Control of interpenetration and structural transformations in the interpenetrated MOFs

Interpenetration is an intriguing phenomenon in metal–organic framework (MOF) structures and considered as one of the framework isomers or supramolecular isomers. This has remarkable influence on the surface area, size and shape of the pores in MOFs. Altering the degree of interpenetration (DOI) significantly modifies the thermal stability and density of the frameworks as well as non-covalent interactions with the guest molecules and between the interpenetrated nets. As a consequence, DOI is expected to provide a greater control on the properties such as sorption of guest molecules, separation, optical properties, thermal stability, and chemical reactivity. In this focused review, we illustrated the influence of experimental conditions on the DOI with selected examples. Further, structural transformation in the solid state between different DOIs in MOFs with same topologies are discussed in detail. In addition, some unusual structural changes between different interpenetrated MOFs with varied dimensionalities and topologies are also exemplified.