Nobel Prize in Chemistry 2026: Only a reflection counts

When you look in the mirror, pull your right ear. Your mirror self won't be able to help but follow you. Only instead of the right it pulls on the left ear. In a sense, you are in two worlds, they are basically the same - just in reverse. And one world can never become the other.

The same goes for chemistry in the real world we all live in. The chemical building blocks of life were all built in one way. These molecules could also exist mirrored. But they don't. Research is puzzling as to why this is the case.

Now this year's Nobel Prize in Chemistry honors two researchers who have found a partial answer. The first breakthrough was in 1986 by the French researcher Henri Kagan from the University of Paris-Sud. In 1995, the Japanese Kenso Soai from the University of Tokyo built on his findings. Together they share the prize money of 12 million Swedish crowns, around one million euros.

It is the third Nobel Prize this week that has been awarded to truly fundamental research discoveries and underlines the relevance of basic research. But it is also the third Nobel Prize in the natural sciences this week that goes solely to male researchers. Not a single female researcher received an award this year.

The phenomenon in question is called chirality and is derived from the Greek word for hand. This can be used to describe molecules that are the same but not congruent - like a right and a left hand, they cannot be placed on top of each other. Whether a molecule is right- or left-handed is particularly relevant for organic chemistry, i.e. the part of chemistry surrounding carbon atoms, from which all life is made up.

In principle, a chemical reaction can produce both a right-handed and a left-handed variant of the end product. This was also reflected in the results of the researchers' laboratory tests. They found both variants equally in their final product. However, living organisms prefer to produce one species.

The different variants can have very different effects in practice. This became particularly shockingly apparent with the thalidomide scandal that was uncovered in the early 1960s.

The drug, which was supposed to calm, damaged fetuses in the uterus of pregnant people because the mirror-inverted version of a molecule had a completely different effect in the body. But things are more complicated with Contergan: the body can convert the two variants of the molecules into one another. That's why it wouldn't have helped to just use the right one of the molecules.

This is precisely why chemists and pharmacists are very interested in ensuring that only one form is created. Fascinatingly, the body does this on its own. When reactions occur in living organisms, they repeatedly produce only one mirror variant. And how did nature manage to keep reproducing a variant within itself?

The first assumptions about this were made in 1953 by Charles Frank, a theoretical physicist from Great Britain who died in 1998. He predicted that one variant of the final product could serve as a catalyst for the reaction, producing more of his own variant.

Kagan and Soai succeeded in designing exactly such reactions and proving this mechanism. They showed how homochirality, i.e. a mirror variant, can arise in nature without external intervention. Nevertheless, this is only one building block in explaining why the chemistry of life is almost one-handed. Researchers are still investigating this origin.

For Kagan, the Nobel Prize is probably another special honor. A Nobel Prize went to the department back in 2001; it was also about how chemical reactions can be designed using an external catalyst in such a way that a product is increasingly created. Back then, Kagan came away empty-handed, even though he also did pioneering work. As a result, according to reports in the specialist magazine Nature, even the French science minister wrote a letter of protest to the Nobel Prize Committee, but Kagan distanced himself from it. Now the 95-year-old Kagan is receiving the honor for his life's work.

With their fundamentals and reaction pathways, Kagan and Soai shape chemistry and its industry. In addition to active ingredient design in the pharmaceutical industry, the mechanisms also help to create individual mirror variants in the production of materials or even perfume. The mirror images not only act differently as medications, they also smell different. Maybe think about that next time you smell a lemon or orange. Their scent is the reflection of the same molecule.