Rhodamine-Based Fluorescent Probe for Highly Selective Determination of Hg 2 .

The determination of mercuric ions (Hg 2+ ) in environmental and biological samples has attracted the attention of researchers lately. In the present work, a novel turn-on Hg 2+ fluorescent probe utilizing a rhodamine derivative had been constructed and prepared. The probe could highly sensitively and selectively sense Hg 2+ . In the presence of excessive Hg 2+ , the probe displayed about 52-fold fluorescence enhancement in 50% H 2 O/CH 3 CH 2 OH (pH, 7.24). In the meantime, the colorless solution of the probe turned pink upon adding Hg 2+ . Upon adding mercuric ions, the probe interacted with Hg 2+ and formed a 1:1 coordination complex, which had been the basis for recognizing Hg 2+ . The probe displayed reversible dual colorimetric and fluorescence sensing of Hg 2+ because rhodamine's spirolactam ring opened upon adding Hg 2+ . The analytical performances of the probe for sensing Hg 2+ were also studied. When the Hg 2+ concentration was altered in the range of 8.0 × 10 -8 to 1.0 × 10 -5 mol L -1 , the fluorescence intensity showed an excellent linear correlation with Hg 2+ concentration. A detection limit of 3.0 × 10 -8 mol L -1 had been achieved. Moreover, Hg 2+ in the water environment and A549 cells could be successfully sensed by the proposed probe.