Metal-Organic Frameworks

Metal-organic frameworks (MOFs) are a relatively young class of porous materials. They consist of inorganic complexes as nodes connected by multifunctional organic molecules (linkers). Highly porous MOFs reach records in terms of storage capacities for gases and vapors. The main characteristics of MOFs responsible for the success of them as adsorbents are crystallinity, modular composition, as well as exceptionally high specific surface areas and pore volumes. The chapter outlines structural building principles of MOFs and describes a few prototypical structures with value for gas storage. Also important characteristics such as pore size distribution and inner surface functionality are controllable in MOFs by the chemistry of the building blocks. As a consequence, MOF materials provide a platform to precisely study the gas adsorption from theoretical and experimental point of view and also to reach ideal material characteristics for the adsorption of the molecules of interest. Moreover, the intrinsic flexibility of the MOFs, leading to structural transformations and unique stepwise adsorption behavior not observed for rigid porous materials, opens new horizons for the design of effective “smart” adsorbents.