Chiral Functionalization of a Zirconium Metal-Organic Framework (DUT-67) as a Heterogeneous Catalyst in Asymmetric Michael Addition Reaction.

DUT-67, an 8-connected zirconium and 2,5-thiophenedicarboxylate-based metal-organic framework (MOF), was postsynthetically functionalized by l-proline via solvent-assisted linker incorporation to obtain a chiral base catalyst. The parent monocarboxylate could be almost completely exchanged by l-proline after 5 days of treatment. The resulting chiral DUT-67 was demonstrated to be a promising heterogeneous catalyst for the asymmetric Michael addition of cyclohexanone to trans-β-nitrostyrene with excellent yield (up to 96%) and enantioselectivity comparable to that of l-proline in homogeneous reaction (ee of approximately 38%).

The origin of the measured chemical shift of Xe in UiO-66 and UiO-67 revealed by DFT investigations.

The NMR chemical shift of the xenon isotope Xe inside the metal-organic frameworks (MOFs) UiO-66 and UiO-67 (UiO - University of Oslo) has been investigated both with density functional theory (DFT) and in situ high-pressure Xe NMR measurements. The experiments reveal a decrease of the total chemical shift comparing the larger isoreticular MOF (UiO-67) with the smaller one (UiO-66), even though one may expect an increase due to the higher amount of adsorbed Xe atoms. We are able to calculate contributions to the chemical shift individually.

Metal-Organic Frameworks for Thin-Layer Chromatographic Applications.

Preparation of thin-layer chromatographic (TLC) plates based on metal-organic frameworks (MOFs) as porous stationary phases is described. DUT-67 (DUT = Dresden University of Technology), a zirconium based MOF, was used in combination with a fluorescent indicator as stationary phase for analyzing a small selection of a wide spectrum of relevant analytes. The successful separation of benzaldehyde from trans-cinnamaldehyde and 4-aminophenol from 2-aminotoluene is reported as a model system using optimized eluent mixtures containing acetic acid.

The modulator driven polymorphism of Zr(IV) based metal-organic frameworks.

The reaction of ZrCl and 2,5-thiophenedicarboxylic acid (Htdc) in the presence of trifluoroacetic acid (Htfa) as modulator results in the formation of the new metal-organic framework (MOF) named DUT-126 (DUT = Dresden University of Technology). The nature and concentration of modulators are found to be decisive synthetic parameters affecting the topology of the formed product. DUT-126 ( HBR: ) extends the series of polymorphs differing in topology, namely DUT-67 ( REO: ), DUT-68 ( BON: ) and DUT-69 ( BCT: ) to four, where DUT-67 and DUT-68 show the same eight-connected secondary building units as in DUT-126.

Postsynthetic Inner-Surface Functionalization of the Highly Stable Zirconium-Based Metal-Organic Framework DUT-67.

A postsynthetic functionalization approach was used to tailor the hydrophobicity of DUT-67, a metal-organic framework (MOF) consisting of 8-connected Zr6O6(OH)2 clusters and 2,5-thiophenedicarboxylate as the ligand, using postsynthetic exchange of the modulator by fluorinated monocarboxylates. Water adsorption isotherms demonstrated that, by the incorporation of such hydrophobic molecules, the hydrophobicity of the inner surface of the network can be tuned. Furthermore, tolerance of the material toward the removal of adsorbed water can be significantly enhanced compared to the parent DUT-67 MOF.