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Ultrafast spectroscopy studies of photoredox catalysed reaction mechanismsUltrafast spectroscopy studies of photoredox catalysed reaction mechanisms

光氧化还原催化反应机理的超快光谱研究光氧化还原催化反应机理的超快光谱研究

基本信息

批准号：
2123398
负责人：
金额：
--
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2018
资助国家：
英国
起止时间：
2018 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-2123398
关键词：
Ultrafast spectroscopy studies photoredox catalysed

项目摘要

Many applications of chemistry use catalysis to enhance the rates and efficiencies of critical reaction steps, but refinement of catalyst design and development of new catalytic methods require a deep understanding of their mechanisms of reaction. Catalytic cycles are made up of a sequence of steps that can occur on timescales from femtosecond through to millisecond or longer, spanning more than 10 orders of magnitude of time. These individual steps involve reactive intermediates which can be difficult to isolate, but which must be identified for a complete understanding of the reaction mechanism. This research project will use advanced ultrafast spectroscopy techniques to observe the sequence of steps in photo-initiated catalytic cycles in solution, from catalyst activation on sub-picosecond timescales to completion of reactions. Transient features in infra-red and ultraviolet/visible absorption spectra will identify the intermediate species, measure the timescales for their production and loss, characterize solvent-solute interactions which influence catalyst performance at the molecular level, and build a comprehensive picture of complete catalytic pathways.The research will focus on photoredox catalysis, which is transforming chemical synthesis. Photoredox catalysts use visible and near-UV light to initiate chemical transformations under mild conditions. Transient absorption spectroscopy measurements will seek to observe the complete cycle of steps from UV excitation of the photoredox catalyst to bimolecular radical reactions initiated by electron transfer, and ultimately to recovery of the catalyst. The outcomes will identify the properties of the molecular photocatalysts which control their performance, and will direct the optimized design of organic photocatalysts for sustainable future applications including the synthesis of molecules and materials with numerous medicinal and technological applications

许多化学应用使用催化来提高关键反应步骤的速率和效率，但催化剂设计的改进和新催化方法的开发需要对其反应机理有深入的了解。催化循环由一系列步骤组成，这些步骤可以在飞秒到毫秒或更长时间尺度上发生，跨越10多个数量级的时间。这些单独的步骤涉及难以分离的反应中间体，但必须对其进行识别才能完全理解反应机理。该研究项目将使用先进的超快光谱技术来观察溶液中光催化循环的步骤序列，从亚皮秒时间尺度的催化剂激活到反应完成。红外和紫外/可见吸收光谱中的瞬态特征将识别中间物质，测量它们产生和损失的时间尺度，在分子水平上表征影响催化剂性能的溶剂-溶质相互作用，并建立完整催化途径的全面图景。研究将集中在光氧化还原催化，这是改变化学合成。光氧化还原催化剂利用可见光和近紫外光在温和条件下引发化学转化。瞬态吸收光谱测量将寻求观察从光氧化还原催化剂的紫外激发到由电子转移引发的双分子自由基反应，并最终恢复催化剂的完整循环步骤。研究结果将确定控制其性能的分子光催化剂的性质，并将指导有机光催化剂的优化设计，以实现可持续的未来应用，包括具有许多医学和技术应用的分子和材料的合成