A ratiometric fluorescent probe for hydrazine imaging in biological and environmental samples

Hydrazine (N₂H₄) is widely used in many fields, but it is highly toxic to life when exposed to the environment. In view of this, one fluorescent probe 3HF-Br, which can produce ratio signals of absorption spectrum and emission spectrum for the detection of N₂H₄, was constructed in this work. Based on the sensing mechanism of S_N2 nucleophilic substitution - cyclization - elimination, 3HF-Br has sensitive spectral response to N₂H₄ via ESIPT effect. After the reaction, the highest emission peak of fluorescence spectrum shifted from 501 nm (cyan blue) to 561 nm (bright green), with the ratio signal (I_561/501 nm) increased by about 10 time. For N₂H₄ detection, 3HF-Br has high sensitivity and low detection limit (0.184 µM), and the maximum ratio reached at 17 min. In addition, it also showed high selectivity for the detection and is not disturbed by other nucleophilic substances. It is worth mentioning that under the ratio signal, the probe 3HF-Br can effectively monitor and image N₂H₄ not only at the cellular level but also in zebrafish. In addition, the probe 3HF-Br can also effectively respond to N₂H₄ in various soil and water samples in practical environments.