Controlling the Synthesis of Metal-Organic Framework UiO-67 by Tuning Its Kinetic Driving Force

The successful synthesis of metal-organic framework (MOF) compounds relies on an intricate interplay between the components of the synthesis liquor at the given synthesis conditions. Herein, we explore the interdependence of modulator, linker, and solvent amounts in the synthesis of the Zr-based MOF, UiO-67. Our study suggests that control of linker vacancy defects in UiO-67 is feasible by tuning the ratios of these components, and that such control derives from recognizing the kinetic driving forces during MOF crystal growth. Importantly, we show that linker vacancy defects (and modulator molecules occupying linker sites) can be reduced by limiting the solvent amount to maintain a saturated concentration of linker throughout the synthesis. The method enables formation of UiO-67 with an ideal 1:1 ratio between Zr and the 4,4'-biphenyldicarboxylic acid linker, without surplus linker in the mother liquor or additional post-synthetic steps, and reduces the amount of dimethylformamide (DMF) solvent to less than 20% the amount in previously reported procedures.