The broad occurrence of the hydrazine (N(2)H(4)) residues in aqueousenvironment is a potential threat to human health. Currently, the mainstream strategy for designing N(2)H(4)-specific probes is to functionalize a fluorophore with nucleophilic sites for the reductionreaction with N(2)H(4). In this work, we designed and synthesized an excited-state intermolecular proton transfer (inter-ESPT) fluorescent dye(2-amino-4-(4-methoxyphenyl)-7,8-dihydro-5H-spiro[quinoline-6,2'-[1,3]dioxolane]-3-carbonitrilem, DQN) and used it as a probe to sense N(2)H(4). DQN exhibits blue fluorescence in conventiona...
