Liquid-crystalline supramolecular polymers formed through complementary nucleobase-pair interactions

We report how the placement of nucleobase units, thymine, or N ⁶-(4-methoxybenzoyl)adenine, onto the ends of a mesogenic core, bis-4-alkoxy-substituted bis(phenylethynyl)-benzene, affects the properties of these materials. We show that addition of these bulky polar groups significantly reduces the range of liquid-crystalline behavior of these compounds. However, mixing two complementary nucleobase-containing AA- and BB-type monomer units together does result in the formation of stable, thermotropic liquid-crystalline (LC) phases. Hydrogen bonding is shown to play an important role in the formation of these LC phases, consistent with the formation of oligomeric or polymeric hydrogenbonded aggregates. X-ray analyses of these mixed materials are consistent with the formation of smectic C phases.