The 2026 Nobel prize in chemistry has been awarded to Henri Kagan and Kenso Soai for their discovery of how to make molecules form the correct kind of mirror image. This has enabled the molecules to be mass produced with chemical properties that are useful in various applications, such as medicines and agriculture.

Some molecules exist in two forms that are mirror images of each other, which chemists call right- and left-handed. “Like my hands, they are one another’s mirror image, they look alike but they are not identical,” Heiner Linke, chair of the Nobel committee for chemistry, said at a press conference. “Such molecules are called chiral from the Greek word for hand.”

For decades, whenever chemists carried out chemical reactions, they produced two forms of mirrored molecules in equal proportions. But they only wanted to make one of the mirror images when producing molecules that would interact with life, like medicines, because only one would have the desired effect.

“Many active drugs in pharmaceutical applications are chiral: one hand may have the desired therapeutic effect, while the other hand might have no effect, or in the worst case might even be harmful,” said Linke.

In 1986, Henri Kagan at Paris-Saclay University, France, discovered a way to tilt chemical reactions towards generating more of one mirror molecule over the other.

Taking this further, in 1995, Kenso Soai at the Tokyo University of Science, Japan, started designing chemical reactions to produce only one mirror image. In 2003, he achieved this. His “Soai reaction” gets one form of mirror molecule to amplify itself, in a process known as autocatalysis, so it makes up most of the reaction products.

This has enabled the mass production of drugs, from painkillers to antidepressants and drugs that treat Parkinson’s disease. It has also helped to produce pesticides that improve crop yields.

“This is one of the most exciting days in my life,” said Soai, who phoned in to the press conference.