Standing out from the vast majority of metal organic coordination polymers is the class of highly porous basic zinc carboxylates developed by Yaghi and co-workers.[1] Its prototype is MOF-5 (MOF = metal organic framework), in which {Zn 4 O} building blocks are linked together by terephthalate bridges to form a zeolite-like, cubic framework.[2] The extremely high specific surface area [2] of up to 4500 m 2 g À1 and a pore volume of 0.69 cm 3 cm À3 (for MOF-177), which has not been surpassed by any other crystalline substance, and thermal stability (up to 350 8C) opens up fascinating perspectives for the supramolecular host-guest chemistry.[3] Applications for these materials in miniaturized fuel cells and convenient gas-storage devices (for H 2 , CH 4 ), as gas sensors and for gas separation, as catalyst materials, and also for molecular electronics are emerging. [4] A report on the quantitative inclusion of C 60 and large polycyclic dye molecules (e.g. Astrazon Orange R) into the cavities of MOF-177 single crystals attracted our attention. [5] Could these MOF host lattices also be suitable to efficiently and selectively absorb typical metal organic chemical vapor deposition (CVD) precursors, provided these were volatile (gas absorption) or very soluble in nonpolar hydrocarbons and had matching size and shape to fit into the cavity? The release of the metal atoms of the precursors imbedded in the

The oxidation of CO over Ru/MgO and Ru/SiO2 catalysts was used as a simple model reaction to derive turnover frequencies at atmospheric pressure, which were observed to agree with kinetic data obtained under high-vacuum conditions with supported ruthenium catalysts and the RuO2(110) single-crystal surface. Thus, it was possible to bridge both the pressure and the materials gap. However, a partial deactivation was observed initially, which was identified as an activated process, both under net reducing and net oxidizing conditions. Temperature-programmed reduction (TPR) experiments were performed subsequently in the same reactor, to monitor the degree of oxidation, as a function of the reaction temperature and the CO/O2 reactant feed ratio. Using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements, the structural changes of the ruthenium catalysts during the oxidation of CO were confirmed, under relevant reaction conditions. Under net reducing conditions, only domains of RuO2 seem to exist on the metallic ruthenium particles, whereas, under net oxidizing conditions, the ruthenium particles were fully oxidized to bulk RuO2 particles, which may expose less-active facets, such as the RuO2(100)−c(2 × 2) surface.

Methanol catalysis meets chemistry under confined conditions. Methanol is regarded as one of the most important future energy sources. ZnO/Cu composite materials are very effective in heterogeneous catalysis for methanol production due to the so-called strong metal-support interaction effect (SMSI). Therefore, materials of superior structural design potentially representing model systems for heterogeneous catalysis are highly desired. Ultimately, such materials could help to understand the interaction between copper and zinc oxide in more detail than currently possible. We report the preparation of nanocrystalline, size-selected ZnO inside the pore system of ordered mesoporous silica materials. A new, liquid precursor for ZnO is introduced. It is seen that the spatial confinement significantly influences the chemical properties of the precursor as well as determines a hierarchical architecture of the final ZnO/SiO 2 nanocomposites. Finally, the ability of the materials to act as model systems in methanol preparation is investigated. The materials are characterized by a variety of techniques including electron microscopy, X-ray scattering, solidstate NMR, EPR, EXAFS, and Raman spectroscopy, and physisorption analysis.

Aus der Fülle metall-organischer Koordinationspolymere ragt die von Yaghi und Mitarbeitern entwickelte Stoffklasse hoch poröser basischer Zinkcarboxylate heraus.[1] Ihr Prototyp ist MOF-5 (MOF = Metal Organic Framework), in dem {Zn 4 O}-Baueinheiten über Terephthalat-Brücken zu einem Zeolith-ähnlichen, kubischen Raumnetz verknüpft sind. [2] Die von keiner anderen kristallinen Substanz übertroffenen, extrem hohen spezifischen Oberflächen [2] bis zu 4500 m 2 g À1und Porenvolumina von 0.69 cm 3 cm À3 (für MOF-177) sowie die thermische Stabilität (bis zu 350 8C) eröffnen faszinierende Perspektiven für die supramolekulare Wirt-GastChemie.[3] Anwendungen für miniaturisierte Brennstoffzellen und Gasspeicher (für H 2 , CH 4 ), als Gassensoren sowie als Trennmedien und Katalysatormaterialien, aber auch Mög-lichkeiten für die molekulare Elektronik zeichnen sich ab. [4] Ein Bericht über die quantitative Einlagerung von C 60 und großen polycyclischen Farbstoffmolekülen (z. B. Astrazon Orange R) in die Hohlräume von MOF-177-Einkristallen erregte unsere Aufmerksamkeit.[5] Sollten diese MOF-Wirtsgitter nicht ebenso effizient und selektiv auch typische metallorganische CVD-Vorstufen aufnehmen können, solange diese nur flüchtig (Gasabsorption) oder sehr gut löslich in Kohlenwasserstoffen wären und eine zum Hohlraum passen- [8] und [Au(CH 3 )(PMe 3 )] (3).[9]Die Größen-bzw. Formselektivität ist erwartungsgemäß sehr hoch. Für 2, das nur wenig mehr Raum beansprucht als 1 oder 3, findet man nur zwei statt vier eingelagerte Moleküle

