用环内限制试验确定14族阳离子自由基上亲核取代的立体化学过程。（3）进行关键的机械实验，以测试他们实验室中最近的分子轨道计算，预测一些有机硅烷阳离子自由基/亲核试剂对的可逆亲核取代。 如果得到证实，化学可能导致一个新的实验方法产生阳离子自由基中间体。（4）研究作为聚硅烷阳离子自由基模型的低聚硅烷阳离子自由基的断裂机制，聚硅烷阳离子自由基被认为是聚硅烷光致抗蚀剂光解过程中产生的活性中间体。有机离子自由基化学与其他活性中间体（如碳正离子、碳负离子、自由基和卡宾）相比仍处于起步阶段。 关于离子自由基化学及其潜在应用（例如在合成和材料化学中），还有很多东西需要学习。 历史已经表明，机械的理解促进和加速了实现这些实际目标的进展。 本提案的目标之一就是提供这种理解。拟议的研究还将为学生提供通常丰富的教育经验。 例如，除了学习机械方法，学生将学习如何合成，纯化和光谱表征化合物。 学生还将接受一系列不太传统的技术（瞬态吸收光谱，时间分辨单光子计数，电化学和现代计算化学）的培训。该提案还将通过罗切斯特大学的NSF REU RET暑期项目使本科生和高中教师受益。 在过去的10年里，PI平均每年通过该计划接待2名夏季访问者。 这些访客中有近一半来自科学和工程领域代表性不足的群体。 夏季游客通过研究和PI共同教授的光致电荷转移夏季迷你课程学习。