Microwave-assisted dry-gel conversion-a new sustainable route for the rapid synthesis of metal-organic frameworks with solvent re-use.

Microwave-assisted dry-gel conversion (MW-DGC) combines the advantages of concentrated reactants in DGC with fast heating by microwave irradiation. This novel combination allows drastically decreasing the amount of solvent needed for synthesis and reaction times with the energy needed. Furthermore, MW-DGC allows for the recovery and re-use of the reaction solvent and thereby can significantly reduce the overall solvent waste in the syntheses of the four important MOFs MIL-100(Fe) (Basolite F300), UiO-66, MIL-140A and aluminium fumarate (Alfum, Basolite A520). All the MOF products obtained from MW-DGC showed satisfying yields, crystallinity and porosity in comparison with the industrial benchmarks Basolite F300 and Basolite A520. Moreover, MW-DGC also advantageously leads to a hierarchical micro-mesoporous Alfum material different to that from other synthesis methods.