Calix[4]pyrrole: An Old yet New Ion‐Pair Receptor

Abstract

Ditopic cation–anion binding is revealed by solid-state studies of the anion-recognition behavior of the calix[4]pyrrole unit. Anion binding causes an electron-rich conelike cavity to be formed that can then bind large polarizable cations. Furthermore, complexation of calix[4]pyrrole with cesium carbonate results in dimerization, in which a single anion bridges two calix[4]pyrroles (see the crystal structure of the Cs2CO3 complex). Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2005/z462945_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.