1,3-alternate calix[4]arene as a homobinuclear ditopic fluorescent chemosensor for Ag+ ions

I. Ting Ho, Kuan Chang Haung, Wen-Sheng Chung*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

A novel 1,3-alternate calix-[4]arene L, containing two different cationic binding sites of bis-triazoles and bis-enaminone groups, was synthesized and shown to be a homobinuclear ditopic fluorescent chemosensor for Ag+ ions. The fluorescence intensity of L was selectively enhanced by binding with Ag+ ions in methanol/chloroform (49:1, v/v) cosolvent. In the presence of most competing metal ions, L retains its selectivity toward Ag + ion. The binding constants K1 and K2 of the successive complexation of L with the first and second Ag+ ions were calculated to be 4.46×103 and 9.20×104M -1, respectively. The higher K2 value revealed that a positive allosteric effect participated in the complexation of L with the second equivalent of Ag+. Based on 1HNMR titration results, we inferred that the two distal bis-enaminone and bis-triazole groups on L cooperatively coordinated to Ag+ ions with the help of cation-π interactions from the phenoxy rings. Furthermore, the ESI-MS spectrometry clearly proved the formation of the homobinuclear complex L·(Ag +)2, because a base peak at m/z of 750.1701 was detected and its isotope pattern was in excellent agreement with the calculated one.

Original languageEnglish
Pages (from-to)2738-2746
Number of pages9
JournalChemistry - An Asian Journal
Volume6
Issue number10
DOIs
StatePublished - 4 Oct 2011

Keywords

  • calixarenes
  • click chemistry
  • cycloaddition
  • fluorescence probes
  • receptors

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