New mesogenes forming nanophase separated liquid crystalline structure - Cubic phase

Hydrogen bonded complexes between 4-(oligodimethylsiloxyl)alkoxy benzoic acids and 4,4'-dipyridyl were found to exhibit a thermotropic liquid crystalline cubic phase. One of the important factors to realize the cubic structure could be the incompatibility between the flexible, bulky siloxane moiety and the rigid mesogenic core, which probably causes nanophase separation. We have investigated benzoic acid derivatives having a polar, relatively rigid perfluorinated alkyl segment that also exhibits incompatibility with hydrocarbon parts. The neat acids and their hydrogen bonded complexes with 4,4'-dipyridyl does, however, not show thermotropic liguid crystalline cubic phase, but a smectic A phase. In this paper we will consider the chemical prerequisite to realize a thermotropic cubic phase.