Reversible Emitting Anti‐Counterfeiting Ink Prepared by Anthraquinone‐Modified β‐Cyclodextrin Supramolecular Polymer

Intelligent fluorescent materials have been paid more and more attention due to their wide application in information encryption and anti‐counterfeiting materials. Herein, a supramolecular polymer is constructed through the host–guest interaction of anthraquinone‐modified β‐cyclodextrin (AQ‐β‐CD) in aqueous solution. Thanks to the hydrophobic microenvironment of the cyclodextrin cavity and the shielding effect on oxygen molecules, the anthraquinone group, as the guest molecule, can rapidly produce 9,10‐anthracenediol (QH(2)) with strong fluorescence by photoreduction. Interestingly, the generated anthracenediol group is still sensitive to oxygen and can be converted to anthraquinone by oxygen. Significantly, aqueous solution of AQ‐β‐CD supermolecular polymer is used as emitting ink, which decrypts the information by ultraviolet light and encrypts the information in the air.