A fluorescence turn-on probe based on rhodamine derivative and its functionalized silica material for Hg2+-selective detection

In current study, a novel optical probe based on rhodamine-terephthalaldehyde Schiff base was developed for exclusive detection of Hg2+ in 9:1 (v/v) ethanol/water solution, which exhibited obvious turn-on fluorescence emission when encountering Hg2+, and distinct color change from colorless to violet also enabled “naked eye” detection due to spirolactam opening of this rhodamine sensing molecule. Other common ions including alkali ions (Na+, K+) and alkaline earth metal ions(Ca2+, Mg2+) together with some transition metal ions (Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Ag+, Pb2+, Cr3+, Fe3+) could only induce negligible spectral changes. Furthermore, our probe was successfully grafted onto the surface of silica nanoparticles to guarantee sensing repeatability and explore its further applications in optical sensing devices. It turned out that, the inorganic-organic hybrid materials also exhibited excellent recognition ability to Hg2+.