A 2,6-diamidopyridine-based macrocyclic aromatic amide receptor with cascade ion pair recognition

Ion-pair receptors constitute an important class of synthetic receptors within the realm of host-guest and supramolecular chemistry. Their unique ability to simultaneously recognize and accommodate both cations and anions has rendered them invaluable across various applications. In this study, we have synthesized a cascade macrocyclic ion-pair receptor, composed of three 2,6-amidopyridine building blocks bridged by aromatic spacers. Notably, the diamide binding sites of this receptor exhibit a high degree of selectivity for fluoride ions. Furthermore, despite lacking any dedicated cation-binding sites within its macrocyclic structure, this receptor is capable of selectively binding tetraethylammonium cations through a series of cascade electrostatic interactions facilitated by the bound flouride ions.