Engineering the Porosity and Active Sites in Metal–Organic Framework

The endless structural features make the metal–organic framework (MOF) one of the promising classes of modern-day material. The basic features associated with MOF structure are high surface area, unique structural properties, and tunable chemical functionality. MOF is a highly crystalline material with a large surface area and a diverse range of tailorable porous framework structures. The porous framework structure of MOF arises due to the self-assembly of organic linkers (ligands) and metal nodes. Therefore, the possible active sites in MOF are located near the pores, metal nodes, and ligand centers. The functional tunable properties of MOF provide numerous opportunities for structural modifications and make them ideal for highly efficient catalytically active material by active site engineering of pores, metal nodes, and ligand centers. The resultant structurally modified MOFs are a unique class of catalytic material and have been successfully employed in several heterogeneous catalytic transformations. Additionally, MOF tends to carry homogeneously distributed metallic sites or other nanoscopic guest particle as the additional active centers, which can be used for a selected appointed catalytic reaction. The major challenges associated with the structurally modified MOF through active site engineering are their controlled synthesis strategies, the exact estimation of the modifications, and the apparent stability of the modified MOF. The idea of MOF framework modification is attributed to the modifications in the physical and chemical environment of the framework regions where the framework stability and reactivity altered and ultimately brought different interactions with the target species for organic transformation.