A porous copper-organic framework with intersecting channels and gas adsorption properties.

A solvothermal reaction of CuI with a bifunctional organic ligand 3,5-pyridinedicarboxylic acid (Hpdc) afforded a novel heterovalent copper-organic framework, [(CuI)Cu(pdc)(HO)]·4DMSO (1) (DMSO = dimethyl sulfoxide). Compound 1 was structurally characterized by single-crystal X-ray diffraction analyses and further characterized by infrared spectroscopy (IR), powder X-ray diffraction (PXRD), elemental analyses and thermogravimetric analyses (TGA). Structural analysis indicates that two kinds of common secondary building units (SBUs) coexist in this 3D network. The linkage of Cu and I generates [CuI] subunits and the connection of Cu with carboxyl-O atoms gives rise to binuclear paddle-wheel [Cu(COO)(HO)] moieties. In compound 1, two different SBUs are bridged with pdc ligands to construct a micro-sized cage with an internal spherical cavity. Through a cage-to-cage connection, the 3D porous framework is formed which features intersecting 1D channels. Gas sorption measurements were conducted on the activated 1, showing a H uptake of 1.46 wt% at 77 K and under 1 bar with a high initial adsorption enthalpy of 8.2 kJ mol. Moreover, compound 1 has excellent adsorption selectivity for CO over N and CH.