Novel bile acid-based cyclic bisimidazolium receptors for anion recognition

Novel deoxycholic acid-based cyclic receptors, 3 and 4, containing two imidazolium groups and m-xylene and p-xylene as spacers have been synthesized. These receptors bind anions through hydrogen bonds utilizing two imidazolium (C-H)(+) and inwardly directed methylene hydrogens of both acetyl groups. Receptor 3 shows a moderate selectivity for fluoride ion whereas receptor 4 shows high affinity and selectivity for chloride ion in CDCl3.