A crystalline sponge based on dispersive forces suitable for X-ray structure determination of included molecular guests

摘要

A crystalline porous material showing one-dimensional (1-D) rectangular micropores (12 x 9 angstrom(2)) has been assembled from a semirigid macrocyclic tetraimine and EtOAc as the templating agent. The 1-D nature of the material is intrinsic to the conformationally rigid structure of a macrocyclic sub-unit bearing four cyclohexylidene residues. The multiple dispersive forces established among the aliphatic residues glutted the 1-D channels and provided thermal stability to the material at temperatures below 160 degrees C. Upon removal of the template, the structure of the empty solid exhibited permanent microporosity (S-BET = 342 m(2) g(-1)). Being a true molecular sponge, the channel framework of this material allowed the inclusion of a variety of molecular sample guests without compromising its crystalline nature. Remarkably, this crystalline material enabled the structure determination by X-ray diffraction of the included molecules. Theoretical studies demonstrated the vital role played by the dispersive forces in the overall stabilization of the crystal packing.