A New Class of Hybrid Polyoxometalate Catalysts for C-H Functionalisation

Lead Research Organisation: University of Nottingham
Department Name: Sch of Chemistry


Many decades of research in chemical synthesis have provided numerous new reactions to prepare molecules required by society, such as pharmaceuticals, agrochemicals, and materials. At the forefront of modern synthesis is late-stage catalytic C-H functionalisation (LSF), which can be faster and more efficient for producing libraries of diverse compounds compared with conventional synthetic approaches, where diversification occurs at an early stage and more highly functionalised substrates are required.

However, despite numerous advances, significant challenges remain. The majority of LSF reactions occur at positions dictated by the intrinsic reactivity of the substrates, defined on the basis of steric and/or electronic factors. The ability to override intrinsic substrate reactivity to functionalise at "unexpected" sites in a controllable and switchable manner, is an ongoing challenge.

Key to making advances in this area is the development of fundamentally new types of catalysts operating on unique design principles to override intrinsic substrate reactivity and control site-selectivity. In particular, harnessing a wide range of non-covalent and dynamic covalent interactions to bind and orient substrates to expose one particular site towards the reactive part of the catalyst will be required.

In this project, we propose to develop a new class of catalysts for highly site-selective C-H functionalisation, using photochemical activation. Polyoxometalate clusters will be modified with organic groups to give organic-inorganic hybrids containing substrate binding units to coordinate and orient substrates to override intrinsic reactivity. These new hybrid catalysts will be used for diverse C-H functionalisation reactions of a wide range of compounds, such as steroids and peptides. The preparation of chiral catalysts to enable the synthesis of chiral products enriched in one particular enantiomer (non-superimposable mirror image) will also be investigated.

We hope this research will enable the development of increasingly more versatile and efficient catalysts for chemical synthesis.


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Description Polyoxometalates (POMs) are polyanionic molecular metal oxide clusters with diverse structures and versatile chemical properties, which make them attractive components for incorporation into a range of hybrid, soft, and nanoscale materials. In some cases, they can also be modified with organic fragments to yield organic-inorganic hybrid POMs. These systems can be rationally designed to exhibit particular chemical and structural properties.

This project has developed methods to access a new class of organic-inorganic hybrid POMs. Specifically, we have prepared Wells-Dawson POMs functionalised with a range of diphosphoryl groups. The redox potentials of the new POMs were found to be significantly impacted by the nature of the diphosphoryl group. In addition, compared with existing phosphonate-hybridised Wells-Dawson POMs, they offer a wider tunable redox window and enhanced stability in aqueous solvent systems.

Ongoing work is aimed at developing additional new classes of hybrid POMs and their use in diverse applications, including as photocatalysts for organic reactions.
Exploitation Route This work will be of interest to researchers engaged in the development of new functional materials and catalysts.
Sectors Chemicals