Carbazole sulfonamide-based macrocyclic receptors capable of selective complexation of fluoride ion

Two carbazole sulfonamide-based macrocycles 1 and 2 were facilely synthesized and carefully evaluated for their anion recognition properties. The obtained results revealed that macrocycle 1 with a 1,3-xylyl linker was able to bind fluoride ion more strongly and selectively in acetonitrile medium than its strong competitors (like acetate and dihydrogen phosphate anions), with a large binding constant (K-a) of 50 878 M-1. More importantly, an exclusive fluoride recognition was achieved for macrocycle 1 in the more polar DMSO-d(6) solution, albeit with a moderate affinity of K-a = 147 M-1. Compared with macrocycle 1, macrocycle 2 bearing a 2,6-lutidinyl linkage exhibited a remarkable change not only in the anion affinity but also in the anion selectivity, although with only a slight difference in their molecular structures.

Automated summary

Two carbazole sulfonamide-based macrocycles were synthesized and evaluated for their anion recognition properties, with macrocycle 1 showing stronger and more selective binding towards fluoride ion compared to its competitors. Macrocycle 2 exhibited significant changes in anion affinity and selectivity despite only slight differences in molecular structures.