A new NIR-emissive fluorescence turn-on probe for Hg2+ detection with a large Stokes shift and its multiple applications

A novel fluorescence off-on Hg2+ probe with near-infrared (NIR) emission (680 nm) and a large Stokes shift (240 nm) has been developed. In MeCN/H2O (1/1, v/v, HEPES (N-2-hydroxyethylpiperazine-N-ethane-sulphonic acid) 10 mM, pH = 7.4) solution, (E)-O-(2-(benzo[d]thiazol-2-yl)-4-(2-(3-(dicyanomethylene)-5,5-dimethylc-yclohex-1-en-1-yl)vinyl)-6-methylphenyl)-O-phenyl carbonothioate (HBTD-M) can detect Hg2+ with high selectivity and sensitivity. The sensing mechanism is based on Hg2+-triggered cleavage of carbonothioate moiety in probe HBTD-M, which results in releasing of its precursor (E)-2-(3-(3-(benzo[d]thiazol-2-yl)-4-hydroxy-5-methylstyryl)-5,5-dimethylcyclohex-2-en-1-ylidene)malononitrile (HBTD). In addition, HBTD-M has been successfully used to detect Hg2+ in real water, soil, and seafood samples with good recoveries and small relative standard deviations.