A sensitive and selective fluorescent probe for the detection of hydrogen peroxide with a red emission and a large Stokes shift

Using aromatic boronic ester as sensing unit, a red-emitting fluorescent probe, 1, for H2O2 detection has been developed based on an ESIPT fluorescent dye, 4 (1,3-bis(bispyridin-2-ylimino)isoindolin-4-ol). The aromatic boronic ester moiety masked the hydroxy group in dye 4 to inhibit the ESIPT process and quench its fluorescence. The addition of H2O2 cleaved the sensing group in Probe 1 and subsequently resulted in the formation of fluorescent dye 4. This probe displayed a large Stokes shift (217 nm) in the detection of H2O2 and the detection limit was calculated to be 9.1 nM based on S/N = 3. Furthermore, this probe was successfully applied to detect intracellular H2O2 in living 4T1 cells.