Carbazole-disulfonamide-containing macrocycles as powerful anion receptors with tunable selectivity

The design of synthetic anion receptors with potent anion binding and customizable anion selectivity under competitive solvent conditions remains challenging. Herein, we report easily-synthesized 1,8-disulfonamidocarbazole- and 3,5-diamidopyridine-based hybrid macrocycles 1-3 and reveal their strong anion recognition properties as determined by ¹H NMR/UV-vis titration studies, X-ray diffraction measurements, and DFT calculations. While the dithioamidopyridine-based macrocycle 2 displayed strong and selective binding of AcO^- in DMSO, modification of the selectivity pattern towards the more basic F^- anion was achieved by replacing the thioamides moieties to amides (macrocycle 1). For macrocycle 3 (bearing pyridine N-oxide core), no selectivity was observed among F^-, AcO^-, and H₂PO₄^- ions. The demonstration of tunable anion selectivity by slight structural modifications in our macrocycles is informative for developing structurally simple anion receptors with the desired selectivity for transmembrane anion transport, anion sensing, and anion sequestration applications.