Mechanochemistry beyond synthesis: An alternative pathway for overcoming the challenges in metal-organic frameworks

Abstract

Mechanochemistry offers a sustainable and efficient alternative to traditional solvothermal methods for advanced porous materials. In particular, it has been widely applied to the synthesis of metal-organic frameworks (MOFs), a representative class of porous materials with high surface area and tunable structures. By applying mechanical force through ball milling or twin-screw extrusion, activation barriers are lowered in the free-energy landscape, enabling rapid bond formation in minutes with minimal or no solvent. Recently, mechanochemistry has gained attention not only for an alternative method for conventional MOF syntheses but also as a way to reach structures and reaction pathways that are difficult to access with traditional methods. In this review, we present four case studies in which mechanochemistry was leveraged to overcome key limitations of MOFs, and we examine how these strategies address those challenges. This review covers four key applications. First, continuous, kilogram-scale production of benchmark MOFs such as UiO-66-NH2, HKUST-1, and ZIF-8 has been achieved by twin-screw extrusion under water-assisted, solvent-reduced conditions, reaching space-time yields up to 1 x 105 kg m-3 day-1. Second, direct mechanochemical routes achieve MOFs inaccessible by solvothermal synthesis, including imine-linked PCN-161 and heterometallic [(PdM)3(BTC)4]n materials in a single milling step. Third, sustainable recycling has been demonstrated by converting PET waste into BDC-based MOFs and by reconstructing hydrolyzed MOF-5, MOF-177, UiO-67, and ZIF-65 into their original structures. Fourth, gentle encapsulation has embedded enzymes in MOF and COF hosts, preserving native activity and conferring resistance to acid and proteases. In each case, tuning milling parameters such as ball size, frequency, milling media, and additive loading controls force magnitude and reaction pathways to direct defect formation, nucleation kinetics, and crystal growth. To further advance the field, truly solvent-free protocols must be developed, scale-up should expand to diverse and complex structures, and deeper mechanistic insight is needed through in situ monitoring and modeling. Integrating mechanochemistry with complementary stimuli and sustainable raw materials will overcome diverse challenges in MOFs, enabling closed-loop lifecycles and paving the way for advanced applications.