Phasmidic phases in macrocyclic liquid crystals

In this article we describe the synthesis, characterisation and phase behaviour of some phasmidic liquid crystals containing the diaza 18-crown-6 macrocyclic core. Seven compounds were synthesised, five tetracatenar and two hexacatenar. The terminal alkoxy chains were varied in length from ten to eighteen carbon atoms, and the number of phenyl rings in the mesogenic units was set at either two or three. Depending on the nature of the mesogenic moiety, hexagonal columnar phasmidic and smectic phases were found to occur for these systems. The natures and structures of the columnar phases found for these systems are discussed in relation to the conformational structure of the macrocyclic core and to the overall geometry, shape and flexibility of the molecular structures.