Guest Inclusion of Methanol and Ethanol in Zirconium Metal-Organic Frameworks (Zr-Mofs)

Herein, we have investigated guest inclusion behavior of a Zr-MOF UiO-66 together with its acid–functionalized analogs. The synthesized materials were characterized by complimentary techniques including elemental analysis, BET surface area, FT-IR, PXRD, TG and DSC. On desolvation, both UiO-66 and UiO-66–COOH did not collapse whilst the UiO-66–(COOH)2 collapsed but was partially restored to the original structure on resolvation. Subtle changes in the binding mode of the carboxylate moiety were observed in the infrared region for the desolvated phases of these solids at 150 °C, reflected in changes in the PXRD and thermal properties. UiO-66 and UiO-66–COOH show a selective uptake of EtOH over MeOH while UiO-66–(COOH)2 revealed selective uptake of MeOH over EtOH. We postulate that the mesoporous compound, UiO-66, comprises hydrophilic pores which exhibited a high affinity for EtOH, whereas the macroporous UiO-66–(COOH)2 demonstrated selective MeOH uptake though the open zirconium sites at the expense of the coordinated water molecules. To the best of our knowledge, significant and selective uptake of MeOH and EtOH at room temperature using Zr-MOFs is reported in this work for the first time.