semiaza-Bambus[6]urils efficiently transport anions across lipid membranes. A systematic modification of their lipophilic side chains to include various alkyl groups and thioethers reveals that the most efficient chloride transporters are those that agree with Lipinski's rule-of-lipophilicity, exhibiting clog P_o/w values close to 5. Furthermore, vesicle anion-transport assays show that the new anion-transporters are independent of the cation identity but exhibit high anion selectivity, NO₃⁻ > Br⁻ > Cl⁻ > SO₄²⁻, in agreement with the Hofmeister series. These findings will allow for the design of highly specific anion transporters for biomedical applications, particularly for managing anion channelopathies.