In this work, the anion transport activity of eleven fluorinated BU derivatives and a non-fluorinated analogue across phospholipid bilayers is presented (Figure ). BUs 1 and 7 have previously been reported as highly active Cl -/HCO3 -transporters. Here we compare the rates of Cl -/HCO3 -transport by all twelve BUs, showing how slight variations in the substituents impact the transport activity of the fluorinated BUs. Furthermore, we present the impact of changes in the lipid composition as well as a comparison of the transport of different anions.