Solvent-Free Synthesis of Fumarate-Based Metal-Organic Frameworks with Resonant Acoustic Mixing

Metal-organic frameworks (MOFs) are versatile materials, but their synthesis often requires harsh conditions, toxic precursors, or organic solvents. Recently, MOFs have been produced using resonant acoustic mixing (RAM), a form of mechanochemistry that provides a greener alternative to conventional methods. In this study, we demonstrate the solvent-free synthesis of fumarate-based MOFs using RAM at room temperature and atmospheric pressure. Iron fumarate (MIL-88A(Fe)) was successfully produced with a BET surface area of 209 m² g^-1, comparable to mechanochemical grinding. The synthesis was scaled up to a 10.5 g yield using RAM for 20 min and without solvent. Aluminum fumarate (MIL-53(Al)-FA) was also synthesized with a high surface area (790 m² g^-1), while attempts to synthesize the calcium fumarate MOF (CaFu) instead resulted in the non-porous coordination polymer, calcium fumarate trihydrate. These results demonstrate the potential of RAM as a more sustainable approach to MOF synthesis.