Hodgkin's research on this topic began in 1948 when E.L. Smith of Glaxo Laboratories gave her red crystals of a newly isolated anti-pernicious anaemia factor, named vitamin B12. Hodgkin and a varying group of young crystallographers carried out their analysis by the parallel investigations of four different crystal structures, dry B12, wet B12, the selenocyanide derivative of B12 (Se CN), and a hexacarboxylic acid or the 'red fragment' of B12. The crystal structures of the four B12 derivatives were then the most complicated ones which had been solved in any detail by x-ray analysis.

See MS. Eng. c. 5581/3 for a record of the progress of the vitamin B12 research in Hodgkin's laboratory, July 1954-June 1955. See MS. Eng. c. 5608/23 for a later overview by Hodgkin of the vitamin B12 research.

In the course of the research Hodgkin's group collaborated closely with Smith at Glaxo, J.G. White at Princeton, and A.R. Todd at Cambridge; it was Todd who announced the solution of the structure of vitamin B12 in 1955. In view of the size of the molecule and the extensive calculations involved, the use of early electronic computers at the University of California, Los Angels (K.N. Trueblood), Manchester University and the National Physical Laboratory, Teddington proved extremely important.

Hodgkin's research on vitamin B12 continued into the 1980s with work on the dimethy-benzimidazole-cobamide (DMBC) coenzyme, factor V1a, neovitamin B12, and monocarboxylic acid.

The material, which is substantial, covers the period, 1948-84, although the bulk dates from 1950s and the early 1960s. There is an extensive correspondence including Smith, White, Todd and Trueblood, drafts for reports and publications, notebooks, a large number of research folders, and data.