Naked-eye colorimetric and dual-emission ratiometric two-in-one probe based on ESIPT mechanism for hydrazine sensing in real samples and ultrafast detection of hydrazine vapor.

Abstract

Hydrazine (N2H4) is a highly toxic industrial chemical with strong carcinogenicity and environmental persistence. Its uncontrolled discharge and leakage lead to widespread contamination of water, soil, plant and food matrices, posing severe threats to ecological security and human health. Herein, a novel colorimetric and near-infrared (NIR) ratiometric fluorescent probe HBT-CN was rationally designed and synthesized based on the excited-state intramolecular proton transfer (ESIPT) mechanism for the specific detection of N2H4. HBT-CN exhibited a distinct naked-eye color change from red to green and a typical NIR ratiometric fluorescence response to N2H4, with the maximum absorption wavelength blue-shifting from 540 nm to 450 nm. HBT-CN exhibited excellent selectivity and anti-interference ability against common ions, amine compounds and biological small molecules. Notably, it was successfully applied for N2H4 detection in diverse real matrices and scenarios: qualitative/semi-quantitative detection of liquid/gaseous N2H4 via filter paper; sensitive recognition of trace N2H4 in hydroponic flowers and food samples; qualitative/quantitative analysis of N2H4 in different soil types and natural water samples. A smartphone-assisted portable sensing platform was constructed based on RGB value analysis, realizing on-site quantitative detection of N2H4 with a good linear relationship (R2 = 0.9896). Furthermore, HBT-CN possessed low cytotoxicity and good biocompatibility, enabling effective NIR fluorescence imaging of exogenous N2H4 in living HeLa cells and zebrafish models. This work provides a versatile analytical tool for N2H4 detection and a new strategy for designing ESIPT-based multifunctional probes for environmental monitoring and biological analysis.