Previously we have reported rather low activities for Cl -and NO3 -uniport by 1 when the proton channel gramicidin was used for proton transport. However, we found much higher Cl -uniport rates when employing carbonyl cyanide m-chlorophenyl hydrazone (CCCP) as a protonophore. Indeed, 1 exhibited a high activity as a uniporter of both Cl -and NO3 -, even at low concentrations (0.002 mol%, Figures and). An intriguing difference was observed when Cl -uniport by 1 was tested using the HPTS assay in NaCl instead of NMDG H + Cl -solution. In NaCl, the Cl -uniport by 1 was found to be considerably slower than in NMDGH + Cl -solution (Figure ), suggesting that cations might have an impact on the anion transport properties of BUs. However, it is the question whether they are directly involved in the transport process or if they might impact anion exchange at the membrane periphery by BUs. This phenomenon is a subject of future investigations.