An artificial selective binding pocket for multivalent anions

In the study, we designed and synthesised a V-shaped quadruple amide receptor R with a pocket of multiple hydrogen-bond network and characterised it through NMR, HRMS and single crystal X-ray diffraction. By the pre-organised hydrogen-bonding interactions, its pocket could accommodate some selected anions such as CF3SO3-, HSO4-, H2PO4-, Cl- and Br-. The binding constants of R to the guest anions span the order of magnitude from the first power of ten to the third power of ten, according to the 1H NMR titration experiments. The recognition of R to the multivalent anions demonstrated high selectivity, reaching up to 258.8 between the complexes of R with H(2)PO(4)(- )and Br-. The density functional theory calculations of these stable complexes illustrated that the origin of the high selectivity is the self-fitness of the shape of R's binding pocket to the shape of guest anions. [GRAPHICS]