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A very high catalytic activity in the cyanosilylation reaction was observed for MIL-101, a chromium based metal-organic framework; moreover, MIL-101 is also a remarkably stable support for palladium in hydrogenation reactions, with significantly higher activity than e.g. palladium on activated carbon.

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The targeted synthesis of a desired stereomer plays a key role in life sciences, especially in the production of drugs. Up to date, this area is dominated by homogeneous chiral catalysts. Metal-Organic Frameworks (MOFs), a new class of porous materials, consisting of metal-oxo-clusters and multifunctional ligands could offer a platform for chiral heterogeneous catalysts combining the efficiency and in particular selectivity observed for homogeneous asymmetric catalysts with the advantages of heterogeneous catalysis. This review summarizes strategies to obtain chiral Metal-Organic Frameworks and gives an overview about reactions that have been successfully conducted using chiral MOFs as asymmetric catalysts. In addition, some examples highlighting the stereoselective adsorption properties of chiral Metal-Organic Frameworks are given.

Dedicated to Professor Rüdiger Kniep on the occasion of his 65th birthdayMetal-organic frameworks (MOFs) have emerged as a new class of crystalline porous materials with extraordinary high adsorption capacities and pore sizes exceeding those of traditional porous materials.[1] MOFs are considered as promising specific catalysts [2] and hydrogen storage materials [3] because of the presence of open, accessible metal centers. These active sites can be generated, for example, in square paddle-wheel units {M 2 (O 2 C) 4 } (M = Cu, Ni, Zn, Co, Mo) [4,5] and trigonal {M 3 (m 3 -O)(O 2 C) 6 } clusters (M = Sc, Cr, Fe, Ni, Al, In). [6][7][8] Such clusters act as nodes or secondary building units (SBUs) connected through multifunctional carboxylate linkers, resulting in highly porous three-dimensional networks, such as HKUST-1, [4] MIL-100, [7] or MOF-14.[9] For zinc-containing MOFs, the octahedral {Zn 4 O(O 2 C) 6 } SBU is a common motif, [10] resulting in materials with very high porosity and exceptional hydrogen-storage properties. [11] However, the metal sites are coordinatively saturated in these structures.Herein, we present the synthesis, structure, and properties of the new porous material DUT-9 (DUT = Dresden University of Technology) formed by btb linkers (btb = benzene-1,3,5-tribenzoate) and {Ni 5 (m 3 -O) 2 (O 2 C) 6 } clusters, which is a novelty in MOF chemistry. {Ni 5 O 2 (btb) 2 } has a high concentration of open metal sites per cluster and a very high porosity that is unknown for nickel-containing MOFs to date. The phase purity and stability of the compound was monitored by PXRD analysis (Supporting Information, Figure S6).The crystal structure of DUT-9 (space group R3 ) contains a {Ni 5 (m 3 -O) 2 (CO 2 ) 6 (L) 4 (H 2 O) 4 } (L= DMF, DEF) cluster (distorted octahedral SBU). Five octahedrally coordinated nickel atoms are bridged by two m 3 -O atoms and six carboxylate groups (Figure 1 a). The five nickel atoms are coplanar. The central nickel atom Ni1 is coordinated by four carboxylate oxygen atoms and the two m 3 -O atoms. Ni2 and Ni3 and their symmetry equivalents Ni2* and Ni3* (* 1Àx, Ày, Àz), are linked to three carboxylate oxygen atoms, an oxygen atom of formamide, a water oxygen atom, and a m 3 -O atom. The four DMF/DEF and four water molecules can be removed to create accessible metal sites in the structure (Supporting information, Figure S2). The SBUs are arranged in parallel Kagome nets stacked in the ABC sequence perpendicular to the c direction (Supporting Information, Figure S4 and S5). Each SBU is connected to four ligands within a layer and to two additional linkers belonging to the two adjacent layers each (up and below a given layer), thus forming a structure with the topology of a (3,6)-connected net, which is unknown to date (for details, see the Supporting Information).

This work is focusing on the potential application of metal-organic frameworks as porous materials in heterogeneous catalysis where the substrate is in solution. The understanding of such a liquid-phase heterogeneous catalytic process requires adsorption equilibrium data in solution. For this purpose several metal-organic frameworks were synthesized as reference materials and tested as adsorbents for the adsorption of substrate molecules such as styrene or ethylcinnamate from the liquid phase. The adsorption capacity strongly depends on the polarity of the substrate with respect to the solvent. In several instances solvent and polarity effects are heavily superimposed on the pore size effects. Adsorption isotherms, rates and hydrogenation of the substrates are reported and discussed.