Supermolecular Liquid Crystals - Liquid Crystalline Functional Assemblies and Their Supramolecular Structures - page 10

Fig. 10 Schematic of the molecular packing arrangement in the smectic A and smectic C
phases of a dendron, 14 , based on the 4-alkoxy-4 -cyanbiphenyl moiety
As noted above, increased numbers of mesogenic units attached to a cen-
tral point can be created by introducing a central scaffold upon which to
build the supermolecular structures. Thus cyclic, caged, or hyperbranched
scaffolds can be utilized, as shown in Fig. 1. Such supermolecular materials
can be thought of as dendritic structures when the mesogenic units are all of
the same type. Figure 11 depicts the general structure of a dendrimer where
repeating branched units are linked together one shell on top of another to
create various generations of the dendrimer. Typically identical mesogenic
units are located at the surface to the dendritic scaffold, thereby creating
a dendritic liquid crystal, or a polypedal (an object having many feet which
are the same) supermolecule. Alternatively, if the mesogenic units are mostly
different with respect to one another, then the supermolecule will have many
different feet, and thus could be termed a multipedal supermolecule. There
is a clear distinction between these two types of supermolecular system; the
polypedal supermolecule, like a polymer, can be subject to polydispersity,
whereas the multipedal supermolecular material is not; it can be similar in