A novel D-π-A molecule as ICT type fluorescent probe for endogenous hypochlorite imaging in living cells and zebrafishes

In order to explore the application of D-π-A molecules in bio-imaging, two novel D-π-A and ICT type molecules (SE and PE) are designed and synthesized by the adjustment of the π conjugation bridge. Because of strong intramolecular charge transfer (ICT) effect between the carbazole and pyrimidine unit, SE and PE exhibit weak fluorescence emission in the aqueous solution system. Interestingly, SE shows the enhanced fluorescence detection performance for hypochlorite due to “D-π-A" structure and suitable ICT effect after the oxidative cleavage of alkene unit by hypochlorite. Importantly, the cell membrane permeable SE can be used for the exogenous and endogenous ClO− in living cells and zebrafishes without apparent toxicity before and after treating with ClO−. Our study indicates that regulating “D-π-A" structure and suitable ICT effect of the organic fluorescence probes is a powerful method to enhance their detection performance for the target analyte.