Copper and zinc were introduced into mesoporous siliceous matrices with the goal of obtaining model methanol synthesis catalysts with intense interaction between copper and the ZnO promoter. The preparation methods included various aqueous routes starting from acetate solutions (into MCM-48) and a route involving an organometallic step-thermolysis of a liquid heterocubane of Zn 4 O 4 type ([CH 3 ZnOCH 2 CH 2 OCH 3 ] 4 ) in a wormhole-type silica of 5 nm average pore size-followed by aqueous Cu (nitrate) impregnation. The materials were characterized by XRD, nitrogen physisorption, N 2 O frontal chromatography, TPR, and EXAFS, and their methanol synthesis activity was measured at 493 K and normal pressure. In the aqueous preparations with acetate solutions, excessive formation of silicates (particularly zinc silicate) led to damage of the pore system. A significant delay in Cu reduction was assigned to the influence of micropores formed, together with some copper silicate formation. These samples exhibited poorly accessible Cu surface areas despite small Cu particle sizes indicated by EXAFS and disappointing methanol synthesis activity. In contrast to this, a highly active catalyst was obtained via the heterocubane route that meets industrial standards in terms of reaction rate per Cu surface area. Orientation studies (EXAFS at the CuK and ZnK edges) reflecting a redox behavior of the ZnO x component illustrate the potential of this catalyst type for use in basic studies of the Cu-ZnO x interaction in methanol synthesis catalysts.

The IR spectroscopic investigation of both the adsorption of carbon monoxide and the interaction of oxygen and CO on the surface of copper colloids is described for the first time. The copper colloids were produced by pyrolysis of [Cu(OCH(Me)CH(2)NMe(2))(2)] in hot n-hexadecylamine. Upon contact to synthetic air Cu/Cu(x)O core-shell particles are formed. The treatment of these particles with CO results in the reestablishment of pure Cu(0) particles. These results demonstrate that small molecules penetrate the ligand shell of the nanoparticles and reversibly adsorb at the surface without affecting the particle morphology and size distribution.

Free-standing, ZnO surface decorated Cu nanoparticles of 1-3 nm size were obtained by sequential co-pyrolysis of [Cu(OCHMeCH2NMe2)2] and ZnEt2 in squalane in the absence of additional surfactants and proved to be highly active quasi homogeneous catalysts for methanol synthesis from CO and H2.

A novel, non-aqueous, organometallic route to nanocomposite Cu@TiO2 materials is presented. TiO2 nanorods stabilized with oleic acid (OLA) were used as support for the photo-assisted deposition of Cu using the organometallic Cu(II) precursor [Cu(OCH(CH3)CH2N(CH3)2)2] (1). The copper precursor penetrates through the shell of OLA and is photo reduced to deposit Cu0 directly at the surface of the TiO2 rods. The obtained Cu decorated nanorods were still soluble in nonpolar organic solvents without change of the morphology of nanorods. The Cu@TiO2 colloid was characterized by means of UV-VIS, XRD, AAS, and HRTEM. FTIR CO adsorption studies provide evidence for Cu0 anchored at the titania surface by a characteristic absorption at 2084 cm-1. Comparative studies of Cu-deposition were performed using CuCl2 as simple Cu source which proved that the concept of organometallic disguise of the metal centre results in a higher reaction rate and the circumvention of non-selective reduction, parasitic side reactions and undesired agglomeration of the OLA stabilized titania nanorods.