Next Generation Photocatalysts for C-H Functionalisation
Lead Research Organisation:
University of Nottingham
Department Name: Sch of Chemistry
Abstract
The fundamental goal of this collaborative research project is the development of synthetic methodologies that will allow for the efficient construction of medicinally relevant compounds from simple, readily available starting materials. In this context, the project involves the design and synthesis of novel photocatalysts that can be exploited in synthetic organic reactions. Harnessing light to promote reactivity can be viewed as a more sustainable and economic energy source when compared to conventional methods such as heat and can be used to overcome significant reaction barriers. The most used catalysts in organic photoredox chemistry involve transition-metal complexes comprised of iridium, rhodium, or ruthenium. However, these platinum-group metals are rare, expensive, and usually require pre-functionalised starting materials for the reactions to proceed. In recent years, the development of catalysts that avoid these metals have shown promise in this field. However, these catalysts have limitations including low selectivity and the requirement of high energy UV-light. Furthermore, the reactions developed using these catalysts can be low yielding, be limited in scope and display competitive product decomposition. Crucial to progressing in this area is the development of novel visible light responsive photocatalysts that can be modified to (i) enhance the catalytic efficiency, (ii) exhibit additional functionality - that can be used to facilitate catalyst isolation and/or recycling, and (iii) increase the reaction rates and yield. This has sparked the drive towards more sustainable, tuneable, and selective visible-light active photocatalysts that can be used in synthetic organic reactions.
In terms of organic reaction types, particular attention will be focused on photocatalytic C-H functionalisation for this project. Couplings through C-H bond functionalisation involves the use of simple substrates that are directly converted into more complex molecules, without the need of a previous functionalisation, thus considerably reducing waste generation and the number of synthetic steps required. By combining C-H functionalisation and photoredox catalysis, established synthetic methodology could be applied and incorporated into drug discovery, as part of structure-activity relationship (SAR) exploration and late-stage functionalisation.
Proposed solution and methodology
The successful design and synthesis of a variety of photoactive catalysts forms the basis of this project. The type of catalyst we endeavour to synthesise consists of a core structure functionalised with a variety of organic ligands. By careful design, we aim to investigate the effect of different ligands on the photocatalytic performance of the catalyst, taking into consideration the effects on selectivity, yield, catalytic recycling, and efficiency of the reactions conducted. After the demonstration of the catalytic performance of the photocatalysts and insight is gained into the chemical reactivity and applicability of the catalysts, the next aim of the project involves the development of novel methodology exploiting the catalysts to their full potential. The successful completion of these aims will firstly advance existing reactions that have limitations inherent with the specific catalysts used previously, and secondly, will provide access to currently unknown or inaccessible reaction routes, allowing simple organic substrates to be converted into complex structures, under mild and efficient reaction conditions.
In terms of organic reaction types, particular attention will be focused on photocatalytic C-H functionalisation for this project. Couplings through C-H bond functionalisation involves the use of simple substrates that are directly converted into more complex molecules, without the need of a previous functionalisation, thus considerably reducing waste generation and the number of synthetic steps required. By combining C-H functionalisation and photoredox catalysis, established synthetic methodology could be applied and incorporated into drug discovery, as part of structure-activity relationship (SAR) exploration and late-stage functionalisation.
Proposed solution and methodology
The successful design and synthesis of a variety of photoactive catalysts forms the basis of this project. The type of catalyst we endeavour to synthesise consists of a core structure functionalised with a variety of organic ligands. By careful design, we aim to investigate the effect of different ligands on the photocatalytic performance of the catalyst, taking into consideration the effects on selectivity, yield, catalytic recycling, and efficiency of the reactions conducted. After the demonstration of the catalytic performance of the photocatalysts and insight is gained into the chemical reactivity and applicability of the catalysts, the next aim of the project involves the development of novel methodology exploiting the catalysts to their full potential. The successful completion of these aims will firstly advance existing reactions that have limitations inherent with the specific catalysts used previously, and secondly, will provide access to currently unknown or inaccessible reaction routes, allowing simple organic substrates to be converted into complex structures, under mild and efficient reaction conditions.
Planned Impact
This CDT will deliver impact aligned to the following agendas:
People
A2P will provide over 60 PhD graduates with the skill sets required to deliver innovative sustainable products and processes into the UK chemicals manufacturing industry. A2P will inspire and develop leaders who will:
- understand the needs of industrial end-users;
- embed sustainability across a range of sectors; and
- catalyse the transition to a more productive and resilient UK economy.
Economy
A2P will promote a step change towards a circular economy that embraces resilience and efficiency in terms of atoms and energy. The benefits of adopting more sustainable design principles and smarter production are clear. For example, the global production of active pharmaceutical ingredients (APIs) has been estimated at 65,000-100,000 tonnes per annum. The scale of associated waste is > 10 million tonnes per annum with a disposal cost of more than £15 billion. Consequently, even a modest efficiency increase by applying new, more sustainable chemical processes would deliver substantial economic savings and environmental wins. A2P will seek and deliver systematic gains across all sectors of the chemicals manufacturing industry. Our goals of providing cross-scale training in chemical sciences with economic and life- cycle awareness will drive uptake of sustainable best practice in UK industry, leading to improved economic competitiveness.
