Chiral Chromonic Phases

There appear to be no reports of small molecule chiral chromonic mesogens, but it is easy to convert the nonchiral N phase into a cholesteric phase by adding a small water-soluble chiral solute such as an amino acid. Lee and Labes carried out an extensive study of the relationship between the pitch of the induced chiral phase and the concentration of various dopants [55]. They found that the twist varies linearly with concentration over large concentration ranges, and the helical twisting power is characteristic of the particular dopant. This approach offers a novel form of assay for small quantities of water-soluble chiral compounds. 

The fingerprint texture of a chirally doped chromonic drug N phase. This sample shows the N -t I phase of a 5% solution of arginine in a 22% sample of DSCG at room temperature. The separation of the striations corresponds to 1/2 the pitch of the helicoidal structure. (x300, crossed polars.)... 

E phases, calamities 12 edge disclinations, chiral nematics 354 Ehrlich magic bullet, chromonics 984 elastic constants 63, 79 ff... 

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