10.1021/ja310673p.s002 Sung Kuk Kim Sung Kuk Kim Vincent M. Lynch Vincent M. Lynch Neil J. Young Neil J. Young Benjamin P. Hay Benjamin P. Hay Chang-Hee Lee Chang-Hee Lee Jong Seung Kim Jong Seung Kim Bruce A. Moyer Bruce A. Moyer Jonathan L. Sessler Jonathan L. Sessler KF and CsF Recognition and Extraction by a Calix[4]crown‑5 Strapped Calix[4]pyrrole Multitopic Receptor American Chemical Society 2016 system 1 acts anion receptor 1 mode calix CsF 1 H NMR spectroscopic analyses 3OD KF cation 2016-02-20 03:06:14 Dataset https://acs.figshare.com/articles/dataset/KF_and_CsF_Recognition_and_Extraction_by_a_Calix_4_crown_5_Strapped_Calix_4_pyrrole_Multitopic_Receptor/2457478 On the basis of <sup>1</sup>H NMR spectroscopic analyses and single crystal X-ray crystal structural data, the ion-pair receptor <b>1</b>, bearing a calix[4]­pyrrole for anion binding and calix[4]­arene crown-5 for cation recognition, was found to act as a receptor for both CsF and KF ion-pairs. Both substrates are bound strongly but via different binding modes and with different complexation dynamics. Specifically, exposure to KF in 10% CD<sub>3</sub>OD in CDCl<sub>3</sub> leads first to complexation of the K<sup>+</sup> cation by the calix[4]­arene crown-5 moiety. As the relative concentration of KF increases, then the calix[4]­pyrrole subunit binds the F<sup>–</sup> anion. Once bound, the K<sup>+</sup> cation and the F<sup>–</sup> anion give rise to a stable 1:1 ion-pair complex that generally precipitates from solution. In contrast to what is seen with KF, the CsF ion-pair interacts with receptor <b>1</b> in two different modes in 10% CD<sub>3</sub>OD in CDCl<sub>3</sub>. In the first of these, the Cs<sup>+</sup> cation interacts with the calix[4]­arene crown-5 ring weakly. In the second interaction mode, which is thermodynamically more stable, the Cs<sup>+</sup> cation and the counteranion, F<sup>–</sup>, are simultaneously bound to the receptor framework. Further proof that system <b>1</b> acts as a viable ion-pair receptor came from the finding that receptor <b>1</b> could extract KF from an aqueous phase into nitrobenzene, overcoming the high hydration energies of the K<sup>+</sup> and F<sup>–</sup> ions. It was more effective in this regard than a 1:1 mixture of the constituent cation and anion receptors (<b>4</b> and <b>5</b>).