Abstract：A nearinfrared region （NIR） ratiometric fluorescent probe 1 was constructed based on flavylium derivative to monitor and image exogenous and endogenous H2S in living cells. The results show that when H2S is added, the nucleophilic addition of H2S to the benzopyran portion of the probe molecule 1 can destroy the conjugate system, resulting in the reduction of near infrared (NIR) emission at 720 nm. The green fluorescence at 503 nm is significantly enhanced because the adduct contains a complete semirigid coumarin fluorescence group. Due to the different emission wavelength of probe 1 with that of semirigid coumarin, there are two completely separated emission peaks before and after adding H2S, and the effective ratio detection of H2S is realized. In the presence of 4.0 μmol·L-1 of H2S, a 19.2fold fluorescence intensity enhancement is occurred. Probe 1 shows a good linearity with H2S when it ranges from 0.1 mol·L-1 to 4.0 μmol·L-1 with R2 of 0.993 9, and the detection limit is 57.8 nmol·L-1. The probe 1 can be sensitive to H2S with response time of only 110 seconds and good selectivity. The probe 1 can be successfully applied to fluorescence imaging of endogenous and exogenous H2S in living cells.
