Efficient Multi-stimulus-Responsive Luminescent Eu(III)-Modified HOFs Materials: Detecting Thiram and Caffeic Acid and Constructing a Flexible Substrate Anti-counterfeiting Platform.

The powerful capability of multi-stimulus-responsive luminescent hydrogen-bonded organic frameworks (HOFs) to respond to external chemical or physical stimuli in various manners makes them appealing in the luminescence anti-counterfeiting field. Herein, a novel Eu-functionalized HOF (Eu@GC-2) that combines the emission of HOFs with the characteristic emission of Eu ions has been successfully synthesized, which can generate various fluorescence at different excitation wavelengths. Eu@GC-2 has enormous potential as a raw material for a paper-based sensor that is designed for detecting the pesticides thiram and caffeic acid in crops with favorable selectivity, anti-interference, and high efficiency. Based on the above excellent properties, Ln-functionalized HOFs (Ln@GC-2) were then employed to produce four luminescent anti-counterfeiting inks. With the incorporation of back-propagation neural network and Gray code conversion functions, a multi-stimulus-responsive luminescent anti-counterfeiting platform, coregulated by the excitation light and the chemical reagent, has been constructed. This approach can not only achieve multiple encryptions and fast information identification but also enhance the code-breaking complexity, making it an efficient strategy for information encryption and decryption.