Sohncke space group

In literature, SOHNCKE space-group types are often termed chiral space groups , which is not correct. Most chiral molecular compounds do not crystallize in a chiral (enantiomorphic) space group. For details see [86]. 

Do not call an achiral Sohncke space group (or space-group type) a chiral space group . Most chiral molecules do not crystallize in a chiral space group (p. 83). 

Using a simple but informative scheme (Figure 9), Bishop and Scudder outlined four possible outcomes of allowing a 1 1 solution of a racemic mixture to crystallize. Scenario iv results in a mechanical mixture of enan-tiomorphous racemic crystals in which the enantiomers are not related to each other by crystallographic symmetry. Therefore, even though each crystal contains an equal mixture of enantiomers (i.e., dissolution of one crystal does not produce an optically active solution), the molecules must necessarily pack in accordance with one of the 65 Sohncke space groups. Bishop and Scudder called the mechanical mixture of enantiomorphous racemic crystals a false conglomerate, but in a subsequent article, they pointed out that the term kryptoracemate (i.e., hidden racemate. 

Optical Networks —these networks are by their very nature chiral and then crystallize in Sohncke space groups. They are analogous to homochiral compounds. This type of supramolecular isomerism lies at the heart of spontaneous resolution of chiral solids. 

About 75-80% of known compounds crystallize in centrosymmetric space groups. About 80% of the non-centrosymmetric organic structures occur in space groups without an improper rotation axis n (the Sohncke groups). 

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