A colorimetric and turn-on fluorescent chemosensor for selectively sensing Hg2+ and its resultant complex for fast detection of I- over S2-

A novel bipyridine-functionalized turn-on fluorescent chemosensor was successfully synthesized and fully characterized by H-1 NMR, C-13 NMR and MS, UV-vis and fluorescence spectroscopies. The sensor specifically binds to Hg2+ over other competing ions with a significant fluorescence enhancement as well as a visual colour change under physiological conditions. The detection limit of Hg2+ was as low as 32 nM, confirming very high sensitivity toward Hg2+. Moreover, the fluorescence intensity and colour change of the sensor-Hg2+ was quenched by I- or S2- and was proportional to their concentrations with a detection limit of 0.37 mu M and 0.43 mu M, respectively. The reaction of I- grabbing Hg2+ from the sensor-Hg2+ finished in 10 s due to a stronger binding force, much faster than that of S2-, which allowed fast detection of I- over S2- even in a competent environment. In addition, the sensor was successfully used for the highly sensitive detection of Hg2+ in living cells. (C) 2016 Elsevier Ltd. All rights reserved.