Docking of CuI and AgI in Metal-Organic Frameworks for Adsorption and Separation of Xenon.

We present a metal docking strategy utilizing the precise spatial arrangement of organic struts as metal chelating sites in a MOF. Pairs of uncoordinated N atoms on adjacent pyrazole dicarboxylate linkers distributed along the rod-shaped Al-O secondary building units in MOF-303 [Al(OH)(C5 H2 O4 N2 )] were used to chelate CuI and AgI with atomic precision and yield the metalated Cu- and Ag-MOF-303 compounds [(CuCl)0.50 Al(OH)(C5 H2 O4 N2 ) and (AgNO3 )0.49 Al(OH)(C5 H2 O4 N2 )]. The coordination geometries of CuI and AgI were examined using 3D electron diffraction and extended X-ray absorption fine structure spectroscopy techniques. The resulting metalated MOFs showed pore sizes matching the size of Xe, thus allowing for binding of Xe from Xe/Kr mixtures with high capacity and selectivity. In particular, Ag-MOF-303 exhibited Xe uptake of 59 cm3  cm-3 at 298 K and 0.2 bar with a selectivity of 10.4, placing it among the highest performing MOFs.