Metal-organic frameworks (MOFs) have emerged as materials for the capture of CO2 from post-combustion flue gases. The knowledge of gas binding mechanisms and the in-depth understanding of MOF structures are the key guiding basis for optimizing material design and predicting structure-property relationships. We propose to utilize the state-of-the-art solid-state NMR facilities and the high-performance super-computing capabilities at EMSL to investigate the MOF materials and guest-host interactions at the molecular level. Our proposal consists of three major focuses including the NMR spectroscopy of low-sensitivity quadrupolar nuclei such as 25Mg, 67Zn, and 91Zr that are critical binding sites for gas adsorption; the in-situ NMR experiments of adsorbed gas molecules under the temperatures and pressures relevant for practical applications; and a combination of computational approaches to interpret, simulate, and predict gas adsorption properties based on NMR observations.