A ratiometric fluorescent probe with a large Stokes shift for the detection of Hg2+ and its applications in environmental sample and living system analysis

Abstract

Toxic mercury ions (Hg²⁺) can cause serious environmental pollution and accumulate in living organisms via the food chain. Therefore, monitoring Hg²⁺ is crucial in ensuring the safety of ecosystems and organisms. In this work, a novel ratiometric fluorescent probe CMT (5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-pentene-1,3-dione) based on coumarin was developed for detecting Hg²⁺, which displayed obvious fluorescence changes, a low detection limit (2.24 × 10⁻⁷ M), good selectivity, and a large Stokes shift (255 nm). The CMT probe could detect Hg²⁺ in real environmental soil and water samples. Furthermore, the CMT probe enabled the naked-eye detection of Hg²⁺ using test paper experiments. CMT was also applied for fluorescence imaging in living zebrafish and plants. This work provides a highly efficient tool for monitoring Hg²⁺ in environmental samples and biological systems.