Cholapod and Cholaphanes for Recognition of Anions

Deoxycholic and cholic acid-based receptors 6, 13, and 16 containing imidazolium groups were synthesized, and their properties as anion receptors have been evaluated. Cholaphanes 13 and 16 exhibited moderate binding selectivity and affinity for fluoride ions, while cholapod 6 showed low binding selectivity and affinity for chloride ions due to the presence of a nitro group in the imidazolium ring. The H-bonding interactions involve C-2 protons of imidazolium ring with anion. The detection of halide ions is revealed by the binding constant through the 1H NMR titration experiment.