Structurally Forced Ion Binding Affinity: Tetraurea‐Based Macrocycle as a Receptor for Ion Pairs

A urea‐based complexation site represents a building block customarily used in the design of receptors for anion recognition. Here we report a cyclization driven change of complexation preferences, leading to a urea‐based macrocyclic receptor with selectivity for heavier alkali metal cations. Moreover, thorough 1H and 19F NMR, HRMS and X‐ray diffraction studies of the complexes revealed an inherent capability of the macrocycle to interact with selected ion pairs.