Selective and sensitive ratiometric detection of Hg ²⁺ in 100% aqueous solution with triazole-based dansyl probe

An amino acid-based fluorescent sensor (3) bearing a triazole group was synthesized by solid phase synthesis using click chemistry. 3 showed highly sensitive ratiometric response to Hg ²⁺ in 100% aqueous solution. The dissociation constant for Hg ²⁺ in aqueous solution was calculated to be 672 nM. 3 exhibited selective response to Hg ²⁺ among 13 tested metal ions and the sensitive detection of Hg ²⁺ by 3 was not interfered by other heavy metal ions, Group I and II metal ions. ¹H NMR analysis revealed that two sulfonamide and triazole groups of 3 played a critical role in the interactions with Hg ²⁺. 3 penetrated live cells and detected intracellular Hg ²⁺. 3 allowed selective and sensitive ratiometric detection of Hg ²⁺ in live cells as well as in 100% aqueous solution.