Anion receptor with xylene bridged two imidazolium rings

A m-xylene bridged imidazolium receptor I has been designed and synthesized. The receptor 1 utilizes two imidazole (C-H)(+)-anion hydrogen bonds and one aromatic hydrogen-anion hydrogen bond. The major driving force of complexation between the receptor 1 and anions comes from two imidazole (C-H)(+)-anion hydrogen bonding. However, some hydrogen bonding energy between aromatic hydrogen and anion exists, although it is expected to be much smaller than that of imidazole (C-H)(+)-anion hydrogen bonds.