Heterometallic In(III)-Pd(II) Porous Metal-Organic Framework with Square-Octahedron Topology Displaying High CO Uptake and Selectivity toward CH and N.

The targeted synthesis of metal-organic frameworks (MOFs) with open metal sites, following reticular chemistry rules, provides a straightforward methodology toward the development of advanced porous materials especially for gas storage/separation applications. Using a palladated tetracarboxylate metalloligand as a 4-connected node, we succeeded in synthesizing the first heterobimetallic In(III)/Pd(II)-based MOF with square-octahedron (soc) topology. The new MOF, formulated as [InO(L)(HO)Cl]·n(solv) (1), features the oxo-centered trinuclear clusters, [In(μ-O)(-COO)], acting as trigonal-prismatic 6-connected nodes that linked together with the metalloligand trans-[PdCl(PDC)] (L) (PDC: pyridine-3,5-dicarboxylate) to form a 3D network. After successful activation of 1 using supercritical CO, high-resolution microporous analysis revealed the presence of small micropores (5.8 Å) with BET area of 795 m g and total pore volume of 0.35 cm g. The activated solid shows high gravimetric (92.3 cm g) and volumetric (120.9 cm cm) CO uptake at 273 K and 1 bar as well as high CO/CH (15.4 for a 50:50 molar mixture) and CO/N (131.7 for a 10:90 molar mixture) selectivity, with moderate Q for CO (29.8 kJ mol). Slight modifications of the synthesis conditions led to the formation of a different MOF with an anionic framework, having a chemical formula [MeNH][In(L)]· n(solv) (2). This MOF is constructed from pseudotetrahedral, mononuclear [In(-COO)] nodes bridged by four L linkers, resulting in a 3D network with PtS topology.