A fluorescence turn-on sensor for Hg ²⁺ with a simple receptor available in sulphide-rich environments

Detection of Hg ²⁺ in complex natural environmental conditions is extremely challenging, and no entirely successful methods currently exist. Here we report an easyto- prepare fluorescent sensor B3 with 2-aminophenol as Hg ²⁺ receptor, which exhibits selective fluorescence enhancement toward Hg ²⁺ over other metal ions. Especially, the fluorescence enhancement was unaffected by anions and cations existing in environment and organism. Moreover, B3 can detect Hg ²⁺ in sulphide-rich environments without cysteine, S ^2- or EDTA altering the fluorescence intensity. Consequently, B3 is capable of distinguishing between safe and toxic levels of Hg ²⁺ in more complicated natural water systems with detection limit ≤2 ppb.