Pedersen, Charles John (1904-1989), an American chemist, shared the 1987 Nobel Prize for chemistry with Donald J. Cram of the United States and Jean-Marie Lehn of France. Pedersen was awarded the prize for developing a group of organic compounds called macrocyclic polyethers or crown ethers. The molecules in these substances typically consist of carbon, hydrogen, and oxygen atoms arranged in a "crown" shape, or ring. By changing the structure of the crown, Pedersen could trap a variety of metal ions (electrically charged atoms or groups of atoms) in the center of the crown.