Smart PhotoresponsiveLabel with Red Fluorescenceand Blue Phosphorescence Promoted by Hydrogen-Bonded Organic Frameworksfor 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.