Solid-state NMR Studies of Host–Guest Interaction between UiO-67 and Light Alkane at Room Temperature

The host–guest interaction between adsorbent and adsorbate plays essential roles in the gaseous storage and chemical separation using metal–organic frameworks (MOFs). Solid-state NMR spectroscopy was employed to explore the interactions between light alkanes including methane, ethane, propane and a representative MOF, UiO-67 at room temperature. The existence of host–guest interaction between light alkanes and UiO-67 framework is clearly evidenced from two-dimensional 1 H– 1 H spin diffusion homonuclear correlation and 1 H– 13 C HETCOR with spin diffusion experiments. By fitting the spin diffusion buildup curves, it is found that methane is more readily to diffuse to the UiO-67 framework compared to ethane and propane. Moreover, the spin diffusion MAS NMR results reveal that methane is mainly adsorbed neighboring the metal cluster, whereas propane and ethane are preferentially present nearby the site away from the metal cluster due to the steric hindrance effect. The results presented herein would provide a better understanding of the structure–property relationship of MOFs in the alkane storage.