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Owing to their high surface areas, tunable pore dimensions, and adjustable surface functionality, metal-organic frameworks (MOFs) can offer advantages for a variety of gas storage and gas separation applications. In an effort to help curb greenhouse gas emissions from power plants, we are developing new MOFs for use as solid adsorbents in post- and pre-combustion CO2 capture, and for the separation of O2 from air, as required for oxy-fuel combustion. In particular, MOFs with diamine-functionalized metal sites are demonstrated to operate via an unprecedented cooperative insertion mechanism, leading to high selectivities and working capacities for the adsorption of CO2 over N2 under flue gas conditions

Multicomponent adsorption measurements further show these compounds to be effective in the presence of water, while calorimetry and temperature swing cycling data reveal low regeneration temperatures compared to aqueous amine solutions. MOFs with redox-active coordinatively-unsaturated metal centers, such as the Fe2+ sites in Fe2(dobdc) (dobdc4– = 2,5-dioxido-1,4- benzenedicarboxylate) allow the selective adsorption of O2 over N2 via an electron transfer mechanism. The same material is demonstrated to be effective at 45 °C for the fractionation of mixtures of C1 and C2 hydrocarbons, and for the high-purity separation of ethylene/ethane and propylene/propane mixtures. In addition, it will be shown that certain structural features possible within MOFs, but not in zeolites, can enable the fractionation of hexane isomers according to the degree of branching or octane number. Finally, a new spin transition mechanism will be elaborated as a means of achieving cooperative CO adsorption.