A novel colorimetric and off–on fluorescent sensor for Hg2+ and its application in live cell imaging

A novel rhodamine-based fluorescent probe L2 with two “S” groups was synthesized and characterized. As expected, L2 exhibited high selectivity and sensitivity for Hg2+ over other commonly coexistent metal ions. Its selectivity is excellent, and the detection limit was measured to be 1 ppm. The significant changes in the fluorescence color could be used for naked-eye detection. Furthermore, fluorescence imaging experiments of Hg2+ ions in living EC-109 cells demonstrated its value of practical applications in biological systems.