A two-photon fluorescent probe for specific detection of hydrogen sulfide based on a familiar ESIPT fluorophore bearing AIE characteristics.

Hydrogen sulfide (H2 S) is a signaling gasotransmitter, which plays various roles in modulating the functions of different systems. In this study, a "turn-on" fluorescent probe for H2 S was developed. The probe, whose design is based on a familiar excited state intramolecular proton transfer (ESIPT) fluorophore bearing aggregation-induced emission (AIE) characteristics, was found to exhibit an 80-fold fluorescence enhancement along with a large Stokes shift upon the addition of H2 S. Furthermore, the probe was successfully utilized to detect H2 S in HeLa cells with both one-photon and two-photon microscopy.