Mechanically Interlocked Molecule-Based Porous Crystal and Its Mechanical Properties

What mechanical properties can be expected for materials composed of interlocked backbones has been a long-standing issue in materials science since the first reports on polycatenane and polyrotaxane in the 1970s. We successfully synthesized a three-dimensional porous metal–organic crystal composed of a[2]catenane. This porous crystal dynamically changes its geometry upon guest molecule release, uptake and exchange, and also upon temperature variation even in a low temperature range. We indented the crystal and obtained the Young’s moduli of 1.8 GPa in N,Ndimethylformamide, which is the lowest among those reported so far for porous metal–organic crystals.