Combining In Situ Techniques XRD, IR, and C 13 NMR and Gas Adsorption Measurements Reveals CO2 Induced Structural Transitions and High CO2 CH4 Selectivity for a Flexible Metal Organic Framework JUK 8

Abstract

Flexible metal organic frameworks MOFs are promising materials in gas related technologies. Adjusting the material to processes requires understanding of the flexibility mechanism and its influence on the adsorption properties. Herein, we present the mechanistic understanding of CO2 induced pore opening transitions of the water stable MOF JUK 8 [Zn oba pip ]n, oba2 4,4 amp; 8242; oxybis benzenedicarboxylate , pip 4 pyridyl functionalized benzene 1,3 dicarbohydrazide as well as its potential applicability in gas purification. Detailed insights into the global structural transformation and subtle local MOF adsorbate interactions are obtained by three in situ techniques XRD, IR, and 13CO2 NMR . These results are further supported by single crystal X ray diffraction SC XRD analysis of the solvated and guest free phases. High selectivity toward carbon dioxide derived from the single gas adsorption experiments of CO2 195 and 298 K , Ar 84 K , O2 90 K , N2 77 K , and CH4 298 K is confirmed by high pressure coadsorption experiments of the CO2 CH4 75 25 v v mixture at different temperatures 288, 293, and 298 K and in situ NMR studies of the coadsorption of 13CO2 13CH4 50 50 v v; 195