Repositioning Chloride Transmembrane Transporters: Transport of Organic Ion Pairs.

Given the biological importance of organic cations, the facilitated transport of organic ion pairs could find many applications. Calix[6]arene tris(thio)ureas, which possess a cavity that can accommodate primary ammonium ions, can not only act as carriers for Cl /NO antiport but can also perform the cotransport of PrNH Cl. Transport was monitored by fluorescence spectroscopy and the presence of the different species inside the vesicles was characterized by H and Cl NMR experiments involving shift reagents.