Case Study on the Interpretation of Crystal Structures Inducing Preferential Enrichment Based on the Graph Set Analysis of Hydrogen Bond Motifs

The hydrogen bond motifs in the racemic crystals of the first-generation of chiral organic compounds, which showed a good to excellent preferential enrichment (PE) phenomenon, were rationalized by graph set analysis in terms of the selective dissolution of the excess one enantiomer from the transformed disordered crystals. By comparing these motifs with those of several analogous compounds incapable of showing PE, the graph sets necessary to induce PE with respect to the first-generation compounds were unveiled. On the basis of this graph set study, compounds with a new type of crystal structure (β1-form) and graph set which can induce PE have been revealed.