Alexander Kuhn, the chemist who breaks the rules

Alexander Kuhn in his laboratory at the ISM in Bordeaux in April 2024.
Alexander Kuhn in his laboratory at the ISM in Bordeaux in April 2024.
The winner of the 2023 CNRS Silver Medal, Alexander Kuhn has marked the scientific community with his research in electrochemistry, which is of interest in fields ranging from pharmaceuticals to robotics. An interview with this incredibly creative researcher who is passionate about experimentation.

A raft of prizes adorn the wall and credenza behind his desk, so many trophies bearing witness to an exemplary career. Alexander Kuhn is the archetype of scientists as we imagine them - experts in their field with prolific creativity. "He makes connections between things very quickly. He’s one of the most creative chemists I know," describes Laurent Bouffier, his colleague at the ISM 1 in Bordeaux (southwestern France). A trait that explains his many successes. "There are a number of ways to conduct research. In 90% of cases, you are proceeding with implementation, in other words marginally improving what has already been done before. But his work does not follow that pattern. The ideas he develops are original, and he likes breaking the rules."

During his thirty-year career, Kuhn has left his mark on the scientific community with his discoveries, including chiral molecules as well as the relatively unfamiliar technique of bipolar electrochemistry.

Between chemistry, physics, and biology

Batteries, photovoltaic cells, fuel cells...all of these industrial products are based on principles from electrochemistry, a booming field that explores the relations between chemistry and electricity, and that can also produce "green" hydrogen or synthetic molecules for the pharmaceutical industry. Kuhn is currently concentrating his research on the latter.

In a first advance, his work took a fresh view of how to produce medicine, one in which chiral molecules serve as active pharmaceutical ingredients. Their synthesis normally leads to a half-half mix of the two enantiomers, with antagonistic effects. "Only one of the two enantiomers has a therapeutic effect. The other does not, and can even be toxic or lethal," Kuhn explains.

The process proposed by the researcher and his team can selectively synthesise the right enantiomer, without having to sort through them. This is a major departure from the traditional processes used by pharmaceutical laboratories, which have to sort them when producing combinations. "Until recently we were studying model molecules, but over the last three years we have been working on real ones of pharmacological interest such as adrenaline, which also works well," Kuhn rejoyces.  

A second advance is the principle of bipolar electrochemistry, which illustrates the workaround that Kuhn has successfully performed in his work. While traditional electrochemical reactions require electrodes directly connected to a source of electricity, he had the idea of placing a conducting object between the electrodes. The electric field generated around the object is what that triggers electrochemical reactions. This represents a genuine conceptual change that paves the way for otherwise inconceivable applications, such as deforming soft matter like plastics remotely, using an electrical signal - rather like the movement of our muscles when they respond to the nerve signal produced by our brain. The team recently developed a miniature system based on a biocompatible conductive polymer that uses sugar, oxygen, and an electromechanical reaction to change its shape autonomously, and to periodically produce a movement similar to that of a beating heart.

An artist in experimentation

While his research has drawn strong interest from industrial actors, the scientist does not reason in terms of societal impact, results, or productivity: "I like playing with ideas and concepts. What I’m interested in is creating. If you think too much about the future application, that limits the imagination. Sometimes my research does not lead anywhere. I am very selfish, I became a researcher because my only motivation is to have fun," Kuhn says in jest. "I can’t stand projects where you have to precisely predict what you are going to obtain. In the beginning, lasers were a laboratory curiosity. Nobody said they would one day be used for eye surgery, or to read CDs, or to cut a sheet of metal. Most discoveries do not come from a top-down process, but rather the opposite." 

Kuhn willingly acknowledges that his discoveries are often inspired by everyday life, or by the nature that surrounds us. It was while walking in his garden that he had the idea of developing a propulsion strategy based on the natural photosynthesis of plants. He did so by applying microsurgery to the veins of a tree leaf in order to modify its structure. When immersed in water and coming into contact with light, the leaf began to move thanks to the targeted release of oxygen during photosynthesis. Unlike most of the systems used to date, no chemical fuel is needed to activate the leaf. If you ask why do such a thing, Kuhn’s answer can be disconcerting: "It’s art for art’s sake."

The scientist has been conducting experiments since he was a child. "I always knew I wanted to be a chemist," he says. At the age of 15, he set up a laboratory in the basement of his family’s house near Munich, Germany, where he conducted experiments on polymer materials. "I was fully equipped. I spent all my pocket money on it. I had my round flasks and distillation columns, and I asked companies to donate solvents. I told them I was a young scientist, and sent them letters asking for funding. Much to my surprise, it worked." And for good reason, for at the age of 16 he won first prize in the Jugend Forscht German national competition for his research on conductive polymers.

The electrochemist’s ideal 

After completing chemistry studies in Munich, Kuhn came to France in the early 1990s to pursue his PhD at the Paul Pascal Research Centre (CRPP) 2 , also in Bordeaux. There he "grew" metal via an electrochemical reaction, like branches on a tree: "The idea was to understand the logic of how tree structures grow. We wanted to know whether we could identify explanatory patterns for these phenomena," he explains.

He then went to the United States for a postdoctoral fellowship at the California Institute of Technology (Caltech), which he described as "the best time in career": "I had the dream life of a scientist. I enjoyed total intellectual and financial liberty. I didn’t have to look for funding, no administrative tasks, no heavy responsibilities. Today my obligations are not quite the same." Twenty years on, Kuhn’s everyday assignments are divided between teaching, conducting research, and requesting funding for his work at the ISM - a real constraint for this creative mind for whom research involves anything but planning, even though scientific work is increasingly following this trend.

This professor at the ENSMAC materials, agrifood and chemistry school must still endeavour to promote his research. "One of our challenges in terms of democratising our processes in the future is scaling-up. Some of the ideas we concretely produced work at the laboratory level, but not for industrial production. There are technological obstacles that must be overcome, such as optimising the performance of electrodes and their lifespan, as well as improving the transportation of materials in solution. I believe that electrochemistry is the science of the twenty-first century. We cannot do without it if we want to find a solution to our environmental and technological problems."

Sometimes Kuhn also dreams of new processes. One of his hopes, like every self-respecting twenty-first-century (electro)chemist, is "to transform carbon dioxide (CO2) into something useful. If we succeed in developing an electrochemical process that can extract this gas from the atmosphere and then reuse it, we’ll kill two birds with one stone in terms of global warming". Believing in his dreams in order to make them come true seems to be second nature with Kuhn. And one that’s due to last. ?