Anion Binding and Transport: Chloride binding affinities were determined by 1 H NMR binding titrations with tetrabutylammonium (TBA) chloride in d6-acetone, by monitoring the bindinginduced changes in chemical shifts of protons in the benzene ring between the two triazoles. The data in each case could be fitted to a 1:1 stoichiometric binding isotherm using Bindfit. Transporters 2 and 4, containing shorter pentyl spacers, exhibited Cl -binding constants of 153 and 130 M -1 respectively (Table ), while 3 and 5, possessing the longer hexyl spacers, showed enhanced binding (K = 897 and 720 M -1 , respectively). Moreover, as expected, replacing the nitro group with the less electron withdrawing methyl ester moiety in 6 significantly decreased the chloride binding affinity compared to 4.