Abstract: In order to well-directed fluorescence recognize and detect Hg²⁺, according to the coordination characteristics of Hg²⁺, a novel fluorescent probe (E)-N-(4-methyl-2-oxo-1,2-dihydroquinolin-7-yl)-3-(3-phenyl-[1,2,4]triazolo[3,4-b] [1,3,4]thiadiazol-6-yl)acrylamide(MNT) was designed and synthesized, which quinolinone block was used as fluorophore. The results showed that MNT could coordinate with Hg²⁺ after the isomerization of amide bond, therefore the fluorescence quenching was generated. 1,2,4-Triazole[3,4-b]-1,3,4-thiadiazole had the characteristic of lacking electrons, which could improve the quenching effect and coordinate with Hg²⁺. The probe MNT had higher selectivity, higher quantum yield and stronger anti-interference for Hg²⁺. The detection limit was 6.35×10^-8 mol/L, the response time was 25 s. The research also found that MNT could determine Hg²⁺ in the range of pH 4-13. The fluorescence detection mechanism was speculated through nuclear magnetic titration experiments and the coordination ratio 2:1 was determined by Job's curve. The results of the application in practical water samples indicated that MNT could be used as a fluorescent probe for Hg²⁺.

Key words: Quinolinone, 1,2,4-Triazole[3,4-b]-1,3,4-thiadiazole, Fluorescence recognition, Hg²⁺