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Star-shaped nonaalkoxy-1,3,5-triphenyltriazines were prepared and their mesomorphism was investigated by differential scanning calorimetry (DSC), polarised optical microscopy (POM) and X-ray diffraction (WAXS and SAXS). Compounds with chain lengths C9 – C12 displayed enantiotropic hexagonal columnar mesophases over a wide range of temperature. Their similarity in molecular size and mesomorphism prompted us to study their binary mixtures with previously reported planar 1,3,5-triphenylboroxines and propeller-shaped 1,3,5-triphenylbenzenes. All three compounds are fully miscible in their hexagonal columnar mesophases, but mixtures of planar with propeller-shaped compounds generated columnar stacks that contain only one type of molecule to avoid their shape incompatibility. However, the two types of columnar stacks were fully miscible which circumvented macroscopic phase separation. [ABSTRACT FROM AUTHOR]

A small series of dendrimers consisting of a star-shaped triphenylbenzene core unit and bulky lateral groups was synthesised and their mesomorphic properties were investigated via differential scanning calorimetry, polarising optical microscopy and small- and wide-angle X-ray scattering (WAXS). The dendrimers showed two enantiotropic hexagonal columnar mesophases. The combination of temperature-dependent and fibre-extruded WAXS revealed a helical arrangement in the low-temperature and a zig-zag orientation in the high-temperature mesophase. Furthermore, at the mesophase-to-mesophase transition, the intracolumnar reorganisation and the intercolumnar lattice extension occurred at different time scales, with the latter process being the slower one. [ABSTRACT FROM AUTHOR]

Discotic liquid crystals are promising materials for electronic device applications. Combining extended π-systems with crown ethers may further open access to functional supramolecular hybrid materials. In the present publication, we briefly summarise recent literature developments and focus in a second part on our work in the field of discotic crown ethers. The crown ether derivatives are conveniently accessible by convergent syntheses which allow a high degree of variation with respect to side chains, mesogenic unit, size and symmetry of the crown core, metal complexation and counterion. This set of compounds provides a basis for systematic structure–property relationship investigations. Numerous experimental studies identified factors being crucial for mesophase stabilisation and geometry and furthermore led to novel room-temperature crown ether mesogens. The latter were obtained by congestion of the mesogenic units and even introduction of peripheral δ-methyl branched side chains. The formation of molybdenum clustomesogens and their application as luminescent hybrid materials is also described. [ABSTRACT FROM AUTHOR]