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Two series of o-diamidobenzenes, bearing long-chain alkyl substituted gallic ester groups, have been synthesised. The 3,4,5,6-unsubstituted amides 7 with a minimum chain length of C9 exhibited columnar rectangular mesophases of p2mm symmetry with Z = 2. The liquid crystalline phases spread over phase width of extremely wide temperature intervals from -50 to 118°C. However, the phase width slightly decreased with an increase in the length of alkyl substituents. Despite their very similar molecular structure, 1,2-dimethoxy-4,5-diamides 10 revealed a different packing behaviour in their mesophases, due to steric factors. The diamides 10 formed columnar rectangular mesophases with p2mm symmetry, but with Z = 3. In a comparison with unsubstituted analogues 7, compounds 10 displayed even broader mesophases (with temperature intervals up to 220°C). [ABSTRACT FROM AUTHOR]

New imidazolium salts bearing substituted 5-phenylpyrimidine mesogenic groups were synthesised and their mesomorphic properties were studied by differential scanning calorimetry, optical microscopy and powder X-ray diffraction methods (WAXS, SAXS). The parent 5-phenylpyrimidines with the terminal bromide group at the alkoxy spacer exhibited low clearing points and smectic mesophases in narrow temperature ranges. The incorporation of the N-alkylimidazolium cationic core, connected with 5-phenylpyrimidine via an alkoxy spacer, remarkably improved the stability of the mesophases. The imidazolium salts with 5-phenylpyrimidine group formed smectic A phases, stable over broad temperature intervals. The influences of the counteranion, the length of terminal alkyl group and alkoxy spacer on the mesomorphic behaviour of the 5-phenylpyrimidine substituted N-alkylimidazolium salts were investigated in detail. [ABSTRACT FROM AUTHOR]

The last five years' achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed. [ABSTRACT FROM AUTHOR]