Selective and Sensitive Detection of Hg²⁺ and Ag⁺ by a Fluorescent and Colorimetric Probe with Large Stokes Shift

Development of fluorescent sensors with large Stokes shift for selective detection of heavy metals is of great importance. A novel fluorescent probe with extremely large Stokes shift (212 nm) was synthesized for selective and simultaneous detection of Hg²⁺ and Ag⁺ ions. The deep yellow probe turned colorless or pale yellow after addition of Hg²⁺ or Ag⁺. The new probe could be utilized for absorption spectral detection of Hg²⁺ and Ag⁺ both in ethanol and aqueous solution. Addition of Hg²⁺ and Ag⁺ ions caused significant decrease in the fluorescence intensity of the new probe and the selective recognition of Hg²⁺ and Ag⁺ was not interfered by common competitive metal ions including Li⁺, Na⁺, K⁺, Cu²⁺, Fe²⁺, Zn²⁺, Co²⁺, Ni²⁺, Mn²⁺, Sr²⁺, Ca²⁺, Mg²⁺, Al³⁺, Cr³⁺ and Fe³⁺. The detection limit for Hg²⁺ and Ag⁺ was calculated to be 4.68 μM and 4.29 μM, respectively. Application of the new probe for quantitative determination of Hg²⁺ and Ag⁺ concentrations in real water samples was accomplished.