What is MOFs and COFs Compound?
Metal-organic frameworks (MOFs) are a new class of porous materials with high specific surface area that are linked by metal ions or ion clusters and organic molecules through coordination bonds. Covalent organic frameworks (COFs) are new organic porous materials mainly composed of small organic monomers interconnected by strong covalent bonds. Both MOFs and COFs are porous materials with a certain spatial structure, characterized by large specific surface area and porosity, controllable chemical and physical properties, low skeletal density, permanently open pore structure, and diversified synthesis strategies. However, COFs without metal ions have better acid and alkali resistance and thermal stability. These characteristics make MOFs and COFs materials have important application prospects in many fields such as catalysis technology, gas separation and storage, optoelectronic materials, environment and energy.
Figure 1. Relative structure of MOFs and COFs
What are the Application of MOFs and COFs Compound?
- MOFs and COFs Compound for Separation Analysis Field: In MOFs and COFs, organic ligands or small organic monomers are ordered to form pores of uniform size. Adjusting the size, polarity, species or coordination mode of the molecule can control the shape, size and hydrophilicity and hydrophobicity of the pore, which has important applications in the field of separation and analysis. In addition, post-modification of MOFs and COFs is also an important way to regulate their surface properties. The basic method is to use special functional groups (such as -NH2, -OH, -CHO) distributed on the surface of MOFs and COFs as reaction sites, or modify some selective functional groups to realize the identification and detection of molecular ions.
- MOFs and COFs Compound for Gas Adsorption and Storage Field: MOFs have the advantages of ultra-high specific surface area, large porosity, diverse and tunable pore structure, and relatively mild preparation conditions, which can be used for gas adsorption, and has strong gas adsorption capacity for carbon, nitrogen and sulfur atmospheric pollutants. COFs have great advantages in gas storage due to their low density, large specific surface area, controllable pore size distribution, stable rigid topology and good modifiability. COFs materials mainly focus on the storage of hydrogen, methane, carbon dioxide and ammonia and the adsorption of organic molecular pollutants.
- MOFs and COFs Compound for Catalysis Field: The pores of MOFs are composed of metal centers and organic linkers, and the composition and structure of MOFs can be tuned by using a variety of metal nodes and a theoretically unlimited number of organic linkers. The metal nodes of MOFs can purposefully select catalytically active metal elements to construct different types of catalytic materials. COFs are formed by covalently linked multidentate organic structures, and their composition, structure, and function are highly tunable. Generally, COFs are connected by boronic acid, boron, imine, and hydrazone. At present, the reactions using COFs as catalyst supports mainly include oxidation reactions, carbon-carbon coupling reactions, acylation reactions, photocatalytic reactions, and asymmetric addition reactions.
- MOFs and COFs Compound for Optoelectronic Materials Field: MOFs are attractive electrode materials due to their large specific surface area, interconnected pores, and well-ordered framework structures. The overall performance of solar cells can be improved by designing functionalized MOFs thin films. COFs extend the π-conjugated system to the entire three-dimensional structure, which not only expands the delocalized range of π electrons, but also suppresses the π-π interaction between conjugated units. Therefore, COFs have high electron mobility and excellent photoconductivity. It can be applied to the fields of sensors and batteries.
- Fang Q, Gu S, Zheng J. 3D microporous base-functionalized covalent organic frameworks for size-selective catalysis[J]. Angewandte Chemie, 2014, 53(11), 2878-2882.