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Details of Grant 

EPSRC Reference: EP/P015735/1
Title: PASSE: Photochemical Amplification of Signal for Structure Elucidation
Principal Investigator: Day, Dr IJ
Other Investigators:
Osborne, Dr MA
Researcher Co-Investigators:
Project Partners:
Department: Sch of Life Sciences
Organisation: University of Sussex
Scheme: Standard Research
Starts: 01 June 2017 Ends: 31 May 2020 Value (£): 432,715
EPSRC Research Topic Classifications:
Analytical Science
EPSRC Industrial Sector Classifications:
No relevance to Underpinning Sectors
Related Grants:
Panel History:
Panel DatePanel NameOutcome
24 Jan 2017 EPSRC Physical Sciences - January 2017 Announced
25 Oct 2016 EPSRC Physical Sciences - October 2016 Deferred
Summary on Grant Application Form
Determining the connectivity of atoms in a molecule is a key task when identifying unknown compound. These compounds may arise from natural sources (e.g. plant extracts) or be the products, desired or otherwise, of a chemical reaction. Nuclear magnetic resonance (NMR) spectroscopy is one of the key techniques available to perform this identification in the solution state. Unfortunately, NMR spectroscopy is an inherently insensitive technique due to the weak interaction of nuclear spins with an applied magnetic field. This provides a lower limit on the amount of sample required to obtain quality spectroscopic data in a reasonable time frame.

This proposal will apply a photochemical nuclear hyperpolarisation method which is capable of increasing the sensitivity of an NMR experiment by over 10-fold under favourable conditions thereby improving the sensitivity of NMR spectroscopy for structure elucidation. This method relies on a spin-state selective photochemical reaction between a photosensitiser dye molecule and the compound of interest. This reaction generates a spin-correlated radical pair, where the overall spin state is well defined. After undergoing coherent oscillation between singlet and triplet states, recombination of the radical pair via the singlet channel results in significant non-Boltzmann spin population in the products, which is detected an a large signal enhancement in the NMR spectrum.

This proposal will develop a low-cost illumination device, based on high current light emitting diode arrays, in order to generate photochemical nuclear hyperpolarisation. This will then be used to develop photochemically-enhanced NMR experiments for small molecule structure elucidation. Initial focus will be on H-X correlation experiments through both one and multiple bonds. These experiments allow the atomic connectivities to be determined using less material than currently achievable. Modern approaches such non-uniform sampling will be employed to optimise the data acquisition along wit extensions to time-shared acquisition in which multiple heteronuclear correlation experiments are acquired in a single experiment. Ultimately, determination of the carbon-carbon connectivities is required to define the configuration of a molecule. Most modern experiments obtain this information indirectly via mutual correlations with hydrogen atoms. An experiment, known by the acronym INADEQUATE provides the carbon-carbon connectivities directly. Despite being proposed over 30 years ago, it has not found wide spread use due to being extremely insensitive as it detects the less than 0.01% of molecules which contain two adjacent carbon-13 atoms. The final part of this proposal will be to "rehabilitate" the INADEQUATE experiment by using photochemical enhancement and enabling its more routine use in the toolbox of NMR spectroscopic experiments.

Key Findings
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Potential use in non-academic contexts
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Date Materialised
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Further Information:  
Organisation Website: http://www.sussex.ac.uk