PA45 Optical texture changes at the phase transitions of azobenzene-triphenylene liquid crystals exhibiting both calamitic smectic and discotic columnar mesophases

Abstract

The alkyl homologues of azobenzene-triphenylene mesogen (1C-n: n=11-16) exhibit both thermal and photo-induced phase transitions among calamitic smectic and discotic columnar mesophases with the change of molecular anisotropy. However, one can see the difference in phase transition parameters between the shorter (1C-11 and 12) and longer (1C-13〜16) homologues. The optical texture observations of these homologues on a glass and polyimide-coated substrates indicated that the molecular conformation (relative positioning) of the azobenzene moieties and the central triphenylene differs with a critical point of the alkyl chain length between 1C-12 and 13.