The Nobel Prize in Chemistry 1987 was awarded jointly to Donald J. Cram, Jean-Marie Lehn and Charles J. Pedersen "for their development and use of molecules with structure-specific interactions of high selectivity".
 

Charles Pedersen provided the initial breakthrough by synthesizing a group of chemicals that he called crown ethers on account of their structure – two-dimensional and flexible rings shaped like a royal crown that consist of chains of carbon atoms with oxygen atoms appearing at regular intervals. . Pedersen discovered that introducing more or less atoms into a ring to vary its size affected which metal element the ring could house within its centre.
 

Pedersen's flat crown ethers provided the platform for Jean-Marie Lehn and Douglas Cram to develop increasingly sophisticated compounds that selectively recognised the type of chemicals found in a living cell. Lehn succeeded in creating three-dimensional crown ethers from multiple layers of atoms with interconnected chains, which contained an internal cavity that could completely encapsulate a molecule.
 

Cram designed a series of progressively complex prototype molecules and then successfully synthesized them in the laboratory.