CFA-15-a perfluorinated metal-organic framework with linear 1-D CuII-chains containing accessible unsaturated, reactive metal centres

The synthesis and crystal structure of the perfluorinated metal-organic framework CFA-15 (Coordination Framework Augsburg University-15), Cu-3(II)(tfpc)(2)(OH)(2)center dot DMF, as well as the crystal structure of its ligand (H-2-tfpc = 3,5-bis(trifluoromethyl)-1H-pyrazole-4-carboxylic acid) are described. The MOF crystallizes in the monoclinic crystal system within the chiral space group C2 (no. 5). It features a 3-D microporous framework with rhombic channels along the c-axis. The MOF is formed by 1-D chains of Cu(II) ions expanding in the c-direction, bridged by OH- groups, DMF molecules and tfpc(2-) ligands. Two different Cu(II) species are located within the structure, bridged in a {Cu1-Cu1-Cu2-Cu1-Cu1-Cu2} mode. By thermal treatment, it was possible to remove coordinated solvent molecules and generate free accessible, unsaturated and reactive metal centres. The structure of activated CFA-15 was refined via Rietveld method. DRIFT measurements, which were used to study adsorption of CO2 and NO in the MOF, showed a formation of a stable NO-CFA-15 complex. CFA-15 was further characterized by thermogravimetric analysis, variable temperature powder X-ray diffraction measurements, IR spectroscopy, as well as photoluminescence and gas sorption measurements. The isosteric heats of adsorption for CO, CO2, H-2 and O-2 were determined, and compared to DFT calculated sorption energies as well as to data reported in literature for similar materials.