An effective dihydroxanthene-based fluorescent probe for phosgene visual detection in solution and gaseous phases.

Real-time monitoring of phosgene is of great significance for public health and environmental safety. To achieve this goal, a strategy was proposed to construct a probe structure featuring long excitation/emission wavelengths and high fluorescence quantum yield by introducing receptors with different electron-withdrawing abilities to regulate intramolecular charge transfer (ICT). Based on this, a class of fluorescent probes based on dihydroxanthene dyes DHX-Phos-Pyr (Q.Y. = 7.91%, DHX-Phos-BZT Q.Y. = 4.70%) were designed and synthesized for the visualization and fluorescence analysis detection of phosgene. Through comparison, it was found that DHX-Phos-Pyr exhibited high selectivity and sensitivity, with response time of less than50 s detection limit of 32 nM in solution and gaseous phosgene detection limit of 0.31 ppm. The strong color difference and macroscopic red color have the function of stimulating people's senses and emotions. DHX-Phos-Pyr exhibits a clear color change from yellow to pink for the identification and analysis of phosgene solution by naked eye, and under 365 nm conditions, it displays a bright red color after responding to phosgene, serving as a strong warning. In addition, test strips loaded with DHX-Phos-Pyr were prepared and shown to possess practical utility for the sensitive fluorescence detection of phosgene.