Fluorous bulk membranes for potentiometric sensors with wide selectivity ranges: Observation of exceptionally strong ion pair formation

Potentiometric sensors based on fluorous membranes doped with a fluorophilic tetraphenylborate derivative are shown to have a remarkably wide range of selectivities that exceeds the selectivity range of conventional polymeric membranes by 8 orders of magnitude. The fluorous character of these sensing membranes explains the formation of ion pairs of unprecedented strength. Ion pair formation constants in perfluoroperhydrophenanthrene, as measured in this work, are on the order of 10²⁰ and exceed previously reported values for ion pair formation in nonpolar solvents by 6 orders of magnitude. The low solubility of lipids in such fluorous phases makes them very promising for the reduction of biofouling.