CO2 Dynamics in a Metal-Organic Framework with Open Metal Sites

Metal-organic frameworks (MOFs) with open metal sites are promising candidates for CO2 capture from dry flue gas. We applied in situ C-13 NMR spectroscopy to investigate CO2 adsorbed in Mg-2(dobdc) (H(4)dobdc = 2,5-dihydroxyterephthalic acid; Mg-MOF-74, CPO-27-Mg), a key MOF in which exposed Mg2+ cation sites give rise to exceptional CO2 capture properties. Analysis of the resulting spectra reveals details of the binding and CO2 rotational motion within the material. The dynamics of the motional processes are evaluated via analysis of the NMR line shapes and relaxation times observed between 12 and 400 K. These results form stringent and quantifiable metrics for computer simulations that seek to screen and improve the design of new MOFs for CO2 capture.