Construction of a room-temperature phosphorescence system by cucurbit[8]uril-based supramolecular assembly

A bromophenylpyridine derivative (BH-PY) was designed and synthesized as the guest molecule included in the cavity of cucurbit[8]uril (CB[8]) to form a 2:1 host–guest complex, which displays good room-temperature phosphorescence (RTP) in aqueous solutions. The interaction and optical properties of CB[8] with a guest in aqueous solution were investigated using 1 H NMR spectroscopy, UV–Vis absorbance spectra, fluorescence and phosphorescence spectra and X-ray diffraction analysis in detail. The result showed that the bromophenyl moieties of the two guest molecules are included in the cavity of the CB[8] in a ‘head-to-tail’ stacking way, whereas the other part of BH-PY remains outside the portal to form a 2:1 supramolecular structurce, and supramolecular assemblies were applied for targeted phosphorescent imaging of mitochondria.