French chemist who, together with Charles J. Pedersen (Pedersen, Charles J.) and Donald J. Cram (Cram, Donald J.), was awarded the Nobel Prize for Chemistry in 1987 for his contribution to the laboratory synthesis of molecules that mimic the vital chemical functions of molecules in living organisms.

Lehn earned a Ph.D. in chemistry from the University of Strasbourg in 1963, and in 1970 he became a professor of chemistry at Louis Pasteur University in Strasbourg. From 1979 he was also a professor at the Collège de France in Paris.

Lehn expanded on Pedersen's achievement in creating crown ethers, a class of two-dimensional, ring-shaped organic compounds that are capable of selectively recognizing and combining with other molecules. In the course of his efforts to synthesize three-dimensional molecules that would possess similar reactive characteristics, Lehn created a molecule that combines with the chemical acetylcholine, which is an important neurotransmitter in the brain. His work raised the possibility of creating totally artificial enzymes (enzyme) that would have characteristics superior to their natural counterparts in the human body.