Mixed alkyl-alkoxy triphenylenes

Liquid crystal formation in triphenylenes is influenced by subtle changes to the substituents attached to the core. We describe a series of triphenylenes in which 2, 4 or 6 of the alkoxy chains of parent hexa(hexyloxy)triphenylene are replaced by n-heptyl chains (giving mixed alkyl-alkoxy triphenylenes). This series permits direct comparison to derivatives which exhibit the rare helical mesophase. The syntheses have been achieved employing palladium catalysed coupling reactions in key steps. It appears, however, that incorporation of alkyl substituents suppresses mesophase formation in these materials demonstrating further the unique role played by sulfur in the helical-phase forming materials.