Zero- Fluorescence Probe for Ultrasensitive and Specific Detection of Hydrazine by Regulating the Electron-Accepting Strength

The introduction of an excited-state intramolecular proton transfer (ESIPT) process is of great significance for the design of zero-background fluorescent probes with specific functionalities. Here, based on the nucleophilic attack characteristics of N₂H₄, a series of BDMN-based probes with dicyanoethylene as the recognition site were designed by regulating the electron-accepting ability of para-substituent of the dicyanoethylene and the relative position of the hydroxyl group and dicyanoethylene. It is found that a stronger electron-accepting capability could greatly improve the reactivity of the recognition site, and only when the hydroxyl group is in the ortho-substituent of the recognition site, the probe could react with N₂H₄ to generate hydrazone as a proton acceptor, producing the ESIPT process and the blue-green fluorescence emission. The probe m-Br–OH-BDMN with Br as the electron-accepting group has better detection performance for N₂H₄, with low limit of detection (LOD, 0.46 nM), fast response (1 s), and superior selectivity even in the presence of 18 kinds of interferents. Furthermore, the practicability of the probe design strategy was further verified by the construction of a m-Br–OH-BDMN loaded silicon-based porous sensor, realizing the specific identification of N₂H₄ vapor. The present nonfluorescent probe design strategy would provide new thoughts for the rational design of functional probes as well as high-performance sensing methodologies.