Ultra-High Porosity in Metal-Organic Frameworks

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Science  01 Jul 2010:
DOI: 10.1126/science.1192160


Crystalline solids with extended non-interpenetrating three-dimensional crystal structures were synthesized that support well-defined pores with internal diameters of up to 48 Angströms. The Zn4O(CO2)6 unit was joined with either one or two kinds of organic link, 4,4',4''-(benzene-1,3,5-triyltris(ethyne-2,1-diyl))tribenzoate (BTE), 4,4',4''-(benzene-1,3,5-triyl-tris(benzene-4,1-diyl))tribenzoate (BBC), 4,4',4''-benzene-1,3,5-triyl-tribenzoate (BTB)/2,6-naphthalenedicarboxylate (NDC), and BTE/biphenyl-4,4'-dicarboxylate (BPDC), to give four metal-organic frameworks, MOF-180, 200, 205, and 210, respectively. Members of this series of MOFs show exceptional porosities and gas (hydrogen, methane, and carbon dioxide) uptake capacities. For example, MOF-210 has a Brunauer-Emmett-Teller surface area of 6,240 m2g-1 and a carbon dioxide storage capacity of 2,870 mg g-1. The volume-specific internal surface area of MOF-210 (2,060 m2 cm-3) is equivalent to the outer surface of nanoparticles (3 nm cubes) and near the ultimate adsorption limit for solid materials.