Interface-assembled turn-on fluorescent nanofilm for highly selective detection of trifluoroacetic acid vapour via protonation modulated ICT

Abstract

Turn-on fluorescent nanofilms are attractive for gas sensing but rare, because protonation of donor–π–acceptor systems usually promotes charge separation and quenches emission. Here a gas–liquid interface-assembled DTH‑DFP nanofilm shows protonation-induced blue-shifted turn-on fluorescence to trifluoroacetic acid (TFA) vapour, offering a transparent, fast, sensitive platform (LOD 1.48 ppm).