A ‘‘naked-eye’’ colorimetric and ratiometric fluorescence probe for trace hydrazine

Abstract

Hydrazine (N₂H₄) is widely used in industry but also very toxic. Herein, we describe the preparation of a ‘‘naked-eye’’ colorimetric and ratiometric fluorescent probe (DH), bearing α,β-unsaturation carbonyl group as a recognition site, and employ it for the excited-state intramolecular proton transfer based (ESIPT-based) detection of N₂H₄. The probe can detect N₂H₄ by colorimetric and ratiometric fluorescence dual signals with high sensitivity and selectivity; the detection limit of N₂H₄ was 0.063 μM (2.01 ppb), which was far below the safety level (10 ppb) stated by the U.S. Environmental Protection Agency (EPA). It enables “naked-eye” detection for hydrazine determination in aqueous solution. More importantly, we successfully applied DH to detect N₂H₄ in real water samples, indicating its potential utility for N₂H₄ sensing in environmental samples.