Molecular Entrapment of Polymers by Pyrogallol[4]arenes

Macromolecular recognition systems are difficult to construct because extremely high recognition ability is required to form a stable host–guest complex toward macromolecules. Herein, we report a novel host–guest recognition motif based on C-propylpyrogallol[4]­arene (PgC3) and a commercially available polymer, polyethylene glycol (PEG). The results show that PgC3 can selectively entrap PEG with higher molecular weights to form bilayered host–guest complex structures. Interestingly, this host–guest recognition is strong enough that PgC3 is able to adsorb PEG from an aqueous solution efficiently.