Cation-coordinating properties of perfluoro-15-crown-5

While the stabilities of perfluorocrown ether complexes with cations have been known to be weak at most, no quantitative data have been available to confirm complexation. This contribution uses 19F NMR spectroscopy and ion-selective potentiometry to show that perfluoro-15-crown-5 indeed binds weakly to Na+ and K+ but not to H+, Li+, and NH4+.