A novel "Turn-Off-On" fluorescent probe for specific sequential detection of Cu²⁺ and glyphosate and its application...

As common pollutants, Cu²⁺ and glyphosate pose a serious threat to human health and the ecosystem. Herein, a fluorescent probe (E)-7-(diethylamino)-N'(4-(diethylamino)-2-hydroxybenzyl)-2-oxo-2H chromophore-3-carbazide (DDHC) was designed and synthesised for the sequential recognition of Cu²⁺ and glyphosate. DDHC has the advantages of a short synthesis path, easy-to-obtain raw materials, good anti-interference ability, and strong stability. The interaction of the DDHC-Cu²⁺ complexes with glyphosate allows the amino and carboxyl groups in glyphosate molecules to coordinate with Cu²⁺ strongly, competing for the Cu²⁺ in the DDHC-Cu²⁺ complexes and releasing the DDHC, leading to the recovery of fluorescence. The recognition was further validated through Job's plot, HRMS, and DFT calculations. In addition, the successful recovery of Cu²⁺ and glyphosate in different environmental water samples fully demonstrates the practical application potential of DDHC. Especially, DDHC has low cytotoxicity and can enter zebrafish and HeLa cells, rapidly reacting with Cu²⁺ and glyphosate in the body, generating visible fluorescence quenching and recovery phenomena, achieving real-time visual monitoring of exogenous Cu²⁺ and glyphosate in zebrafish and HeLa cells. The targeting and dual selectivity of DDHC greatly enhance its potential application value in the field of detection, providing important theoretical support for studying the fate of multiple pollutants in the environment.