Mechanochemistry: Toward green synthesis of metal-organic frameworks

Metal-organic frameworks (MOFs) have attracted a special attention due to outstanding porosity, adjustable pore sizes, and huge opportunities in varying organic-inorganic compositions. Enormous studies conducted so far on MOFs indicate their high potential in catalysis, gas adsorption, drug delivery, water treatment, energy storage, among others. However, mass production of MOFs is still limited mainly due to the non-economic, non-green and complex synthesis methods. Mechanochemistry is an alternative solution for efficient and environmentally friendly syntheses of various MOFs. Fast and solvent-free or solvent-less mechanosynthesis seems to be a very powerful versatile method for obtaining these advanced porous materials. The mechanochemical concept was used for the preparation of various MOFs including the most popular structures: MOF-5, ZIF-8, HKUST-1, MIL 101, UiO-66. These MOFs feature high specific surface areas, comparable to those prepared by conventional solvent-based methods. Furthermore, mechanochemistry was successfully used for the synthesis of non-conventional multimetallic MOFs and previously unreported solid phases. This review shows the recent developments, challenges and perspectives of green synthesis of diverse MOF structures using mechanochemistry. Besides describing the mechanochemical synthesis of MOFs, some achievements in green applications are also summarized. Importantly, current trends in research suggests for further development of these fields i.e., harmful gas adsorption, water treatment, and energy storage.