Novel Cation Radical and Exciplex Chemistry

新型阳离子自由基和激基复合物化学

• 批准号: 1464729
• 负责人: Joseph Dinnocenzo
• 金额: $ 55万
• 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: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1464729&HistoricalAwards=false
• 关键词: Novel; Cation; Radical; Exciplex; Chemistry

With this award, the Chemical Structure, Dynamics, and Mechanism B Program is supporting Professor Joseph P. Dinnocenzo at the University of Rochester to investigate the selective formation of highly reactive aryl radicals under mild conditions. The mechanistic insight gained from these studies can provide the knowledge necessary to rationally utilize the chemistry in synthesis and in the design of new materials. In addition, research on newly discovered cationic exciplexes and exciplexes that exhibit dual emissions will provide knowledge on these novel excited state intermediates. Research to better understand the fundamental photophysical properties these exciplexes intermediates will provide valuable knowledge for the design of efficient photoinduced electron transfer reactions and for potential use in sensing applications. Student co-workers will learn to carry out chemical syntheis and to conduct mechanistic studies in photochemistry. including a range of less traditional techniques (fluorometry, transient absorption spectroscopy, time-correlated single photon counting, electrochemistry, and modern computational methods). Thus, students trained with NSF support will be well prepared to tackle a variety of multidisciplinary problems in their professional, scientific careers.This project will also benefit undergraduate students through the NSF REU summer program at the University of Rochester with particular attention paid to recruiting students from groups traditionally underrepresented in science and engineering.Recent work in the Dinnocenzo laboratory has revealed that aryltrialkylstannane cation radicals undergo nucleophile-assisted fragmentation reactions in which less stable aryl radicals are often formed in preference to more stable alkyl radicals - an seemingly contrathermodynamic result. This selectivity is unprecedented in ion radical chemistry. Proposed research will test the generality of these remarkable results by exploring the fragmentation reactions of aryltrialkyl-germane and -silane cation radicals through the combined use of synthesis, steady-state photooxidation experiments, and nanosecond transient absorption spectroscopy. In addition, two types of novel, charge-transfer exciplex intermediates recently discovered in the Dinnocenzo laboratory will be investigated. One type of exciplex is formed by reaction of cationic, excited state acceptors with neutral donors, which leads to the formation of emissive cationic exciplexes that are without precedent. Research objectives include determining the electronic nature of the exciplexes (e.g. electronic coupling matrix elements) through theoretical fitting of the radiative lifetimes of the exciplexes (determined by time-correlated single photon counting) and their fluorescence spectra, exploring the generality of cationic exciplexes, and measuring some of their photophysical properties. A related project will investigate examples uncovered in the PI's lab where two exciplex emissions are observed from a single acceptor and donor. Preliminary results indicate dramatically different solvent reorganization energies for the two types of exciplexes. Proposed research will determine the electronic properties of the exciplexes and explore their generality.

有了这一奖项，化学结构，动力学和机制B计划正在支持罗切斯特大学的约瑟夫·迪诺科佐教授，以调查在温和条件下高反应性芳基自由基的选择性形成。从这些研究中获得的机械洞察力可以为合成和设计新材料的设计提供必要的知识。此外，对表现出双重排放的新发现的阳离子阳离子动力和分离物的研究将提供有关这些新型激发态中间体的知识。为了更好地理解这些动力中间体的基本光物理特性的研究将为设计有效的光诱导电子传递反应以及在感应应用中的潜在用途提供宝贵的知识。 学生同事将学会进行化学合理，并在光化学领域进行机械研究。包括一系列不太传统的技术（荧光法，瞬态吸收光谱，时间相关的单光子计数，电化学和现代计算方法）。因此，接受NSF支持培训的学生将做好充分的准备，以解决其专业的科学职业中的各种多学科问题。该项目还将通过罗切斯特大学的NSF REU夏季计划受益于本科生，并特别关注从传统上招募的学生在科学和工程学中表现出的养分培训的养分型，该培训在Dinnocenzo中表现出了不足的工作。自由基经历亲核试剂辅助的碎片反应，在这种反应中通常形成较不稳定的芳基自由基反应，而不是更稳定的烷基自由基 - 看似构成的烷基动力学结果。在离子自由基化学中，这种选择性是前所未有的。拟议的研究将通过探索合成，稳态光氧化实验以及纳米秒短暂吸收光谱的综合使用，通过探索芳基甲基甲烷和硅烷阳离子自由基的碎裂反应来检验这些显着结果的普遍性。此外，将研究两种类型的新型电荷转移Exiplex中间体，最近将研究Dinnocenzo实验室。一种类型的离心型是由阳离子，激发态受体与中性供体的反应形成的，这导致没有先例的发射阳离子脱离阳离子脱落。研究目标包括通过理论拟合分离的辐射寿命（由时间相关的单个光子计数确定）及其荧光光谱，从而确定散热器的电子性质（例如电子耦合矩阵元素），从而探索了阳离子的传感器的一般性，并测量了其phopophyssily的一般性。一个相关的项目将调查在PI实验室中发现的示例，其中从一个受体和供体中观察到了两次动力排放。初步结果表明，两种类型的动力学的溶剂重组能在急剧不同。拟议的研究将确定移植物的电子特性，并探索其通用性。