THE INFLUENCE OF NEW D-SECO-ESTRONE DERIVATIVES ON THE BEHAVIOR OF THE CHOLESTERIC LIQUID CRYSTALS BINARY MIXTURES.

We have studied the influence of the new chiral non-mesogenic seco-estrone derivatives 1-7, synthesized in several synthetic steps starting from estrone, onto the physical characteristics of the binary mixtures of cholesteric liquid crystals. We have examined the phase transitions of the mixture of cholesteryl laurate and cholesteryl enantate with the added chiral non-mesogenic additives 1-7 (45%-45%-10%; Mix.1-Mix.7, respectively). A considerable shift of the I→Ch phase transition temperature, as well as of the temperature of the SmA* phase formation, was observed. X-ray diffraction data enabled the determination of the molecular structures of the compounds 3, 5, 6 and 7, the crystal lattice parameters of the new chiral additives and their molecular length (ℓ) and width (d*), as well as some parameters of the mixtures Mix.1-Mix.6: the thickness of smectic layers and the longitudinal spacing distance in the cholesteric phase (d) and the average distance between the long axes of neighbouring molecules (D). Using molecular-mechanic calculations, on the basis of solved molecular structures, the most probably conformation of the other compounds (1, 2 and 4) used in this work is determined. We have also investigated the influence of these chiral additives onto the pitch of the cholesteric helix of a binary mixture of cholesteric liquid crystals. [ABSTRACT FROM AUTHOR]