Liquid Crystal-Induced Circular Dichroism LCICD

6 Liquid Crystal-Induced Circular Dichroism (LCICD) 

Recently, Sato and Hatano 67 69) found a new type of chiral lyotropic mesophase composed of Tween 80, sorbitan mono-9-octadecenoate poly(oxy-l,2-ethanediyl), and water, and discussed the ICD of achiral solute molecules intercalated into the lyotropic mesophase. As the concentration of Tween 80 is increased, three distinct phases are obtained micelle, neat phase, and reversed micelle, in that order. In the region of the volume ratio of Tween 80/(Tween 80 + water) of 0.40 to 0.63 under crossed Nicol-prisms, a focal conic texture was observed. This result indicates that the 

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Liquid crystal induced circular dichroism (LCICD)(46)... 

The u.v. and c.d. spectra of (364 R = Me, Et, Pr, Bu , or PhCH2) in EtOH and in iso-octane have been reported.The chiroptical properties of the oxaziridine chromophore were generally characterized by a positive pattern at 190—350 nm. The notable exception to this was a clear negative Cotton effect for (364 R = Pr ). The seemingly anomalous behaviour of this compound was interpreted in terms of the possible existence of solvation equilibria and conformational rotamers about the N—CHMe2 bond. The relatively new technique of Liquid-Crystal-Induced Circular Dichroism (LCICD) has been used in the... 

Liquid crystal induced circular dichroism (LCICD) examines the differential absorption of circularly polarized radiation by an achiral solute oriented in a cholesteric liquid crystal. The circular dichroism results from an induced Cotton effect in the achiral solute due to the macroscopic chirality of its ordering in the helical solvent matrix. The effect has been shown theoretically to arise... 

We arrive at this conclusion from the lack of more than a slight atropisomeric excess (ca. 0.1% in all but one anomalous experiment) after equilibration of racemic BN in the cholesteric phases at several temperatures (TablelV). The lack of change in the ratio of atropisomers in the cholesteric phases is consistent with our observation that liquid-crystal induced circular dichroism spectra (67) of ISN in cholesteric mixture D are due to a macroscopic property of the solvent the LCICD spectra disappear when mixture D is heated to an isotropic temperature. 

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