Cation-chloride cotransport mediated by an ion pair transporter

Ion transport mediated by an ion pair receptor 1 bearing both cation and anion binding sites is presented. The ion pair binding property was revealed by means of ¹H NMR titrations in organic solutions and X-ray analysis in the solid state. Single crystal structures demonstrated that 1 and CaI₂ formed a solvent-separated ion-pair complex with two iodides each interacting with a triazine ring through anion–π interactions, whereas the calcium ion is bound by a pentaethylene glycol moiety. The ion transport activity was studied by monitoring the efflux of ions from salt-loaded EYPC large unilamellar vesicles (EYPC-LUVs) using ion selective electrodes. Chloride transport across the membrane mediated by the ion pair receptor through K⁺/Cl⁻ or Na⁺/Cl⁻ cotransport with a selectivity towards the K⁺/Cl⁻ symport was realized.