Hg(II)-Mediated Intramolecular Cyclization Reaction in Aqueous Media and Its Application as Hg(II) Selective Indicator

The Hg(II)-specific intramolecular cyclization reaction of ethynyl phenols was carried out for the first time in semiaqueous media at ambient temperature. The reaction unit (ethynyl phenol) was coupled with a malononitrile derivative (signal unit), which afforded the chromogenic Hg(II) indicator 7. The reaction of the chromogenic Hg(II) indicator 7 was further optimized in DMSO/water (3:7, v/v) (10 mM PBS buffer, pH = 7.0). Compound 7 displays a color change from blue to pale yellow in the presence of Hg(II).