An Effective Fluorescence Sensor for Herbicide Haloxyfop-P-Methyl Based on Cyclic Bicyanostilbene Imidazole Salt

Abstract

Haloxyfop-P-methyl is a widely used herbicide, but no facile and on-site detecting method for haloxyfop-P-methyl was presented up to now. In this work, the first fluorescent sensor for haloxyfop-P-methyl was developed based on a cyclic bicyanostilbene imidazole salt (CBIS). CBIS was prepared by “1+1” condensation of a bicyanostilbene imidazole derivative with a chiral (1S, 2S)-cyclohexanediamine derivative in 68% yield. It possessed the weak green fluorescence at 514 nm in aqueous media, but the strong blue fluorescence at 493 nm after sensing haloxyfop-P-methyl. This “turn-on” fluorescence and color change was only observed for detecting haloxyfop-P-methyl among various pesticides and ions. The detecting limitation was as low as 1.41×10-8 M. The binding mechanism was clarified as that haloxyfop-P-methyl was encapsulated in the cavity of CBIS. The fluorescence sensing ability of CBIS was successfully used on detecting haloxyfop-P-methyl in the experiments of test papers, the real samples of apples and oranges, and simulated water samples, supporting the good application prospect for facile and on-site sensing haloxyfop-P-methyl in real samples of fruits and foods.

Keywords: Fluorescence, Sensor, bicyanostilbene, haloxyfop-P-methyl, Selectivity, Sensitivity