Rational design of the ratiometric fluorescent probes for sulfur dioxide derivatives and the study on the sensing performance of cyano-containing groups

Sulfur dioxide (SO2) and its derivativeshave a close relationship with some physiological processes and many diseases. Herein, a series of fluorescent probes (named as NC1, NC2, and NC3) was rationally designed for SO2 derivatives by incorporating various cyano-containing groups to the thienocoumarin moiety. Among them, the probe NC2 with ethyl cyanoacetate moiety could ratiometrically determine SO2 derivatives with ultra-broad emission band gap (211 nm), high selectivity, excellent sensitivity, and fast optical response. More importantly, the cell imaging experiments demonstrated that the probe NC2 could be utilized as a powerful chemical tool for ratiometric visualizing SO2 derivates in biological systems.