Photoresponsive Supramolecular Systems: Self-Assembly of Azodibenzoic Acid Linear Tapes and Cyclic Tetramers



A new strategy to effect photoinduced control over molecular self-assembly is reported. This strategy uses the reversible transcis photoisomerization of a novel azobenzene system, where the trans- and cis-forms self-assemble into dramatically different higher-order structures. The trans-azobenzene form of this molecule associates into infinite hydrogen-bonded linear tapes, while the cis-azobenzene form undergoes hydrogen-bonded self-assembly into cyclic tetramers. This results in a second level of association, where the cis-hydrogen-bonded supramolecular cycles ultimately form long, rod-like aggregates through stacking interactions.