Smart Photoresponsive Label with Red Fluorescence and Blue Phosphorescence Promoted by Hydrogen-Bonded Organic Frameworks for Food Additives Detection

The photoresponsive materials with excellent sensing performance have garnered increased attention in the field of smart food labels. Owing to exceptional optical properties, room-temperature phosphorescent (RTP) materials gradually grow as promising candidates. While the unstable and sensitive triplet excitons impede the development of purely organic RTP materials. Herein, a host–guest doping strategy is proposed to promote RTP through the encapsulation of organic phosphors with different carboxyl positions into hydrogen-bonded organic frameworks (HOFs) via in situ assembly. The rigid environment provided by HOFs effectively stabilizes triplet excitons of the guest to achieve blue RTP with a long lifetime of 235.6 ms. Furthermore, a dual-emission material (Eu-TMLA@HOF) combining red fluorescence and blue phosphorescence demonstrates high sensitivity, excellent selectivity, and a rapid response in detecting food additives. Furthermore, the Eu-TMLA@HOF hydrogel was designed to underscore its potential as a robust and efficient photoresponsive label for monitoring food additives.