With his discovery of the concept of "frustrated Lewis pairs," University of Toronto researcher Doug Stephan unearthed a way to potentially transform industries ranging from food production to drug development by eliminating the need for toxic or expensive metal catalysts.
That was two decades ago. Now Stephan, a University Professor in the department of chemistry in the Faculty of Arts & Science, is being honoured for his seminal work with the Davy Medal, one of the U.K. Royal Society's most prestigious awards.
"For the past 100 years, chemists relied primarily on using rare, precious metals such as rhodium, platinum or palladium to carry out catalysis to convert organic compounds into products and materials we use," says Stephan, noting the metal-dependent chemical process is also crucial for the refinement of crude oil and the creation of plastics.
"As recently as 25 years ago, we were teaching undergraduates that if you want to do a transformation of some small molecule into something useful, you had better use a metal."
First awarded in 1877, the Davy Medal is awarded annually by the Royal Society , the U.K.'s national academy of sciences, to an outstanding researcher in the field of chemistry. The medal is named after Humphry Davy, the chemist who invented the Davy lamp, a safety lamp that enabled coal miners to work more safely in dark, hazardous tunnels.
"Certainly, I was surprised," says Stephan of winning the award. "Obviously, I knew I'd been nominated, but you never know. I feel incredibly lucky to be recognized in this way and to join such distinguished past recipients."
What exactly are frustrated Lewis pairs (FLPs)? They are a groundbreaking alternative to current approaches to catalysis - the process of speeding up a chemical reaction by adding a substance called a catalyst that is not consumed or changed by the reaction. Traditionally, metals have been used to catalyze these transformations, often leaving behind toxic residues. FLPs instead use a type of acid-base combination to drive reactions without releasing harmful byproducts.
"You can use things that are much more common, like phosphorus, boron or nitrogen," says Stephan. "You can take small molecules containing these elements which are more easily available and use those to carry out these transformations."
Though FLPs offer a cleaner, more attractive alternative, they are not used commercially yet. The use of metals is still widespread, particularly metal-based hydrogenation - adding H2 to molecules. One common example of this can be found with peanut butter.
"If you've seen natural peanut butter, it has that oil on top," says Stephan. "That's in its unsaturated state, but if you saturate it by adding hydrogen, you get the brands we love like Skippy. Adding hydrogen congeals it into this semi-solid state most people prefer."
But the application of FLPs could extend well beyond our favourite morning spread - their potential to replace metals within commercial applications is enormous.
"It's estimated that over 90 per cent of all chemical products rely on a production process involving at least one catalytic fabrication step, with a substantial portion of those depending directly on a hydrogenation reaction," says Stephan.
"In the pharmaceutical sector, roughly 40 per cent of all drug syntheses involve at least one hydrogenation. All of these depend on metals at present."
Reducing the use of metals could make for lower production costs and a cleaner environment.
"In the case of drugs, 70 per cent of the cost of production is spent on purifying the products to remove traces of toxic metals used in the production processes," says Stephan. "If you used an FLP instead, the cost of production would be reduced both in terms of both costs and energy."
Stephan's discovery of FLPs originally occurred in 2006, but potential commercial applications have only begun taking shape in recent years.
"These things take a long time," says Stephan, noting that decades can pass between an initial discovery and practical applications, citing the personal computer as an example.
"We first started using personal computers in the early 1980s," he says. "But the concept of the computer was formulated in the 1940s. There were obviously developments along the way, but it was a 40-year gap from initial concept to commercial product."
Stephan believes we won't have to wait another 20 years until FLPs make a significant impact. He's already seeing major companies show serious interest in applying FLPs to their chemical processes.
"Dow Chemical in Michigan are developing FLP reagents for the catalytic production of a variety of silicon compounds and materials, widely used for waterproof sealants, lubricants and medical tubing," he says.
Already heartened by such developments, winning the Davy Medal is especially satisfying for Stephan because of his long-standing connection with the Royal Society.
"I was elected a Fellow 13 years ago, and it's a really outstanding organization," he says. "I've served on their editorial board for their journal and on their selection committee for new Fellows. So, it means all the more that they're recognizing our work."
And while he is delighted to receive the accolade, he derives more satisfaction from being nominated by his peers.
"I don't think you do science for the awards," he says, though he's received several over his career including a Guggenheim Fellowship in 2020, the 2021 Killam Prize for Science, and the 2022 American Chemical Society Cotton Award. He was named a Fellow of the Royal Society of Canada in 2005, a Fellow of the Royal Society in 2013 and an Officer of the Order of Canada in 2024.
"What's most gratifying is to have your peers nominate you. Ultimately what a scientist has is his or her reputation and the impact of their work. And if people think that it's valuable and worthy of consideration, that's enough, that's a win."
That's why he calls the Davy Medal "the icing on the cake."
"Now that the concept is out there in the chemical community, people are taking it and going in completely different directions that we didn't even think about," he says. "There's been some spectacular work stemming from our initial discovery, and that's extremely gratifying."
