Thermotropic liquid crystals of 1H-imidazole amphiphiles showing hexagonal columnar and micellar cubic phases

• DOI: 10.1016/j.tetlet.2007.07.187
• Publication Date: 2007-08-02T11:27:04Z
• Authors: Sang Hyuk Seo; Jun Ha Park; Gregory N. Tew; Ji Young Chang
• Keywords: Thermotropic crystal; Hexagonal phase; Imidazole; Columnar phase

Abstract The linear and polycatenar type 1 H -imidazole amphiphiles showing a strong self-assembly tendency to build various supramolecular structures in bulk were synthesized by the esterification reaction of 4′-alkyloxy phenols (for 1 – 4 ) and hydroxyphenyl trialkyloxybenzoates (for 5 – 7 ) with 4-chlorocarbonyl imidazole. The linear 1 H -imidazole amphiphiles formed thermotropic smectic phases, but compound 4 with an ethyl group instead of hydrogen on 1 N did not show a mesophase. The polycatenar type 1 H -imidazole amphiphiles ( 5 – 7 ) formed thermotropic hexagonal columnar and cubic phases. A phase transition was observed from a columnar phase to a cubic phase as the temperature increased on heating, and vice versa on cooling. In the POM study for compounds 5 – 7 , optically isotropic phases first appeared on cooling from the isotropic melts, and then birefringent mesophases with a nonspecific texture appeared on further cooling. The X-ray analysis shows that the optically isotropic phases were very likely micellar cubic phases with Pm 3 n symmetry. The birefringent phases were confirmed as hexagonal columnar phases.