A self-assembled framework that interpenetrates in crystal but does not interpenetrate in solution

A porous supramolecular framework has been for the first time revealed to undergo interpenetration in crystal and non-interpenetration in solution. A new supramolecular organic framework Bu-SOF has been constructed from the co-assembly of a tetracationic tetrahedral monomer and cucurbit[8]uril (CB[8]) in water through the encapsulation of two anti-parallel n-butyl chains by CB[8]. X-ray diffraction analysis reveals that Bu-SOF forms 3-fold interpenetrated networks in crystals grown by evaporation of its solution in water. H-1 NMR, dynamic light scattering and isothermal titration calorimetric experiments confirm that Bu-SOF is also formed in water. Solid samples, prepared by lyophilizing the aqueous solution of Bu-SOF, can adsorb nanoscaled organic dyes, supporting the porosity of the framework and thus non-interpenetration in solution. The avoidance of interpenetration of Bu-SOF in solution has been attributed to the filling of water inside the porous framework as well as the electrostatic repulsion of the appended bipyridinium units of the tetrahedral building block.

Automated summary

A new porous supramolecular framework, Bu-SOF, has been discovered to exhibit interpenetration in crystals and non-interpenetration in solution. This phenomenon is attributed to the presence of water filling inside the porous framework and the electrostatic repulsion between the appended bipyridinium units of the tetrahedral building block.