A squaraine based fluorescent probe for mercury ion via coordination induced deaggregation signaling

Due to the high affinity between dithiocarbamate (DTC) and Hg2+, a fluorescent probe based on squaraine chromophore with DTC side arm for Hg2+via coordination induced deaggregation signaling has been designed and synthesized. Squaraine has a high tendency to aggregate in aqueous solution, and such self-aggregation usually results in a dramatic absorption spectral broadening with fluorescence emission quenching. The combination of the DTC side arm of the probe with Hg2+ induces steric hindrance, leading to the deaggregation of the dye complex, companying with a fluorescence emission restoration. In EtOH–H2O (20:80, v/v) solution, this “turn on” fluorescent probe has high selectivity and sensitivity toward Hg2+ over other metal ions, and the limit of detection for Hg2+ was estimated as 2.19 × 10−8 mol/L by 3σ/k.

Graphical abstractA squaraine based “turn on” fluorescent probe with a dithiocarbamate ionophore for mercury ion was described, and the sensing mechanism was based on coordination induced deaggregation.Figure optionsDownload full-size imageDownload as PowerPoint slide