A highly sensitive and selective optical probe for detection of Hg2+ based on a 2,5-bis[2-(benzylthio)aniline]-croconaine

A highly sensitive and selective optical probe , 2,5-bis[2-(benzylthio)aniline]-croconaine ( BAC ) for sensing of Hg 2+ was synthesized. The BAC can efficaciously recognize Hg 2+ with the existence of competing cations (Ba 2+ , Fe 3+ , Na + , Ca 2+ , Co 2+ , K + , Mg 2+ , Ni 2+ , Cu 2+ , Pb 2+ , Al 3+ , Pb 2+ , Cr 3+ , Cd 2+ , Ag + ) in DMSO . The binding constant (Ka) of BAC -Hg 2+ was calculated to be about 1.6 × 10 5  M −1 . Simultaneously, the chelating mode of BAC -Hg 2+ was confirmed by Job’s plot, FT-IR and 1 H NMR. “Naked eye” detection has been performed, indicating the potential application of BAC on conveniently, selectively and fast detection of Hg 2+ . Moreover, Hg 2+ and EDTA could be employed as inputs and the fluorescence emission intensity which was 480 nm as output so that a molecular logic gate could be realized.