Failures of fractional crystallization: ordered co‐crystals of isomers and near isomers

Failures of fractional crystallization: ordered co‐crystals of isomers and near isomers
Authored by:
Steven P. Kelley
László Fábián
Carolyn Pratt Brock

A list of 270 structures of ordered co‐crystals of isomers, near isomers and molecules that are almost the same has been compiled. Searches for structures containing isomers could be automated by the use of IUPAC International Chemical Identifier (InChI™) strings but searches for co‐crystals of very similar molecules were more labor intensive. Compounds in which the heteromolecular AB interactions are clearly better than the average of the homomolecular AA and BB interactions were excluded. The two largest structural classes found include co‐crystals of configurational diastereomers and of quasienantiomers (or quasiracemates). These two groups overlap. There are 114 co‐crystals of diastereomers and the same number of quasiracemates, with 71 structures being counted in both groups; together the groups account for 157 structures or 58% of the total. The large number of quasiracemates is strong evidence for inversion symmetry being very favorable for crystal packing. Co‐crystallization of two diastereomers is especially likely if a 1,1 switch of a methyl group and an H atom, or of an inversion of a [2.2.1] or [2.2.2] cage, in one of the diastereomers would make the two molecules enantiomers.

Information
Content Type Non OER
DOI https://doi.org/10.1107/S0108768110048135
Content Link https://onlinelibrary.wiley.com/doi/full/10.1107/S0108768110048135
Content Status publish
Number of Comments No Comments
Date Published
Content Tags Audience, Content type, English, Graduate, InChI Application, Publication, Researcher, Search