Solid AIE fluorophore molecule with specific response of amide functional group to detect gaseous phosgene

A new solid Aggregation-induced Emission (AIE) fluorophore molecule (Ind-CONH2) for specific response of gaseous phosgene based on the dehydration of primary amide to nitrile was designed. Specially, visible AIE color changes of Ind-CONH2 with phosgene could be observed directly from bright blue to greenish blue on a portable solid-state test-strip under a 365 nm ultraviolet (UV) lamp, which showed inverse color changes from colorless to bright blue in homogeneous acetonitrile solution due to intramolecular charge transfer (ICT) effect. LOD of Ind-CONH2 for phosgene in acetonitrile was 1.52 nM and that for gaseous phosgene was 0.16 ppm (response time was less than 10 s in acetonitrile and 3 min for gas), which had a good development prospect in detecting phosgene. Additionally, Ind-CONH2 was successfully used as an erasable fluorescent anti-counterfeiting ink.