An ultrasensitive fluorescent probe for phosgene detection in solution and in air

In this work, an ultrasensitive fluorescent turn-on probe (HBT-Phos) for rapid detection of the highly toxic phosgene is reported. This probe uses 2-(2'-hydroxyphenyl)benzothiazole (HBT), a well-known excited-state intramolecular proton transfer (ESIPT) dye as the fluorophore and an oxime moiety as the reaction site. Upon addition of various analytes, this probe specifically reacts with phosgene to release a highly fluorescent nitrile product (HBT-CN) via a dehydration process, which provides a new selective and ultrasensitive fluorescent turn-on detection method for phosgene (F/F-0 similar to 1750-fold, detection limit similar to 0.48 nM in solution). Furthermore, using the aggregation-induced emission (AIE) of the product in solid state, this probe was successfully applied to prepare a silica plate-based portable sensing system for detecting phosgene gas in air with a detection limit as low as similar to 0.34 ppm. All the results indicate that this probe is of great value for on-site detection of phosgene.