Construction of Fluorescent Probe System Based on Click-Declick Chemical Reaction for Hg2+ Detection

Based on the click chemical reaction between hybrid rhodamine and thiol compounds and the declick chemical reaction caused by the coordinative interaction between thiol compounds and mercury ions, a ternary system of coumarin hybrid rhodamine probe, 1,3,5-benzenetrithiol and Hg2+ for fluorescence detection of Hg2+ was constructed. In this system, the probe underwent an addition reaction with the thiol group in 1,3,5-benzenetrithiol, destroying the conjugate structure of the probe and thus resulting in quenching of its red fluorescence. Hg2+ could remove 1,3,5-benzenetrithiol from the probe’s structure by coordinative binding to the compound, so the conjugate structure and red fluorescence of the probe were restored. The fluorescence intensity of the probe had a good linear relationship with the concentration of Hg2+ in the range of 5 × 10-9-1 × 10-8 and 1 × 10-8–1.1 × 10-7 mol/L, and the detection limit was 2 × 10-9 mol/L. Common heavy metal ions had no significant interference on the specific recognition of Hg2+. The recoveries of Hg2+ from spiked drinking water samples ranged from 86.7% to 110.2%.