An anion receptor that facilitates transmembrane proton-anion symport by deprotonating its sulfonamide N-H protonElectronic supplementary information (ESI) available: Experimental procedures, X-ray crystal data, supplemental data, and the 1H- and 13C NMR spectra. CCDC 1835297, 1838526 and 1840631. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8cc04044c

Indole-based amide-sulfonamide derivatives were synthesized. The X-ray crystal structure and chloride binding studies in solution showed a 1 : 1 stoichiometry. The ion transport efficiency directly correlated to the p K a of the sulfonamide N-H protons. The mechanistic study indicated proton-anion symport across the lipid bilayer membrane. Indole-based amide-sulfonamide derivatives were synthesized. The X-ray crystal structure and chloride binding studies in solution showed a 1 : 1 stoichiometry. The ion transport study indicated the proton-anion symport across the lipid bilayer membrane.