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

Lead Research Organisation: University of Bristol
Department Name: Chemistry

Abstract

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

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/R513179/1 01/10/2018 30/09/2023
2123398 Studentship EP/R513179/1 24/09/2018 23/09/2022 Georgia Thornton