Boron: Beyond the Reagent

Boron is Earth-abundant, and present in its 'mineral form' in everyday objects, such as glass, detergents, flame-retardants, preservatives, and eye-drops. Boron is also found in 'organic form' in nature, including plant enzymes, and is an essential element in the diets of numerous living species, including ourselves. Inclusion of boron in man-made ('synthetic') organic compounds, often in place of one carbon atom in a chain of carbon atoms, can impart tremendous changes in the properties of a molecule. When these 'borylated' molecules are correctly 'tuned' by having the boron in the 'right place' together with other elements such as nitrogen and oxygen - their new properties can be harnessed to provide compounds with diverse applications. These range from 'smart' materials (e.g., in thin-film displays) through to safe, 'green' and economically advantageous reagents in the production of agrochemicals and pharmaceuticals, and, in another very recently emerging application, in the drug molecules themselves.

Whilst there is no doubt that boron will continue to be a critical element in molecules and materials that are essential to our 21st century existence, the tools to install boron in, and to release boron from, such 'borylated' species have lagged behind the growth of the applications. The carbon-boron bond in borylated molecules can be fickle: on occasion it is fragile and keeping the assembly in place is the challenge. On other occasions it is too robust, resisting release of its organic molecule cargo, except under harsh conditions, where it is impossible to control the outcome. This research programme will tame these molecules to eliminate these gaps. We have assembled a world-class team that combines deep insight from experts in the design, preparation and analysis of borylated molecules, with end-user specialists who will help steer our investigations. Together, we will identify key opportunities and exploit the breakthroughs. With the market for borylated molecules expected to reach $1.7 Billion by 2025, this work will enable multi-scale applications across chemical, materials, and biological sciences, and provide a gateway to future technologies.

Three divergent, expertise-related, and cross-fertilising research areas will be tackled, directly contributing to EPSRC themes of Healthcare Technologies, Manufacturing the Future, and the Productive and Resilient Nation.

1. In developing borylated medicines, we will discover how to tune the instability of the carbon-boron bond to develop new boron-containing pharmaceuticals. These will resist carbon-boron bond cleavage until they have delivered the borylated pro-drug to the correct location, e.g., a specific organ, and then undergo cleavage to release the active drug in the right place at the right time. This will ensure the optimum concentration at the target, avoiding undesired side-effects, and requiring lower and safer doses.

2. In chemical manufacturing, we will design borylated reagents with switchable (arm/disarm) reactivity. These robust species will be easily prepared, stored and transported, on large scales if required. Yet, when ready for use, on addition of small amount of a 'release' component, the borylated reagent will rapidly switch to its reactive armed form, delivering the organic molecule payload, primed for the manufacturing process. This will reduce waste, increase safety, and allow new processes to be developed.

3. Smart boron-containing materials, used in devices such as OLEDs, need to be able to deliver efficient function and stability over long device lifetimes. This necessitates very high stability in the carbon-boron bond for these applications. We will design and test new borylated building blocks that are immune to 'release' of the organic fragment, under a wide range of operating conditions. This will broaden the conditions that the devices will tolerate and increase their application scope.