Iridium(III) complex-based phosphorescent probe for rapid, specific, and sensitive detection of phosgene

Due to the high toxicity and commercial availability of phosgene, there is an urgent need for rapid and reliable detection of phosgene in order to deal with a potentially severe threat to public security caused by terrorist and accidental industrial release. In this work, an iridium(III) complex, Ir-OXIME, has been developed as a fast, highly sensitive and selective sensor for phosgene. Ir-OXIME displayed very weak phosphorescence due to quenching caused by the C=N-OH moiety. After reacting with phosgene, the oxime is converted to a nitrite to form the brightly phosphorescent product, Ir-CN. Ir-OXIME exhibited a rapid response (<5 s), a low detection limit (2.4 nM), and a high selectivity towards phosgene in solution. The Stokes shift of Ir-OXIME reaches 294 nm, which prevented signal crosstalk and consequently improved sensing accuracy. Finally, test papers with Ir-OXIME immobilized on filter paper were designed and prepared as a practical detection tool of phosgene gas.