Unraveling the Centennial Mystery of "Homochirality" French and Japanese Scholars Win Nobel Prize in Chemistry

The Royal Swedish Academy of Sciences announced on the 7th that 96-year-old French scientist Henri B. Kagan and 77-year-old Japanese scientist Kenso Soai jointly won the 2026 Nobel Prize in Chemistry for their discovery of nonlinear effects and autocatalytic reactions in organic asymmetric synthesis. The two solved a century-old problem in the chemical world of how to form only the mirror image form of a single molecule, which is of decisive significance to modern pharmaceutical engineering.

Kagan is currently an honorary professor at the Universite Paris-Saclay in France, and Kenzo Kip is an honorary professor at the Tokyo University of Science in Japan. The two will share the prize of 12 million Swedish kronor (approximately NT$38.1 million).

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A press release on the Nobel official website pointed out that many molecules such as amino acids exist in two forms that are similar in appearance and are mirror images of each other, just like the human left and right hands. This chemical phenomenon of life is called "homochiral" by the scientific community. What is puzzling is that although the molecule has two mirror images, only one of them exists in the protein of human cells, and the other is extremely rare in nature. How this chemical asymmetry arises has always been a mystery in the chemical community.

In the past, when scientists tried to make these molecules in test tubes, they always ended up with a mixture of the two mirror images in equal proportions. The Academy of Sciences compares the problem to building a key: a locksmith will create two variations each time, positive and negative, but only one of them can open the lock. If the wrong key is used, the lock may even be damaged.

Heiner Linke, chairman of the Nobel Prize Committee in Chemistry, said that the combination of Kegan and Kip provides a solution to a chemical mystery that has lasted for more than a century, that is, how homochiral properties arise spontaneously.

In 1986, Kegan discovered a new method of manipulating chemical reactions (nonlinear effects) that allowed him to create one of these mirror ratios, far beyond the limits previously thought possible by science.

Kip He took the next step to turn his dream into reality. In 1995, he presented a key paper and designed the first chemical reaction in history that could achieve isochirality. In 2003, Kip He successfully proposed a reaction (autocatalytic reaction) that would only form a single mirror image, which was called the "Soai reaction" by academic circles. No one has ever done this before, except in nature itself.

96-year-old Kagan’s belated glory

"This is certainly one of the most exciting days of my life," Kip Hop told the committee and reporters on the phone by phone. As for Kagan, this year’s Nobel Prize in Chemistry was a long overdue honor. The 2001 Chemistry Prize was awarded to three scholars who had pioneered research in the field of "asymmetric catalysis." However, Kegan, who is internationally recognized as the "founding father" of this technology, became the legacy, which triggered protests and controversy in the French chemical community.