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 as2.19 ? 10à8mol/L by 3s/k. Due to the high affinity between dithiocarbamate (DTC) and Hg2 +, a fluorescent probe based on squaraine chromophore with DTC side arm for Hg2 + via induced induced gap 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. 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. This probe is highly selective and sensitive toward Hg2 + over other metal ions, and the limit of detection for Hg2 + was estimated as 2.19 (20:80, v / v) ? 10? 8mol / L by 3s / k.