An Anthracene-Based Hg²⁺ Fluorescent Probe with Dithioacetal: Simple Synthesis, High Selectivity and Sensitivity, and Dual-Mode Detection Capability

With the development of the chemical industry, the threat of mercury pollution to human health is increasing. Therefore, it is necessary to develop a low-cost, convenient and efficient Hg²⁺ detection method. In this study, anthracene-based Hg²⁺ fluorescent probes AN-2S and AN-4S were synthesized by a dithioacetal reaction for the rapid and efficient detection of the Hg²⁺ concentration in water. Through molecular structure design and synthesis route optimization, the complexity and cost of the probe synthesis were greatly reduced. AN-2S and AN-4S had good water solubility, rapid response abilities and anti-interference abilities, and could specifically detect Hg²⁺ using “turn-off” or “turn-on” detection modes within 1 min. The AN-4S probe showed a wide linear response range (0~40 μmol/L) and high sensitivity (4.93 × 10⁻⁸ mol/L) to Hg²⁺ in 99% aqueous solutions, over a pH range of 5~13. The reaction mechanism between the probe and Hg²⁺ was determined using 1H NMR and FT-IR spectra and Job’s curves. It was proven that the AN-2S and AN-4S probes react with Hg²⁺ in a molar ratio of 1:1 or 1:2. The dual-detection mode enabled the probes to be used not only for the accurate quantitative detection of Hg²⁺ under a fluorescence spectrometer, but also for rapid qualitative analysis using a UV flashlight as a test strip, showing a broad practical application potential.