Effect of synthesis solvent on the breathing behavior of MIL-53(Al)

This work reports the effect of using dimethylformamide (DMF) as the solvent for synthesizing MIL-53(Al). This well-known breathing MOF is typically prepared using hydrothermal methods. The two materials synthesized in DMF at 120 °C and 220 °C show significant deviations from the breathing behavior exhibited by the material synthesized hydrothermally. Powder X-ray diffraction confirmed that MIL-53(Al) synthesized in DMF at 120 °C remains in the large-pore form under all conditions, while the other material synthesized at 220 °C undergoes a more gradual breathing transition than is observed for MIL-53(Al) prepared by traditional methods. Solid-state NMR was employed to elucidate additional structural information and gain insight into the role synthesis solvent plays on breathing behavior. The CO2 and water adsorption of these large-pore stabilized materials were studied, and the differences in adsorption behavior compared to MIL-53(Al) prepared by traditional methods was discussed.

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