Defective Metal‐Organic Frameworks

Abstract

The targeted incorporation of defects into crystalline matter allows for the manipulation of many properties and has led to relevant discoveries for optimized and even novel technological applications of materials. It is therefore exciting to see that defects are now recognized to be similarly useful in tailoring properties of metal-organic frameworks (MOFs). For instance, heterogeneous catalysis crucially depends on the number of active catalytic sites as well as on diffusion limitations. By the incorporation of missing linker and missing node defects into MOFs, both parameters can be accessed, improving the catalytic properties. Furthermore, the creation of defects allows for adding properties such as electronic conductivity, which are inherently absent in the parent MOFs. Herein, progress of the rapidly evolving field of the past two years is overviewed, putting a focus on properties that are altered by the incorporation and even tailoring of defects in MOFs. A brief account is also given on the emerging quantitative understanding of defects and heterogeneity in MOFs based on scale-bridging computational modeling and simulations.

Controllable Synthesis of Porphyrin‐Based 2D Lanthanide Metal–Organic Frameworks with Thickness‐ and Metal‐Node‐Dependent Photocatalytic Performance

“…Metal–organic frameworks (MOFs), a kind of crystalline porous materials constructed by connecting metal ions/clusters and bridging organic ligands via coordination bonds, have been extensively studied for applications in catalysis, gas storage and separation, drug delivery, and sensing owing to their tailorable structure and function, ultrahigh porosity and large surface area. Although many promising methods have been applied to prepare multifunctional MOFs, such as modulating crystal structure and compounding with other functional materials, their performance still needs great improvement. Since the discovery of graphene, two‐dimensional (2D) materials, which possess the characteristics of large surface area and relatively high surface energy, have been found that the unique physicochemical properties cannot be achieved by their bulk counterparts …”

Low‐Dimensional Metal‐Organic Frameworks and their Diverse Functional Roles in Catalysis

“…Even among hierarchical MOFs, those with interconnected extrinsic meso‐/macropores will have significant advantages in catalysis. There is also a need to further understand how defect sites could affect catalysis . As low‐dimensional MOFs have a greater external surface area; these surfaces are typically defective.…”

Switching in Metal–Organic Frameworks

“…These materials have unique structural features, such as permanent, regular porosity, and large internal surface areas . The enormous variety in MOF structures arises from the diversity of choice in metal structural building units (SBUs) and organic linkers, leading to an extensive spectrum of physical and chemical properties . This, along with the presence of various interactions, including hydrogen bonding, van der Waals interactions, π–π stacking, and metal coordination, have made MOFs promising functional compounds.…”