Red-emitting rhodamine-based probe with large Stokes shift for ClO− detection

A fluorescent rhodamine dye, HN , was prepared by introducing tetrahydroquinoxalinyl donor, which displayed far-red emission (687 nm), large Stokes shift (84 nm), and relatively high fluorescent quantum yield (0.33). Based on HN dye, a fluorescent probe, HN-HClO , was developed for hypochlorite (ClO − ) detection. The probe HN-HClO exhibited fast response time (within 100 s), excellent sensitivity (LOD = 74 nM), and good selectivity toward ClO − . The probe HN-HClO was capable of imaging ClO − in both living cells and zebrafish. It could also monitor the endogenously generated ClO − in the MPO-catalyzed system. A novel far-red fluorophore HN exhibiting large Stokes shift and high quantum yield was developed by incorporating electron-donating tetrahydroquinoxaline unit into the asymmetric rhodamine dyes. Based on this elegant NIR scaffold, a new fluorescent turn-on probe HN-HClO was constructed for the detection of HOCl/ClO − . The rapid response time, excellent sensitivity and low cytotoxicity make HN-HClO capable of imaging HOCl/ClO − in aqueous solution and living cells as well as zebrafish. In addition, HN-HClO can also detect the endogenous HClO generated from the MPO-catalyzed oxidation reaction in the participation of Cl − and H 2 O 2 .