The Nobel Prize in Chemistry 1964 was awarded to Dorothy Crowfoot Hodgkin "for her determinations by X-ray techniques of the structures of important biochemical substances".
 

In 1948 Mrs. Hodgkin began her attempts to determine the structure of vitamin B12, which had been isolated in the same year. This vitamin can be synthetized by certain bacteria and fungi, of which some play an active part in the digestive processes of animals. In 1956, after eight years' work, Mrs. Hodgkin and her collaborators had clarified the B12 structure. Never before had it been possible to determine the exact structure of so large a molecule, and the result has been seen as a triumph for X-ray crystallographic techniques.

Professor Hodgkin have solved a large number of structural problems, the majority of great importance in biochemistry and medicine. The first is the determination of the structure of penicillin. The second, the determination of the structure of vitamin B12, has been considered the crowning triumph of X-ray crystallographic analysis, both in respect of the chemical and biological importance of the results and the vast complexity of the structure.