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

We report the photoresponsive self-assembly of a D-cyclodextrin derivative containing an azobenzene terminal group with an oligoethylene glycol linker (Azo-EG-beta CD). Azo-EG-beta CD 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-beta CD 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 beta-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.