A dual pyridinium-tetraarylimidazole fluorescent sensor for the detection of the herbicide quizalofop-p-ethyl

Abstract

Quizalofop-p-ethyl is a highly effective herbicide, but threatens both human health and environmental safety when improperly used. Therefore, a simple and in situ method for detecting quizalofop-p-ethyl is urgently required. In this work, we designed and synthesized a dual pyridinium-tetraarylimidazole (DPT) via a simple and straightforward synthetic route. Upon binding quizalofop-p-ethyl, DPT exhibits a turn-on blue-green fluorescence response. High selectivity was demonstrated across 28 different herbicides and ions. The probe shows good linearity over a quizalofop-p-ethyl concentration range of 0–0.1 equiv., with a limit of detection of 1.05 × 10⁻⁷ M. Mechanistic studies indicate that the turn-on fluorescence could be attributed to the strong molecular interaction based on hydrogen bonding, electrostatic interaction, π–π stacking and hydrophobic interaction between the host and guest. The sensing capability of DPT has been successfully validated in test-strip assays, soil detection, plastic films and simulated water samples, demonstrating that this sensor enables simple, rapid, and on-site detection of quizalofop-p-ethyl in complex environments.