Metal–Organic Frameworks as Multifunctional Solid Catalysts

Metal–organic frameworks (MOFs) are often used as solid catalysts due to their abundant unsaturated metal sites, high surface area, and tunable pore volume. Possible strategies to enhance the catalytic activity of MOFs include generation of structural defects, introduction of electron withdrawing groups on the linker, and decreasing the dimensionality from 3D to 2D. Encapsulation of metal complexes or nanoparticles inside MOFs favors higher catalytic activity through synergism between the guest and MOF. MOFs can be designed as multifunctional catalysts having complementary types of sites to perform tandem processes comprising more than one elementary reaction. This review article describes the main reasons to use metal–organic frameworks (MOFs) as solid catalysts for liquid-phase reactions, including synthesis by design, high porosity in the micro-mesoporous range, and a high density of unsaturated transition-metal ions. The primary objective of this short review is to describe key current research strategies for improving activity, such as the role of structural defects, the synthesis of mixed-metal and mixed-ligand MOFs, and the synthesis of 2D materials with high lateral area-to-thickness aspect ratios. Emphasis is also placed on illustrating the potential offered by MOFs to develop multifunctional catalysts in tandem reactions. The final section contains our view on how the field will evolve towards implementing various industrial processes and expanding to electro- and photocatalysis. This review article describes the main reasons to use metal–organic frameworks (MOFs) as solid catalysts for liquid-phase reactions, including synthesis by design, high porosity in the micro-mesoporous range, and a high density of unsaturated transition-metal ions. The primary objective of this short review is to describe key current research strategies for improving activity, such as the role of structural defects, the synthesis of mixed-metal and mixed-ligand MOFs, and the synthesis of 2D materials with high lateral area-to-thickness aspect ratios. Emphasis is also placed on illustrating the potential offered by MOFs to develop multifunctional catalysts in tandem reactions. The final section contains our view on how the field will evolve towards implementing various industrial processes and expanding to electro- and photocatalysis.