Construction of a Hg2+-Sensitive Fluorescent Probe Derived from Rhodamine B

A rhodamine B-based Hg2+-sensitive fluorescent probe P was characterized in H2O-EtOH solution (7:3, v:v, pH 7.0, 2 mM HEPES). Over other tested cations, only the addition of Hg2+ induced the opening of the spiral ring structure of P, and a fluorescence enhancement occurred at 595 nm with a naked eye observed color change from colorless to pink. Using Na2S as a complexing agent, the reversibility of the P-Hg2+ system was proved. The linear range of P for Hg2+ was 9.0×10-6-3.0×10-5 M with a detection limit of 3.0×10-6 M.