Knowledge
This CDT will deliver significant new knowledge in the development of more sustainable processes and products. It will integrate the philosophy of sustainability with catalysis, synthetic methodology, process engineering, and scale-up. Critical concepts such as energy/resource efficiency, life cycle analysis, recycling, and sustainability metrics will become seamlessly joined to what is considered a 'normal' approach to new molecular products. This knowledge and experience will be shared through publications, conferences and other engagement activities. A2P partners will provide efficient routes to market ensuring the efficient translation and transferal of new technologies is realised, ensuring impact is achieved.
Society
The chemistry-using industries manufacture a rich portfolio of products that are critical in maintaining a high quality of life in the UK. A2P will provide highly trained people and new knowledge to develop smarter, better products, whilst increasing the efficiency and sustainability of chemicals manufacture.
To amplify the impacts of our CDT, effective public engagement and technology transfer will become crucially important. As a general comment, 'sustainability' styled research is often regarded in a positive light by society, however, the science that underpins its effective implementation is often poorly appreciated. The University of Nottingham has developed an effective communication portfolio (with dedicated outreach staff) to tackle this issue. In addition to more traditional routes of scientific communication and dissemination, A2P will develop a portfolio of engagement and outreach activities including blogs, webpages, public outreach events, and contribution of material to our award-winning YouTube channel, www.periodicvideos.com.
A2P will build on our successful Sustainable Chemicals and Processes Industry Forum (SCIF), which will provide entry to networks with a wide range of chemical science end-users (spanning multinationals through to speciality SMEs), policy makers and regulators. We will share new scientific developments and best practice with leaders in these areas, to help realise the full impact of our CDT. Annual showcase events will provide a forum where knowledge may be disseminated to partners, we will broaden these events to include participants from thematically linked CDTs from across the UK, we will build on our track record of delivering hi-impact inter-CDT events with complementary centres hosted by the Universities of Bath and Bristol.
People
A2P will provide over 60 PhD graduates with the skill sets required to deliver innovative sustainable products and processes into the UK chemicals manufacturing industry. A2P will inspire and develop leaders who will:
- understand the needs of industrial end-users;
- embed sustainability across a range of sectors; and
- catalyse the transition to a more productive and resilient UK economy.
Economy
A2P will promote a step change towards a circular economy that embraces resilience and efficiency in terms of atoms and energy. The benefits of adopting more sustainable design principles and smarter production are clear. For example, the global production of active pharmaceutical ingredients (APIs) has been estimated at 65,000-100,000 tonnes per annum. The scale of associated waste is > 10 million tonnes per annum with a disposal cost of more than £15 billion. Consequently, even a modest efficiency increase by applying new, more sustainable chemical processes would deliver substantial economic savings and environmental wins. A2P will seek and deliver systematic gains across all sectors of the chemicals manufacturing industry. Our goals of providing cross-scale training in chemical sciences with economic and life- cycle awareness will drive uptake of sustainable best practice in UK industry, leading to improved economic competitiveness.
Knowledge
This CDT will deliver significant new knowledge in the development of more sustainable processes and products. It will integrate the philosophy of sustainability with catalysis, synthetic methodology, process engineering, and scale-up. Critical concepts such as energy/resource efficiency, life cycle analysis, recycling, and sustainability metrics will become seamlessly joined to what is considered a 'normal' approach to new molecular products. This knowledge and experience will be shared through publications, conferences and other engagement activities. A2P partners will provide efficient routes to market ensuring the efficient translation and transferal of new technologies is realised, ensuring impact is achieved.
Society
The chemistry-using industries manufacture a rich portfolio of products that are critical in maintaining a high quality of life in the UK. A2P will provide highly trained people and new knowledge to develop smarter, better products, whilst increasing the efficiency and sustainability of chemicals manufacture.
To amplify the impacts of our CDT, effective public engagement and technology transfer will become crucially important. As a general comment, 'sustainability' styled research is often regarded in a positive light by society, however, the science that underpins its effective implementation is often poorly appreciated. The University of Nottingham has developed an effective communication portfolio (with dedicated outreach staff) to tackle this issue. In addition to more traditional routes of scientific communication and dissemination, A2P will develop a portfolio of engagement and outreach activities including blogs, webpages, public outreach events, and contribution of material to our award-winning YouTube channel, www.periodicvideos.com.
A2P will build on our successful Sustainable Chemicals and Processes Industry Forum (SCIF), which will provide entry to networks with a wide range of chemical science end-users (spanning multinationals through to speciality SMEs), policy makers and regulators. We will share new scientific developments and best practice with leaders in these areas, to help realise the full impact of our CDT. Annual showcase events will provide a forum where knowledge may be disseminated to partners, we will broaden these events to include participants from thematically linked CDTs from across the UK, we will build on our track record of delivering hi-impact inter-CDT events with complementary centres hosted by the Universities of Bath and Bristol.
