INDUCED CHOLESTERIC PHASES OF CHIRAL AMINOANTHRAQUINONES

The temperature dependence of the HTP of 1,4-bis-(S-1-(1-naphthyl)ethylamino)-9,10-anthraquinone [S-5] or [R-5] and of 1,8-bis-(S-1-(1-naphthyl)ethylamino)-9,10-anthraquinone [S-6] in ZLI 1695 (Merck) is expounded to be a consequence of a shift of an equilibrium between at least two conformers A ⇄ B with an equilibrium constant K < 1, derived from the temperature dependence of a CD couplet. Conditional on this equilibrium, the HTP(T) is a linear function of the amplitude of the couplet. The sign of the CD of the isotropic solution is determined by the conformer A whereas the sign of the HTP is given by B. The helix inversion for [S-5] in ZLI 1132 (Merck) appears to be a result of a slightly increasing concentration of the conformer B. © 1992, Taylor & Francis Group, LLC. All rights reserved.