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.