Manipulating Dynamic Fluorescent Emissions by Introducing SP Molecule into Functionalized HOFs and Application in Time‐Resolved Information Encryption

Abstract The powerful capability of multi‐stimulus‐responsive fluorescent hydrogen‐bonded organic frameworks (HOFs) to respond to external chemical or physical stimuli in various manners makes them appealing in advanced information encryption. However, it is still a global challenge to manipulate the fluorescence properties finely to achieve dynamic fluorescence properties in the time dimension. Here, a feasible strategy is shown to control the emission of materials by introducing a common SP photochromic compound (1′, 3′, 3′‐trimethyl‐6‐nitro‐spiro‐ [chromene‐2, 2′‐indoline]) into functionalized HOFs, to finely manipulate the fluorescence properties. Two kinds of HOFs are successfully synthesized by modifying the unbonded carboxylic group of HOFs with Tb 3+ or 5‐hexene‐1‐ol termed Tb‐HOFs and HOF‐olefin, respectively. Then, spiropyran is loaded into the Tb‐HOFs or HOFs‐olefin and dynamic fluorescence emission can be well controlled by changing the lanthanide dopants and light stimulation time. Relying on the dynamic fluorescence emission, the multilevel information encryption including anti‐counterfeiting ink, QR code, base code, and time‐resolved information storage has been successfully demonstrated, and the security level has been greatly improved. This work opens an avenue for achieving time‐resolved information storage technology, where the “time factor” is equivalent to a dynamic key, which introduces countless unpredictable possibilities and makes imitation more challenging.