Ratiometric fluorescent probe for highly selective detection of gaseous H₂Se

H₂Se has been widely applied, and its release will cause serious human health and environmental effects. It is urgent to develop facile tool and reliable method for the determination of H₂Se. Here, we introduce a concisely synthesized molecular HBT-Se, with a specially designed H₂Se trapper 2-(iodomethyl)benzoate and a typical ESIPT fluorophore. The free HBT-Se exhibited blue fluorescence owing to the blocked ESIPT (exited state intramolecular proton transfer) process, while the 2-(iodomethyl)benzoate group could undergo a cascade reaction with H₂Se, unblocking the ESIPT process and bathochromically shifting fluorescence response. The sensing mechanism was also rigorously verified by ¹H, ⁷⁷Se NMR and MS analyses. Additionally, HBT-Se features a sensitive, selective and quantitative determination of H₂Se. With these satisfied properties, HBT-Se was further applied as a paper-based sensor for detection of gaseous H₂Se, and the enhanced performances of HBT-Se will promote its potential value in further study of H₂Se in environmental pollutant.