Applicable Properties of Columnar Discotic Liquid Crystals

Chapter IX Applicable Properties of Columnar Discotic Liquid Crystals.781... 

Understanding the organization of disc-shaped mesogens in columnar phases is of practical interest because of their useful optoelectronic applications [168-170]. It will be instructive to explore the role of fluctuations in influencing transport properties of thermotropic discotic liquid crystals—in particular, in the columnar phase. 

We start by reminding ourselves that columnar discotic liquid crystals are comprised of disordered stacks (1-dimensional fluids) of disc-shaped molecules arranged on a two-dimensional lattice (Fig. 1) [1]. This structure imparts novel properties to these materials from which applications are likely to stem. One such property is the transport of charge along the individual molecular stacks [2-7]. The separation between the aromatic cores in, for example, the hexa-alkoxytriphenylenes (HATn), the archetypal columnar discotic mesogen, is of the order of 0.35 nm, so that considerable overlap of n orbitals of adjacent aromatic rings is... 

Thus, supermolecular liquid crystals with a cyclotriphosphazene dendritic core and polycatenar mesogenic units (144) were obtained in three steps by the conventional sequence of substitution (i), derivatization (ii and iii) methods from [N3P3CI6] (Scheme 9). Due to the microsegregation of the alkyl chains and the aromatic central cores and the space-filling properties, compounds (144) adopt a discotic conformation assembled in a columnar mesophase and illustrate the possibilities of using cyclotriphosphazenes for the design of columnar assemblies at room temperature, in the mesophase or in a vitrified solid state with interest for applications in material science. Similarly, the new family of solution processable, photoluminescent, monodisperse nanocomposite dendrimers (145) (Tg > 165 °C, > 465 °C)... 

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