Wobbling and Hopping: Studying Dynamics of CO2 Adsorbed in Metal–Organic Frameworks via 17O Solid-State NMR

Knowledge of adsorbed gas dynamics within microporous solids is crucial for the design of more efficient gas capture materials. We demonstrate that 17O solid-state NMR (SSNMR) experiments allow one to obtain accurate information on CO2 dynamics within metal–organic frameworks (MOFs), using CPO-27-M (M = Mg, Zn) as examples. Variable-temperature (VT) 17O SSNMR spectra acquired from 150 to 403 K yield key parameters defining the CO2 motions. VT 17O SSNMR spectra of CPO-27-Zn indicate relatively weaker metal–oxygen binding and increased CO2 dynamics. 17O SSNMR is a sensitive probe of CO2 dynamics due to the presence of both the quadrupolar and chemical shielding interactions, and holds potential for the investigation of motions within a variety of microporous materials.