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>).