We demonstrate a reversible shape-morphing with concurrent fluorescence switching in the nanomaterials which are complexed with cucurbit[7]uril (CB[7]) in water. The cyanostilbene derivative alone forms ribbon-like two-dimensional (2D) nanocrystals with bright yellow excimeric emission in water (λem =540 nm, ΦF =42 %). Upon CB[7] addition, however, the ribbon-like 2D nanocrystals immediately transform to spherical nanoparticles with significant fluorescence quenching and blue-shifting (λem =490 nm, ΦF =1 %) through the supramolecular complexation of the cyanostilbene and CB[7]. Based on this reversible fluorescence switching and shape morphing, we could demonstrate a novel strategy of turn-on fluorescence sensing of spermine and also monitoring of lysine decarboxylase activity.
Keywords: cucurbit[n]uril; fluorescence; host-guest complexes; self-assembly; supramolecular chemistry.
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