Columnar liquid crystals polycatenars

While it is in discotic liquid crystals that the formation of columnar phases is most readily recognized supra), there exists a family of non-disk-like mesogens, the polycatenar liquid crystals, where these mesophases are also formed extensively. As will be seen from their shape, this observation is of some interest, but it is the fact that certain polycatenar materials can, within a homologous series, show mesomorphism characteristic of both rod-like and disklike mesogens that makes them particularly interesting. 

The same type of columnar structure is also proposed for other polycatenar materials, such as tetrone derivatives [51], phasmidic macrocyclic liquid crystals [52], silver (I) complexes [53], or 2,2 -bipyridine derivatives [54]. 

While it is in discotic liquid crystals that the formation of columnar phases is most readily recognized (vide supra), there exists a family of non-disk-like mesogens, the polycatenar liquid... 

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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