Selective and sensitive turn on detection of Hg2+ in aqueous solution using a thioether-appended dipeptide

A fluorescent chemosensor (4) was synthesized by coupling two dansyl labeled amino acids with the thioether bond. Compound 4 showed exclusively selective and sensitive response toward Hg2+ among 14 tested metal ions in aqueous solution. Compound 4 exhibited 11-fold enhanced emission intensity in the presence of Hg2+ (1 equiv). The detection limit of 4 for Hg2+ in aqueous solution is 14.2 nM (2.8 ppb) and 4 showed a sensitive linear response to Hg2+ in the concentration range (0–5 × 10−7 M). The sensitive detection of Hg2+ using 4 was not interfered by other competitive metal ions such as Cd2+, Cu2+, and Ag+.