A red to near-infrared fluorescent probe featuring a super large Stokes shift for light-up detection of endogenous H2S

In this work, a new reaction-based red to near-infrared (NIR) fluorescent turn-on probe for H2S was developed. This probe uses a readily prepared dicyanoisophorone as the fluorophore and a 2, 4-dinitrobenzenether with an ortho-aldehyde group as the reaction site. Upon addition of H2S, a fast nucleophilic addition of H2S to the aldehyde group and a following efficient intramolecular thiolysis of dinitrophenyl ether occurred, which leads to release the fluorophore and give a rapid NIR fluorescence turn-on response for H2S with a super large Stokes shift (244 nm). The fluorescence enhancement was found up to 105-fold and the detection limit was determined to be as low as 42 nM. Importantly, this probe shows high selectivity and sensitivity for H2S without interference from biothiols. Furthermore, NIR fluorescent imaging of exogenous and endogenous H2S in living cells with this probe was also successfully applied. All the results indicate that this probe is excellent and highly valuable.