A coumarin-based fluorescent PET sensor utilizing supramolecular pK a shifts

Na'Il Saleh, Yaseen A. Al-Soud, Leena Al-Kaabi, Indrajit Ghosh, Werner M. Nau

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


A new coumarin derivative containing benzothiazole and piperazine substituents was synthesized. Preferential inclusion of the benzothiazole group, over the coumarin and piperazine groups, inside the cavity of the molecular container cucurbit[7]uril (CB7) was evidenced by using optical and NMR techniques. The binding constant of the new complex with CB7 is higher in its protonated forms (e.g., K = 2.8 × 106 M-1) than in its neutral forms, which led to an increase in the pKa value associated with protonation of the aza nitrogen on the benzothiazole ring of ca. 2.5 units. Such CB7-induced protonation disabled the photoinduced electron transfer (PET) in the included molecule, enhancing its coumarin fluorescence up to ca. 45-fold (pH 3.5, 410 nm). The results are discussed in the context of designing sensitive analytical tools for reversible monitoring of optically inactive analytes by competitive displacement experiments.

Original languageEnglish
Pages (from-to)5249-5254
Number of pages6
JournalTetrahedron Letters
Issue number41
Publication statusPublished - Oct 12 2011


  • Benzothiazole
  • Coumarin
  • Cucurbiturils
  • Fluorescence
  • Host-guest systems
  • Photoinduced electron transfer (PET)
  • Piperazine
  • Sensors
  • pK Shifts

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry


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