“…To avoid a complex preparation and strict procedures, researchers who are interested in convenient detection have paid attention to fluorescent probes [ 13 ]. As reported, a typical probe includes the fluorophore (such as benzothiazole [ 14 ], 1,8-naphthalene imide [ 15 ], coumarin [ 16 ], rhodamine [ 17 ], phenothiazine [ 18 ], carbazole [ 19 ], and cyanine dye [ 20 ]) and the recognition group (such as acetyl [ 21 ], levulinate [ 22 ], 4-bromo butyrate [ 23 ], phthalimide [ 24 ], aldehyde [ 25 ], cyano [ 26 ]). As we claimed in our previous work [ 27 ], compared with complex tools (such as rare earth [ 28 ], aggregation-induced enhancement (AIE) [ 29 ], nanoparticles [ 30 ], or carbon dots [ 31 ]), small molecular probes were preferred in the closed-loop monitoring of hydrazine circulation.…”