The development of organic dye-based fluorescent probes for detection of H2S in living systems has attracted considerable attention in recent years. In this work, a novel tetrahydroquinoxaline iminocoumarin-based red to near-infrared (red-to-NIR) fluorescent probe was developed for detection of H2S. This probe shows a rapid and distinct red-to-NIR fluorescent turn-on detection process for H2S with high selectivity and sensitivity (the detection limit was determined to be as low as 10 nM at physiological pH). In addition, this probe exhibits a r...