An AIE+TICT activated colorimetric and ratiometric fluorescent sensor for portable, rapid, and selective detection of phosgene

Colorless and highly toxic phosgene has long been considered to be a great menace to human health and national security. Excellent AIE + TICT characteristic ratiometric and colorimetric fluorescent sensor TPE-CI was constructed with the combination of the TICT based 3-benzo[d]imidazole-chromen-2-imine unit and AIE based tetraphenylethene (TPE) unit. TPE-CI can detect phosgene not only in organic solvent through a change from the TICT process to the AIE process, but also in solid-state through a new change from the AIE + TICT process to the AIE process. TPE-CI exhibited convenient to use as a test strip, rapid response (less than 6 s in solvent and 2 min in air atmosphere), excellent selectivity and fair sensitivity for visual inspection of trace phosgene in the organic solvent and in the gas phase. The limit of detection (LOD) was calculated and derived as 0.36 μM in solvent and 0.27 ppm in the air atmosphere, which was far below the acute phosgene exposure level of human response. The satisfactory results indicate that this AIE + TICT strategy may offer valuable thinking to develop convenient solid-state optical sensors with dual ratiometric and colorimetric fluorescence response for gaseous phosgene identification.