How was Charles J. Pedersen awarded the Nobel Prize?

Name: Charles J. Pedersen. 
Country: United States.
Date of Birth: 3 October 1904.
Date of Death: 26 October 1989.
The subject of Study:  Chemical synthesis, Crown ether.
Noble Prize Year: Nobel Prize for Chemistry in 1987 for their research development and use of molecules with structure-specific interactions of high selectivity.