Supermolecular Liquid Crystals - Liquid Crystalline Functional Assemblies and Their Supramolecular Structures - page 32

dielectric properties, and the presence of the smectic C phase indicates that
with the introduction of chirality the material would also be ferroelectric and
pyroelectric. The mesophase sequence of g -12.8 Cryst 1 4.7 Cryst 2 39.0 SmC
74.2 SmA 102.9 ◦ C Iso Liq, demonstrates that the dendritic structure of the su-
permolecule is constrained to being rod-like, see Fig. 36, and that the rod-like
conformers tilt over at the smectic A to smectic C phase transition, as shown
in Fig. 37. Thus, the structures of both the smectic A and the smectic C phases
have alternating organic and inorganic and layers. As the inorganic and organic
layers have differing refractive indices, the mesophase structures are essentially
nano-structured birefringent slabs.
The effect of the length of the spacer chain on the liquid-crystalline prop-
erties of the octamers of octasilsesquioxane, of general structure 38 ,was
Fig. 36 Minimized structure of the octamer, 37 , showing that the dendrimer is cylindrical
in shape
Fig. 37 The structures and phase transition for the smectic A and smectic C phases of
multipede 37 where the spheres represent the terminal cyano moieties