Synthesis of M-UiO-66 (M = Zr, Ce or Hf) employing 2,5-pyridinedicarboxylic acid as a linker: defect chemistry, framework hydrophilisation and sorption properties

Abstract

Metal-organic frameworks of general composition [M(OH)(O)(PDC)(Cl)(HO)] with M = Zr, Ce, Hf; PDC = 2,5-pyridinedicarboxylate and 0 ≤ x ≤ 2 were obtained under reflux using formic, nitric or acetic acid as an additive. Rietveld refinements carried out using a fixed occupancy of the linker molecules according to the results of thermogravimetric measurements confirmed that the MOFs crystallize in the UiO-66 type structure and demonstrate that the structural models describe the data well. Further characterization was carried out by NMR spectroscopy, thermogravimetric analysis, Zr K-edge EXAFS- and Ce L-edge XANES measurements. To highlight the influence of the additional nitrogen atom of the pyridine ring, luminescence and vapour sorption measurements were carried out. The hydrophilisation of the MOFs was shown by the adsorption of water at lower p/p (<0.2) values compared to the corresponding BDC-MOFs (0.3). For water and methanol stability cycling adsorption experiments were carried out to evaluate the MOFs as potential adsorbents in heat transformation applications.

C2–H Arylation of Indoles Catalyzed by Palladium‐Containing Metal‐Organic‐Framework in γ‐Valerolactone

“…UiO‐66‐PDC was synthesized according to a slightly modified literature procedure . First, 0.733 g 2,5‐pyridinedicarboxylic acid, 0.730 g terephthalic acid, and 2.868 g ZrOCl 2 ⋅8 H 2 O were mixed in 90 mL formic acid and 10 mL deionized water.…”

The Impact of Synthesis Method on the Properties and CO2 Sorption Capacity of UiO-66(Ce)

“…To our best knowledge, UiO-66(Ce) has not been obtained yet via the sonochemical route. According to recently published [12][13][14]32], cerium-based UiO-66 structures were obtained only by solvothermal synthesis.…”

Rietveld Refinement of MIL‐160 and Its Structural Flexibility Upon H2O and N2 Adsorption

“…Zirconium based MOFs are often considered extraordinarily stable due to the high charge of the cations and the resulting strong metal‐linker bonds . However, under the harsh hydrothermal testing conditions several of these compounds exhibit a rapid decrease in sorption capacity due to framework hydrolysis . Higher stabilities were reported for several aluminium based MOFs.…”