A highly selective colorimetric and long-wavelength fluorescent probe for Hg2+

A simple cell-permeable long-wavelength fluorophore 1-(3-cyano-2-dicyanomethylen-5,5-dimethyl-2,5-dihydrofuran-4-yl)-2-(4-hydroxylphenyl)ethane (2) was designed and synthesized. Based on this novel fluorophore, probe 1 employing a vinyl group as a recognition receptor was synthesized to highly selective detect Hg2+ in the presence of other metal ions. Probe 1 could quantificationally detect Hg2+ by the absorption and fluorescence spectroscopy methods with excellent sensitivity. Additionally, our proposed probe exhibited a large (162 nm) red-shifted absorption spectrum and the color changes from yellow to blue upon addition of Hg2+. The reaction mechanism of probe 1 and Hg2+ was confirmed using 1H-NMR, 13C-NMR, and ESI-MS. Practical application and cell imaging of probe 1 further demonstrated that it provided an excellent method for the determination of Hg2+ in the environment and living systems.