Molecular chirality wins this year’s Nobel Prize in Chemistry

On Oct. 7, The Royal Swedish Academy of Sciences awarded the 2026 Nobel Prize in Chemistry to Henri B. Kagan (Universite Paris-Saclay, France) and Kenso Soai (Tokyo University of Science, Japan) “for the discovery of non-linear effects and autocatalysis in asymmetric organic synthesis.”

Ryan Braga, a graduate student working in the Toscano Research Group, shared his insights on Kagan and Soai’s discoveries in an email to The News-Letter.

“Essentially, they uncovered how to amplify reactions to favor a “one-handed” version of a molecule,” he wrote.

Certain molecules have mirror-image forms called enantiomers. These molecules have the same connectivity but differ in 3D arrangement, similar to how your hands have the same number of fingers but cannot directly overlap. Although the appearance of these enantiomers may superficially appear similar, what sound like miniscule differences in configurations can produce catastrophic consequences.

Kagan’s work found that mixing slightly uneven proportions of different (mirror image) catalysts could yield drastically different proportions of the two final products. Enantiomeric excess measures the difference between the percentages of the two enantiomers in a mixture. When a reaction’s product has a different enantiomeric excess ratio compared to a reaction’s catalyst mixture’s enantiomeric excess, it is described as nonlinear. Kagan’s discoveries allowed researchers to take advantage of that nonlinear relationship to produce a high yield on one enantiomer over the other.

On the other hand, Soai discovered a reaction whose product acts as its catalyst, a substance that speeds up a chemical reaction, for its own synthesis; this process is called asymmetric autocatalysis.

“[This process] practically allows a very small difference in the initial excess of one enantiomer of the product to discriminately form more of that enantiomer which leads to nearly all of the molecules becoming one version.” Braga described.

He noted that these important discoveries are necessary in various fields, including to support origin-of-life research such as Charles Frank’s 1953 model for homochirality; Kagan and Soai’s work helps describe why life operates with molecules of one specific enantiomer, such as how all amino acids are L-amino acid proteins except achiral glycine. This involved furthering our understanding of self-reinforcing chiral systems significantly.

“It was extremely interesting work and was foundational to much of the research today which continues to investigate this question about how nature “selected” one enantiomer preferentially,” he wrote.

Aside from their theoretical implications, what are the practical applications these discoveries brought? Braga cited the fact that we routinely design catalysts to yield very pure “single-handed” products, especially in areas like pharmaceuticals. In the late 1950s and early 1960s, thalidomide was prescribed to pregnant women for anti-nausea properties. Over time, it became unmistakable that thalidomide had caused severe birth defects in thousands of children.

“[It] was a potent teratogenic in one enantiomeric form[,] and because the body interconverts the enantiomers[,] it caused birth defects,” he explained.

Thus, this historical anecdote emphasizes the cruciality in producing the correct mirror image.

As a BS/MS chemistry student, Braga’s work in the Toscano Research Group focuses on understanding reactive sulfur species and designing pro-drugs, a pharmacologically inactive or low-activity medication that can become active under specific conditions.

“As an organic chemist, designing [syntheses] around chirality is an important detail and especially in the field [of] drug science[,] chirality cannot be overlooked... In all, this prize has important ramifications for the field of organic synthesis and has shone a light on the origin of life research,” Braga noted.

Soai hopes that his award will inspire future research in chiral molecules.

“Our prize this year should make people recognise the importance of the chirality of molecules so I am especially glad about that. For the next generation, the study of chirality should develop even more and more,” said Soai in a statement cited by the Royal Society of Chemistry.

Together, Kagan and Soai will share the 12 million Swedish kronor prize equally, which is around 1,210,000 U.S. dollars.