In Nature, the binding and transport of ions has a vital function in many fundamental systems. More specifically, anions have crucial roles within many biological processes, such as maintaining neutrality in charged transport processes, 1 maintaining intra-and extracellular pH, and controlling cellular volumes. A number of diseases known as channelopathies, including cystic fibrosis (CF) and Bartter syndrome, are caused by the dysregulation or inhibition of ion transport through membrane-embedded ion channels. Anion transporters offer the possibility of opening up new ways of treating diseases such as CF by replacing the function of the faulty ion channels (an approach known as a channel replacement therapy) or disturbing both ionic and pH gradients across cancer cell membranes and within cells, triggering cell death To this end, a major goal of transporter design has been the enhancement of transport activity, thereby creating more potent systems. However, recently the focus of synthetic ionophore research has shifted from gradual increases in small molecule binding and transport efficiencies to detailed investigations into the mechanism of transport. The selectivity of the transporter for binding anions over protons and the mechanism of proton transport by anionophores has been suggested to correlate with cytotoxicity. Therefore, by considering the mechanism of transport and intrinsic anion selectivity when applying transporter design principles to new transporters, there is great potential for such research to be used in therapeutic applications. This shift in the design process has been exemplified by a series of biotin [6]uril esters reported by Lisbjerg et al., which incorporated soft C-H•••X -bonding moieties and demonstrated Cl -> HCO3 -selective transport. Synthetic vesicles composed of phospholipids are often used as model cells in anion transport experiments. The modification and wide adoption of this practical and flexible technique has provided a multitude of assays to determine the activity of a transporter in a lipid bilayer. Assays that rely on an anion exchange process, such as the chloride/nitrate exchange assay or the lucigenin fluorescence quenching assay, have been widely used to analyse the anion binding and transport of synthetic transporters.