Very Strong Binding for a Neutral Calix[4]pyrrole Receptor Displaying Positive Allosteric Binding

Troels Duedal, Kent A. Nielsen, Gunnar Olsen, Charlotte B.G. Rasmussen, Jacob Kongsted, Eric Levillain, Tony Breton, Eigo Miyazaki, Kazuo Takimiya, Steffen Bähring, Jan O. Jeppesen

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


The dual-analyte responsive behavior of tetraTTF-calix[4]pyrrole receptor 1 has been shown to complex electron-deficient planar guests in a 2:1 fashion by adopting a so-called 1,3-alternate conformation. However, stronger 1:1 complexes have been demonstrated with tetraalkylammonium halide salts that defer receptor 1 to its cone conformation. Herein, we report the complexation of an electron-deficient planar guest, 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA, 2) that champions the complexation with 1, resulting in a high association constant Ka = 3 × 1010 M-2. The tetrathiafulvalene (TTF) subunits in the tetraTTF-calix[4]pyrrole receptor 1 present a near perfect shape and electronic complementarity to the NTCDA guest, which was confirmed by X-ray crystal structure analysis, DFT calculations, and electron density surface mapping. Moreover, the complexation of these species results in the formation of a charge transfer complex (22⊂1) as visualized by a readily apparent color change from yellow to brown.

Original languageEnglish
Pages (from-to)2123-2128
Number of pages6
JournalJournal of Organic Chemistry
Issue number4
Publication statusPublished - 2017 Feb 17
Externally publishedYes

ASJC Scopus subject areas

  • Organic Chemistry


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