Cucurbit[8]uril-based supramolecular self-assembly for nitrophenol adsorption

Three nitrophenol@Q[8] host-guest single crystals are obtained and fully resolved for the first time. • A laboratory-scale recyclable Q[8] adsorption-ethanol desorption procedure is developed for mixed nitrophenol removal. • Q[8]@Nitrophenol host-guest recognition is cross-validated by multiple techniques. Cucurbit[8]uril (Q[8]) was employed as an adsorbent to systematically investigate its adsorption performance, interaction mechanism, and recycling potential toward o-nitrophenol (2-NP), m-nitrophenol (3-NP), and p-nitrophenol (4-NP) in aqueous solutions. Single-crystal X-ray diffraction analysis of the Q[8]-nitrophenol assemblies revealed that π-π stacking and hydrogen-bonding interactions governed the crystalline framework. Furthermore, a cyclic adsorption–desorption process was developed, leveraging the reversible nature of the host–guest interactions, which allowed for the effective regeneration and reuse of Q[8]. After treatment with Q[8], the residual concentrations of all three nitrophenol isomers in the aqueous phase fell below the first-level discharge limit of 2.0 mg·L⁻¹.