A fluorescent probe based solid-state fluorophore for the detection of N₂H₄ and its application in environmental...

Hydrazine (N₂H₄) is highly toxic, causing severe harm to water, plants, animals and other environmental systems. At present, the majority of fluorescent probes designed for N₂H₄ sensing predominantly rely on water-soluble fluorophores. These molecules tend to disperse in aqueous environments, thereby constraining their utility in environmental contexts. In this paper, a fluorophore (HPQ-IM-OH) in solid state was synthesized. Then, a fluorescent probe (HPQ-IM-S) recognizing N₂H₄ was constructed by combining HPQ-IM-OH with the 2-thiophenecarboxylate group. The probe itself does not emit fluorescence. Upon addition of N₂H₄, the 2-thiophenecarboxylate moiety is cleaved. This event halts the photoinduced electron transfer (PET) and activates the excited-state intramolecular proton transfer (ESIPT) process, thereby generating a strong fluorescent signal. HPQ-IM-S possesses the advantages of exceptional sensitivity, excellent selectivity, and prolonged imaging time. HPQ-IM-S can detect the N₂H₄ content in various kinds of water (drinking water, tap water, lake water, river water), plants (mung bean sprouts, Arabidopsis thaliana) and animals (cells, mice) for long periods of time.