Dual Recognition\nExhibiting a Polymeric Fluorescent\nProbe for Specific Detection and Removal of Hydrazine

Sensitive and specific detection of hydrazine (N<sub>2</sub>H<sub>4</sub>) is of great importance for environmental ecology\nand human\nhealth due to its high biotoxicity. However, the selectivity of most\nexisting N<sub>2</sub>H<sub>4</sub> probes relies on the reaction\nwith one of the nucleophilic groups (−NH<sub>2</sub>) of N<sub>2</sub>H<sub>4</sub>, which cannot effectively discriminate N<sub>2</sub>H<sub>4</sub> from other amino compounds. Herein, we report\na coumarin-appended polymeric probe (CFPF) for the selective detection\nand removal of N<sub>2</sub>H<sub>4</sub> in water solutions. By cross-linking\naldehyde-coumarins with the acetylphenyl moieties on polystyrene,\nthe polymeric multivalent probe was obtained, which endowed the polystyrene\nwith excellent fluorophores and multiple electrophilic sites for special\nreaction with N<sub>2</sub>H<sub>4</sub>. In the presence of various\ncompetitive species, CFPF offers highly sensitive, specific, and rapid\nresponse to N<sub>2</sub>H<sub>4</sub>. The preliminary mechanism\ninvestigation revealed that the change in optical signal resulted\nfrom N<sub>2</sub>H<sub>4</sub>-mediated chalcone or chlorobuta-1,3-diene\ncyclization. The CFPF-based method for detecting N<sub>2</sub>H<sub>4</sub> gives a limit of detection (LOD) of 4.19 nM, which is lower\nthan that suggested by USEPA (TLV, 10 ppb). Furthermore, a CFPF-loaded\nbead device was fabricated and used to monitor and extract N<sub>2</sub>H<sub>4</sub> in the wastewater samples. The reaction-specific and\nstable characteristics of CFPF-beads led to the extraction of trace\nN<sub>2</sub>H<sub>4</sub> from the water body. Overall, the proposed\npolymeric probe indicates its potential application for N<sub>2</sub>H<sub>4</sub> sensing and trapping in water samples and represents\na prospective multivalent probe for practical applications.