Photoresponsive self-assembly of a β-cyclodextrin derivative with an azobenzene terminal group in water

Abstract

We report the photoresponsive self-assembly of a β-cyclodextrin derivative containing an azobenzene terminal group with an oligoethylene glycol linker (Azo-EG-βCD). Azo-EG-βCD was synthesized, and its aggregation was investigated using several techniques including TEM analysis, DLS and other spectral measurements. In a freshly prepared aqueous solution, Azo-EG-βCD self-assembled into a network-like structure by forming intermolecular host–guest inclusions that transformed into vesicles upon aging because of hydrogen bonding. Transformation from trans-azo to cis-azo using UV light induced the dissociation of azobenzene in the β-CD cavity, and the aggregate transformed into vesicles. The construction of a photoresponsive self-assembly may provide a unimolecular host–guest complexation model in stimuli-responsive host–guest self-assembly.