A dihydroxanthene-based ratiometric fluorescent probe for ultrasensitive and rapid detection of Hg2+ and its applications

Mercury ions (Hg²⁺) are highly hazardous environmental water pollutants that pose significant risks to human health and can cause severe illnesses, making their careful detection essential. Herein, we report a novel dihydroxanthene-based fluorescent probe (E)-4-(1,3-dithiolan-2-yl)-7-styryl-2,3-dihydro-1H-xanthene (SDHX-DT) for Hg²⁺ detection. When exposed to aqueous Hg²⁺, SDHX-DT undergoes a rapid desulfurization reaction, leading to a ratiometric fluorescence shift and a distinct visible color transformation from blue to green. The recognition mechanism has been fully confirmed through UV-vis, fluorescence spectroscopy, ¹H NMR, and HRMS analysis. SDHX-DT demonstrates outstanding sensing performance, featuring exceptional selectivity for Hg²⁺, strong anti-interference capability, a fast response time (< 3 min), a large Stokes shift (162 nm), and ultra-sensitivity with a detection limit of 0.62 nM. Moreover, the probe's excellent properties enable diverse practical applications, such as the convenient and portable detection of Hg²⁺ using test strips, reliable monitoring in real environmental water samples, and high-contrast fluorescence imaging in living cells.