Nitrobenzoxadiazole Ether-Based Near-Infrared Fluorescent Probe with Unexpected High Selectivity for H₂S Imaging in Living Cells and Mice

H 2 S is an important endogenous gasotransmitter, and its detection in living systems is of great significance. Especially, selective and sensitive near-infrared (NIR) fluorescent H 2 S probes with rapid response and large Stokes shift are highly desirable because of their superiority for in vivo detection. Probes with nitrobenzoxadiazole (NBD) ether as reaction sites have been well-explored recently to detect biothiols or H 2 S/biothiols simultaneously, rather than to detect H 2 S selectively. In this work, a new NBD ether-based NIR fluorescent probe was developed, which was unexpectedly found to show high selectivity for H 2 S over various other analytes including biothiols, making it practical for specific detection of H 2 S both in vitro and in vivo. Upon response to H 2 S, this probe showed rapid and significant turn-on NIR emission changes centered at 744 nm within 3 min, together with a remarkable large Stokes shift (166 nm) and high sensitivity (LOD: 26 nM). Moreover, imaging exogenous and endogenous H 2 S in living cells and rapid imaging of H 2 S in living mice with this probe was successfully applied with excellent performance.