Near-infrared Rhodols-based fluorescent probe with large Stokes shift for tracking of HS in food spoilage and living cells.

Hydrogen sulfide (HS), as a biomarker signaling gas, is not only susceptible to food spoilage, but also plays a key function in many biological processes. In this work, an activated near infrared (NIR) HS fluorescent probe was designed and synthesized with quinoline-conjugated Rhodols dye as fluorophore skeleton and a dinitrophenyl group as the responsive moiety. Due to the quenching effect of dinitrophenyl group and the closed-loop structure of Rhodols fluorophore, probe itself has a very weak absorption and fluorescence background signal. After the HS-induced thiolysis reaction, the probe exhibits a remarkable colormetric change and NIR fluorescent enhancement response at 716 nm with large Stokes shift (116 nm), and possesses high sensing selectivity and sensitivity with a low detection limits of 330 nM. The response mechanism is systematically characterized by H NMR, MS and DFT calculations. The colorimetric change allows the probe to be used as a test strips to detect HS in food spoilage, while NIR fluorescent response helps the probe monitor intracellular HS.