Experiments were carried out for potassium salts since the cation domain that builds the investigated molecule should have shown the highest selectivity towards this cation. In Fig. , we changed the concentration of fluoride ions in the aqueous phase. The dependence between the logarithm of the anion concentration and oxidation reaction potential of 5FSQC6 is linear, and the slope of the curve is (-57 ± 3) mV per decade for the first oxidation reaction and (-101 ± 4) mV per decade for the second reaction. Both reactions result in the transfer of the anion from the aqueous phase to the organic phase. For the first redox reaction, the value is very close to the value obtained from the Nernst-like equation describing the ion transfer process. The slope of the second reaction is different but indicates a more complicated transfer mechanism as could be expected from the second oxidation with one anion already bonded to the receptor.