A Large Stokes Shift Reaction-Based Colorimetric and Ratiometric Fluorescent Probe for Hg²⁺ Detection and its...

Based on Hg²⁺-triggered deselenation-hydrolysis self-immolative reaction, a novel colorimetric and ratiometric fluorescent probe L-1 for Hg²⁺ detection was fabricated. L-1 had maximum absorption and fluorescence emission peaks at 496 nm and 648 nm respectively. Upon reaction with Hg²⁺, these peaks underwent a marked blue shift to 386 nm and 528 nm respectively. Concurrently, the solution colors of L-1 displayed a color transition: from pink to colorless under natural light, and from red to green under a 365 nm UV lamp. Notably, L-1 enabled colorimetric and ratiometric detection of Hg²⁺ via the fluorescence intensity ratio (F_{528 nm}/F_{648 nm}), featuring a large Stokes shift (152 nm), rapid response (6 min), favorable sensitivity (LOD = 0.4 µM), and excellent selectivity against other coexisting metal ions. Furthermore, L-1 was successfully employed for detecting Hg²⁺ in real water samples, such as river water, tap water and drinking water. Most importantly, by integrating the concentration-dependent color gradient of Hg²⁺ with a smartphone application for red-green-blue (RGB) analysis, we established an instrument-free platform for rapid on-site Hg²⁺ detection.