Generalized Approach for Rapid Aqueous MOF Synthesis by Controlling Solution pH

Metal–organic frameworks (MOFs) are a promising class of functional materials with applications in catalysis, separations, electronics, and drug delivery, among others. Despite a range of techniques utilized for MOF synthesis, a generalizable and scalable approach has yet to be developed for producing MOFs without using environmentally damaging organic solvents. Here, we look at MOF synthesis as a reaction in an aqueous medium and propose new methods of measuring conversion and selectivity. We show that controlling reactant speciation via pH is a generalizable approach to producing the prototypical MOFs UiO-66, UiO-66-NH2, ZIF-L, and HKUST-1 with space–time yields (STY) of over 2250 kg m–3 day–1, which is a 1 order of magnitude improvement for zirconium-based MOFs. We show that UiO-66-NH2 crystallization is complete in 5 min at room temperature, with 70% of the extent of reaction completed by 30 s. Finally, we apply the rapid synthesis approach to coating cotton fabric with up to 20 wt % UiO-66-NH2 using a sequential dip-coating (SQD) technique and demonstrate particulate matter (PM1–4) filtration up to 85%. This work shows a green-chemistry-based, generalizable pathway to rapid synthesis for multiple MOFs and demonstrates its utility for filtration applications. The ability to produce alternative filtration materials is especially relevant under pandemic conditions, where SQD offers a rapid and high-throughput manner of providing air filtration by modifying commonly available textile materials.