Anions play an important role in the field of supramolecular
chemistry. Anions are mainly recognized through hydrogen-bond-
ing interactions, 1 electrostatic interactions, 2 and coordination
through metal ions 3 . Among various non-covalent interactions,
hydrogen-bonding interactions are particularly useful and effective
in this regard. Receptors bearing functional groups such as
amides, 4 ureas, 5 thioureas, 6 imidazolium, 7 and positively charged
groups 8 have been widely used to recognize anions via hydro-
gen-bonding interactions