XCage: A Tricyclic Octacationic Receptor for Perylene Diimide with Picomolar Affinity in Water

Wenqi Liu, Sharan Bobbala, Charlotte L. Stern, Jessica E. Hornick, Yugang Liu, Alan E. Enciso, Evan A. Scott, J. Fraser Stoddart*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


The rational design of wholly synthetic receptors that bind active substrates with ultrahigh affinities is a challenging goal, especially in water. Here, we report the synthesis of a tricyclic octacationic cyclophane, which exhibits complementary stereoelectronic binding toward a widely used fluorescent dye, perylene diimide, with picomolar affinity in water. The ultrahigh binding affinity is sustained by a large and rigid hydrophobic binding surface, which provides a highly favorable enthalpy and a slightly positive entropy of complexation. The receptor-substrate complex shows significant improvement in optical properties, including red-shifted absorption and emission, turn-on fluorescence, and efficient energy transfer. An unusual single-excitation, dual-emission, imaging study of living cells was performed by taking advantage of a large pseudo-Stokes shift, produced by the efficient energy transfer.

Original languageEnglish (US)
Pages (from-to)3165-3173
Number of pages9
JournalJournal of the American Chemical Society
Issue number6
StatePublished - Feb 12 2020

ASJC Scopus subject areas

  • General Chemistry
  • Biochemistry
  • Catalysis
  • Colloid and Surface Chemistry


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