High pressure structural transformation of selected metal organic frameworks – A theoretical investigation

Metal organic frameworks are susceptible to flexible structural transformations under the influence of external stimuli. Although guest dependent flexible transformations has been observed for several MOFs; but studies on pressure induced transformation is limited. In applications such as gas storage and separation, MOFs may encounter high pressures leading to change in structural behavior, porosity, etc. Hence it is important to study the effect of high pressure on MOF structure. Here we present high pressure induced structural transformations of 6 isoreticular MOFs: IRMOF-1, IRMOF-3, IRMOF-6, IRMOF-8, IRMOF-10 and IRMOF-14. Using molecular simulations we show that at high pressure these MOFs deformed to ∼50% of their original volume. This deformation is due to reorganization of the linkers and ZnO4 tetrahedra. There is large torsion along the dihedral angle O–C–C–C. Structural transformations for MOFs with substituted benzene organic linkers are reversible. For others reversibility depends on the presence of hydrogen in the crystal.