Selective small molecule activation towards sustainable chemical synthesis

The development of new sustainable processes is a crucial goal of modern chemistry. Most large-scale reactions currently employed by the chemical industry consume non-renewable resources and require catalysts based on metals which are often scarce, expensive and toxic. This is especially true for plastics made from hydrocarbon-based polymers such as polyethylene. These are produced from petrochemicals and so their production requires the continued extraction of the earth's limited supply of fossil fuels and drives climate change. These plastics are also non-biodegradable, resulting in well documented environmental issues caused by their accumulation in the ocean and other natural habitats.
As such the production of biodegradable polymers from renewable resources is of paramount importance. One promising solution is the use of molecules such as lactones and lactide, which are known as cyclic esters and are produced by fermenting renewable biomass such as corn and sugar beets. These molecules are cyclic, but their ring-shaped structures can be activated by a catalyst containing a charged metal ion. This enables a reactive carbon-oxygen bond to be broken, opening up the ring to form a short linear chain, which can then be linked with others to form a long polymer chain by forming new carbon-oxygen bonds between them. The metal catalyst speeds up the reaction and is regenerated at the end of the cycle, potentially enabling it to be recycled.
The development of new catalysts that enable the controlled synthesis of polymers at low temperatures is key. The use of metal-carbon based catalysts is a well-established method for activating small molecules such as lactones and lactide and enabling their transformation into useful products. With sustainability in mind, it is beneficial for any new catalysts to contain metals which are abundant, cheap and non-toxic. These sustainability criteria are satisfied by the so-called alkaline earth metals that occupy the second column of the periodic table (group 2), making them attractive candidates for use as sustainable catalysts. In particular, the heavy group 2 elements strontium and barium hold untapped potential as catalysts and are worthy of further investigation. Other potential candidates are the elements samarium, europium and ytterbium - like strontium and barium these heavy elements are large in size, while also being abundant and non-toxic relative to other heavy metals.
This project falls within the EPSRC Physical Sciences research area and will take place in the O'Hare group. Its initial aims will be to develop novel catalysts containing strontium and barium, at a later stage complexes containing samarium, europium and ytterbium will also be investigated. Computational methods will be brought into the project via a collaboration with the McGrady group. The objective will be to develop structure-function relationships for these catalysts. The reactivity of these complexes with lactones and lactide will be investigated to determine which metal most effectively catalyses the production of biodegradable polymers.

The primary impact of the OxICFM CDT will be the highly-trained world-class scientists that it delivers. This impact will encompass both the short term (during their doctoral studies), the medium term (subsequent employment) and ultimately the longer timescale defined by their future careers and consequent impact on science, engineering and policy in the UK.

The impact of OxICFM students during their doctoral studies will be measured by the culture change in graduate training that the Centre brings about - in working at the interface between inorganic synthesis and manufacturing, and fostering cross-sector industry/academia working practices. By embedding not only from larger companies, but also SMEs, we have developed a training regime that has broader relevance across the sector, and the potential for building bridges by fostering new collaborations spanning enormous diversity in scientific focus and scale. Moreover, at a broader level, OxICFM offers to play a unique role as a major focus (and advocate) for manufacturing engagement with academic inorganic synthetic science in the UK.

From a scientific perspective, OxICFM will be uniquely able to offer a broad training programme incorporating innovative and challenging collaborative projects spanning all aspects of fundamental and applied inorganic synthesis, both molecular and materials based (40+ faculty). These will address key challenges in areas such as energy provision/storage, catalysis, and resource provision/renewal necessary to enhance the capability and durability of UK plc in the medium term. To give some idea of perspective, the output from previous CDTs in Oxford's MPLS Division include two start-up companies and in excess of 30 patents.

It is not only in the industrial and scientific realms that students will have impact during their timeframe of their doctorate. Part of the training programme will be in public engagement: team-based challenges in resource development/training and outreach exercises/implementation will form part of the annual summer school. These in turn will constitute a key part of the impact derived from the CDT by its engagement with the public - both face-to-face and through electronic/web-based media. As the centre matures, our aspiration is that our students - from diverse backgrounds - will act as ambassadors for the programme and promote even higher levels of inclusion from all parts of society.

For our partners, and businesses both large and small in the manufacturing sector, it will be our students who are considered the ultimate output of the OxICFM CDT. Our programme has been shaped by the need of such companies (frequently expressed in preliminary discussions) to recruit doctoral graduates who can apply themselves to a broad spectrum of multi-disciplinary challenges in manufacturing-related synthesis. OxICFM's cohort-based training programme integrates significant industry-led training components and has been designed to deliver a much broader skill set than standard PhD schemes. The current lack of CDT training at the interface of inorganic chemistry and manufacturing (and the relevance of inorganic molecules/materials to numerous industrial sectors) heightens the need for - and the potential impact of - the OxICFM CDT. Our students will represent a tangible and valuable asset to meet the long-term skills demand for scientists to develop new materials and nanotechnology identified in the UK Government's 2013 Foresight report.

In the longer term, the broad and relevant training delivered by OxICFM, and the uniquely wide perspective of the manufacturing sector it will deliver, will allow our graduates to obtain (and thrive in) positions of significant responsibility in industry and in research facilities/institutes. Ultimately we believe that many will go on to be future research leaders, driving innovation and changing research culture, and thereby making a lasting contribution to the UK economy.