Sulfate uniport by 1 was not observed even at 0.1 mol% concentration of 1 in either Na + or NMDGH + sulfate solutions (Figure ). However, slow but clear Cl -/SO4 2-antiport by 1 was observed using the lucigenin assay. The ability of 1 to transport SO4 2-in this case may be driven by the Cl -transport, resulting in the creation of a charge gradient across the membrane. The transport of highly hydrated SO4 2-is not easy, and it is generally assumed, that it cannot be transported. Only a few urea-based transporters have been reported to be able to transport this anion.