Preface: Special topic on Metal-organic frameworks (MOFs)

Metal-organic frameworks, MOFs, are coordination networks with organic ligands and voids. At the fundamental level, MOFs epitomize the beauty of chemical structures and the power of combining organic and inorganic chemistry, two disciplines that are often regarded as disparate. MOFs have recently emerged as an extensive class of crystalline materials with ultrahigh porosity and internal surface areas. These properties of MOFs, together with the extraordinary degree of variability for both the organic and inorganic components of their structures, bring great promise for a large, diverse array of applications. MOF research has been one of the most active areas in chemistry with an extraordinary pace since the 1990s. Our search of the literature, through the Web of Science, using the keywords “metal-organic frameworks” showed that there were 30412 publications from 1990 to May 2016. Analyses of these publications in Figure 1 show that gas sorption, catalysis and fluorescence are the top three subjects of MOF research, while studies of MOFs for battery application and electrocatalysis have been very active lately. The concerns about the environment and energy supplies have led to the investigations of MOFs for gas adsorption such as hydrogen and methane storage, carbon dioxide capture, and the selective separation of light hydrocarbons. MOFs as fluorescent sensors could detect many types of hazardous substances such as metal ions, negative ions, and explosives. Porous MOFs, with their high efficiency and retrievability, are considered as promising candidates for Figure 1 The ratio of the papers on the different MOF topics from 1990 to May 2016.