Synthetic strategies to obtain MOFs and related solids with multimodal pores

Abstract

Porous materials of regular pore sizes ranging from subnanometer to tens of nanometers find application in numerous fields such as gas adsorption and separation, catalysis, biology, drug delivery, and sensing. Metal-organic frameworks (MOFs) are one type of crystalline porous materials that due to the versatility in the synthesis, the wide range of possible compositions and the variety of crystal structures, strategies for post-synthetic modification and compounding are currently among the most researched porous materials. Their synthesis is done by using inorganic and organic components. Up to now, many MOFs with uniform porosity have been reported, but recently there is an increasing interest in the synthesis and properties of MOFs combining two or three types of pores. The use of various building units can generate heterogeneity in the MOF structure with the associated influence on the porosity, too. It is notable that pore heterogeneity can enhance the performance of MOFs in different applications that involve intracrystalline diffusion. Herein, the dependence of MOFs performance on their multimodal pores with synthesis strategies will be reviewed. This review shows several readily available synthesis procedures that lead to the creation of the variety of combinations in MOFs of bimodal pore systems such as micro- and mesopores or macropores, meso- and macropores, even three kinds of different pores. It will be shown that the synthesized multimodal pore MOFs with the various synthesis methods represent a new important concept for the design of advanced materials with enhanced properties and applications.