PNNL

Abstract

The unprecedented tetrahedral anion-? receptors have been successfully constructed by a macrocycle-directed approach. The use of large macrocycle precursors bearing four reaction sites enabled kinetic-favored cross-linking pathway and afforded otherwise-inaccessible tetrahedral cages in considerable yields. Crystal structure suggested that the tetrahedral cages have an enclosed three-dimensional cavity surrounded by four electron-deficient triazine faces in a tetrahedral array. The complementary accommodation of a series of tetrahedral and relevant anions including BF4-, ClO4-, H2PO4-, HSO4-, SO42- and PF6- has been observed by ESI-MS. Two complex crystal structures with ClO4- and PF6- demonstrated the anion was nicely encapsulated within the tetrahedral cavity through up to quadruple cooperative anion-? interactions by an excellent shape and size match. The favored complexation energies were established by DFT calculation and further confirmed by negative ion photoelectron spectroscopy study.