For the nitroreductase assay, 2,3 fluorescence spectroscopy has attracted much attention because of its great temporal and spatial sampling capability as well as high sensitivity. Several fluorescent nitroreductase probes have been developed by employing the enzymatic reduction of nitroaromatic compounds. 2,3 For instance, Huang et al. synthesized a fluorescence off–on probe by attaching 4-nitrobenzene to coumarin with a diamine linker, and Qian et al. prepared a novel ...