Generating Flexibility in Inclusion Compounds that Possess Solvent-Accessible Voids: An Alternative Route to Control Pore Size in Three-Dimensional Nanoporous Molecular Crystals

Exceptionally flexible inclusion compound having three-dimensional (3D) solvent-accessible voids was built from single 1,3-ethylene diamide bridged p-tert-butyl-calix­[4]­arene. The robustness of the crystalline order originates from a fascinating square-grid framework of open molecular capsules that is built entirely from van der Waals forces and weak hydrogen bonding. Yet, its flexibility is induced by a controlled solvent-directed “breathing behavior”. The 3D network of channels generates extrinsic voids sufficiently elastic to trap different sizes of alcohol molecules. Careful extraction of solvent from these voids produces 3D nanoporous molecular crystals with controlled pore size.