A specific and ratiometric chemosensor for Hg2+ based on triazole coupled ortho-methoxyphenylazocalix[4arene

Nae Jen Wang, Chung-Ming Sun*, Wen-Sheng Chung

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Calix[4arene 3, which contains two distal triazole groups on the lower rim and two distal o-methoxyphenylazo groups on the upper rim, was synthesized and found to be a specific and ratiometric sensor for Hg2+ in a polar protic solvent. A series of o-methoxyphenylazo derivatives (3, 4, 5, 7, and 9) were synthesized, which proved that the lower-rim triazoles and the hydroxyl azophenol(s) were the major ligands for metal ion binding. Though analogues 4 and 10 showed some sensitivity for Hg2+, compound 3 was the only ratiometric chemosensor for Hg2+ among the series of azocalix[4arenes synthesized in this work. The formation of 3·Hg2+ complex was supported by UV/vis and NMR titration studies and Mass spectrometry. Based on the symmetrical features of NMR spectra of 3·Hg2+, the complex is believed to be symmetrical with respect to the calix[4arene cavity. Furthermore, the complex was determined to be 1:1 binding stoichiometry by Job's plot, and the association constant was determined to be 4.02×10 3 M-1 using Benesi-Hildebrand plot.

Original languageEnglish
Pages (from-to)8131-8139
Number of pages9
Issue number42
StatePublished - 21 Oct 2011


  • Azocalix[4]arene
  • Chemosensor
  • Click reaction
  • Mercury ion
  • Triazole


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