A Royal Society University Research Fellow and Reader in Organic Chemistry, Dr Alex Cresswell works at the interface of sustainable chemistry and pharmaceutical development. Through his research with visible light catalysis, he and his team are developing more efficient, environmentally conscious methods for producing medications. In this interview, Dr Cresswell discusses his research vision and his new role as Associate Director of Sustainable Chemical Technologies.

For those unfamiliar with chemistry, how would you describe your research?

Organic (carbon-based) molecules are the building blocks of life, shaping everything from the food we eat to the medicines that heal us, and the materials that power our technologies. In the field of organic synthesis, we use chemical reactions to produce (‘synthesise’) molecules that are valuable to society, such as pharmaceuticals and agrochemicals. These substances are made in lower volume than commodity chemicals, but are structurally far more complex and therefore much harder to make. For example, drug manufacture often requires the sequencing of multiple energy-intensive reactions, and generates huge quantities of toxic waste (up to 100 kg per kg of drug) which is typically incinerated. Alongside other factors, this is one reason why the pharmaceutical sector has an even higher carbon footprint than the global automotive industry. In my lab, we work with pharmaceutical partners to design inventive new chemistry for more efficient (‘green’) synthesis of drugs, specialising in the use of catalysts powered by visible light to carry out previously impossible transformations.

What do you see as the most significant breakthrough in your field in recent years?

The most transformative advance in organic chemistry over the past decade is probably the invention and exploitation of visible light photoredox catalysis. In this approach, catalysts activated by LED irradiation can tear a single electron out of a molecule (or, conversely, inject an electron into a molecule) and generate spectacularly reactive entities called ‘radicals’. These engage in all manner of peculiar reactivity that is completely alien to ordinary molecules. Some of the chemical reactions that have been achieved with this technology are frankly mind-blowing, and will require us to re-write the textbooks. Most importantly of all, photoredox catalysis is increasingly becoming a standard tool in industry, and has already been used in the tonne-scale manufacture of fine chemicals.

How might this breakthrough accelerate the transition to a more sustainable future?

It’s important to stress that scientific breakthroughs relevant to the more sustainable manufacture of fine chemicals like drugs are just one piece of a much larger puzzle. Almost 30% of the world’s total energy is spent on oil and gas operations and the production of steel and cement, with the chemical industry consuming ~10% of the world’s energy. Of the latter figure, the largest share (2%) comes from just one chemical: ammonia (Haber-Bosch process). So, it’s important to keep drug manufacture in context here. That said, there are economic and societal pillars to sustainability too, and more efficient drug synthesis can translate to cheaper medicines. A big win for humankind would be to make drugs available to those who cannot otherwise afford to pay the prices being charged in Western societies.

What has been your proudest achievement to date?

Our proudest achievement has been inventing a revolutionary new way of synthesising nitrogen-containing chemicals called amines, which are used in the manufacture of almost all small-molecule drugs. The precise transformation we realised was singled out in 2019 by the pharmaceutical industry as a “key unsolved problem for synthetic chemistry” (see Science 2019, 363, eaat0805), so it’s very exciting that we found a reasonably general solution to it! This chemistry is now run on hundreds of grams at several different companies.

What excites you most about your new role as Associate Director of the Institute of Sustainability and Climate Change?

The most exciting thing is working with and mentoring ambitious early career researchers, and helping to pollinate cross-disciplinary collaborations. Or at least, that will be the most exciting thing once I’m a little more acclimatised in the new role. I think the major challenge will be communication across disciplines, and bringing academics with different specialisms together in a synergistic way.

What would you like more people to know about the ISCC and its work?

In terms of the general public, I wouldn’t want anyone to assume that the ISCC and its membership have all the answers to sustainability challenges that society faces. Everybody has a part to play here, and involving the public in the conversation is critical, not least to contextualise and promote the work that our core members are doing. It’s a very broad church indeed, and there is something for everybody, whether it's plastic recycling, modelling carbon flows in petrochemical supply chains, or designing automated reactors that use machine learning to self-optimise new reactions!

What’s one action individuals or communities can take to make a real difference?

Holding our elected representatives to account on climate action, and the need to put long-term investment in green technologies ahead of short-term political convenience. For example, it’s hard to preach the importance of this issue to India and China when our own government reneges on £28BN of green investments and proposes a third runway at Heathrow. My fear is that Net Zero is in danger of becoming a hollow political slogan, and that a bit of ‘greenwashing’ by the public or private sector will be accepted by the public as a surrogate for real action.

Sustainability research often focuses on challenges, but where do you find reasons for optimism?

Obviously, sustainability in our society cannot be reduced to a set of chemical problems, and it's clear that systems thinking and human behavioural science on a macroscopic scale are essential ingredients to make progress. But, in so far that there are very tangible chemistry-related problems in sustainability, I’m optimistic about the community’s rise to meet these challenges. Chemists are very creative people and good at thinking outside the box. Whenever I’m feeling pessimistic about anything, I always just go and talk to my PhD students!