A naphthalimide-based probe for phosgene sensing based on the phosgene-induced beckmann rearrangement

A new probe for selective and sensitive phosgene sensing in acetonitrile was developed. The sensing mechanism was based on the mechanism of the phosgene-induced Beckmann rearrangement of the naphthalimide fluorophore. An electron-withdrawing ketoxime, which was used as the phosgene receptor, was attached to the 4 position on the 1,8-naphthalimide chromophore to constituted a nonfluorescent probe. The reaction of phosgene with ketoxime induced a Beckmann rearrangement, which was followed by conversion of the nonfluorescent probe into the 4-acetamido-1,8- naphthalimide fluorophore, which emits bright blue fluorescence at 488 nm. The probe exhibited a detection limit of 6.3 nM for phosgene. In addition, the probe-loaded filter stripe for successful monitoring of gaseous phosgene was also demonstrated.