Facilitated transport of salts by neutral anion carriers

Partitioning of ions from water to the membrane solvent (NPOE) can be quant ified by Gibbs free energies of transfer, Delta G(tr.NPOE)(ion). These were derived from transport studies of lipophilic salts through supported liqui d membranes (SLMs) in the absence of the carrier. Partition coefficients K- p for various salts can now be calculated. The neutral anion receptors uran yl sal(oph)enes 1-5 transport Cl and H2PO4 as tetrapropylammonium salts, Th e transport is diffusion-limited and can be described by two transport para meters D-m and K-ex. From the extraction constants K-ex and the partition c oefficients K-p of the transported salts, the association constants K-a of the anion receptors for Cl and H2PO4- in NPOE were determined. Competitive transport with carriers 3 and 4 of NPr4H2PO4 and NPr4Cl demonstrated highly selective transport of H2PO4- even in the presence of excess of Cl-.