Modifications of the mesophase formation of discotic triphenylene compounds by substituents

Columnar discotic carboxylic esters of 2-hydroxy-3,6,7,10,11-penta(1-pentyl oxy) triphenylene, characterized by a variety of functional groups, were pr epared with the purpose of studying the effects of the substituents on the mesophase behaviour. Bulky substituents and polar substituents were found t o destabilize the columnar mesophase. The clearing temperature is lowered a nd the melting point of the crystalline phase, as well as the tendency to c rystallize from the mesophase. is increased. Specific substituents cause th e formation of novel discotic mesophases characterized by a superstructure.