BODIPY-based asymmetric monosubstituted (turn-on) and symmetric disubstituted (ratiometric) fluorescent probes for selective detection of phosgene in solution and gas phase

Here, we designed and synthesized two fluorescent probes for detecting phosgene by nucleophilic substitution reaction using BODIPY as a fluorophore and 2-aminobenzylamine as reactive functional group. For the first time, we have studied the similarities and differences between asymmetric monosubstituted (1) and symmetric disubstituted (2) probes. A monosubstituted probe 1 (having a 2-aminobenzylamine group at the 3-position of BODIPY) has fluorescence-enhancing (weak green fluorescence to strong green fluorescence) responce to phosgene in 30 s with a large Stokes shift (∼70 nm) and sensitive property (DL = 0.81 nM); while the disubstituted probe 2 (having two 2-aminobenzylamine groups at the 3, 5-position of BODIPY) has a ratiometric fluorescent responce to phosgene in 2 min. The linear range of the response is wider than that of the monosubstitution probe 1, and the detection limit is also lower (2.36 nM). In addition, probes 1 and 2 can effectively eliminate the interference of other substances with similar chemical structure as phosgene. They can not only detect phosgene in solution environment, but also in gaseous environment quickly and sensitively.