Design of steroid-based imidazolium receptors for fluoride ion recognition

New deoxycholic acid-based cyclic receptors bearing imidazolium and benzimidazolium moieties bridged with o-xylelene and 1,8-dimethylenenaphthalene groups have been synthesized. Anion binding studies using 1H NMR revealed that receptors having naphthalenic group as spacer exhibit very high selectivity for fluoride ion over other anions while receptors with o-xylelene group show a preference for the chloride ion.