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We report on the synthesis of amphiphobic fluorinated surface‐active ionic liquid (FSAIL) epoxidation catalysts, which show reversible temperature‐controlled solubility in water. The solubility of FSAILs containing the catalytically active perrhenate‐ and tungstate anions was studied in both the aqueous and the substrate phase, showing a significant solubility decrease in both media compared to their non‐fluorinated congeners. It was shown that both the epoxide product and the catalyst additive phenylphosphonic acid (PPA) are efficient in transferring the FSAIL catalyst into the organic phase, rendering the reaction homogeneous. The FSAILs were used as catalysts for the epoxidation of olefins using aqueous H2O2 as oxidant, showing an exceptionally high catalytic activity at mild conditions. Catalyst recycling was demonstrated over ten consecutive runs by phase separation and subsequent product distillation. [ABSTRACT FROM AUTHOR]

The development of inexpensive and effective catalysts for the epoxidation of olefins to epoxides, which are key commodities for the chemical industry, is a continuing challenge. In this context, we present a supramolecular solution with the development of new host‐guest assemblies of sulfate ions and amidoammonium receptor cations that, for the first time, are shown to act as catalysts for olefin epoxidation by hydrogen peroxide under biphasic conditions. Analysis of the reaction mechanism shows that the reactive and oxidizing peroxymonosulfate is formed in the organic phase. Furthermore, a variety of readily available precursors may be used to form the supramolecular ion pairs (SIPs), which is enabling a large‐scale synthesis of the catalysts while maintaining catalytic control and effectiveness. [ABSTRACT FROM AUTHOR]

The bimetallic, decanuclear Ni3Ga7‐cluster of the formula [Ni3(GaTMP)3(μ2‐GaTMP)3(μ3‐GaTMP)] (1, TMP=2,2,6,6‐tetramethylpiperidinyl) reacts reversibly with dihydrogen under the formation of a series of (poly‐)hydride clusters 2. Low‐temperature 2D NMR experiments at −80 °C show that 2 consist of a mixture of a di‐ (2Di), tetra‐ (2Tetra) and hexahydride species (2Hexa). The structures of 2Di and 2Tetra are assessed by a combination of 2D NMR spectroscopy and DFT calculations. The cooperation of both metals is essential for the high hydrogen uptake of the cluster. Polyhydrides 2 are catalytically active in the semihydrogenation of 4‐octyne to 4‐octene with good selectivity. The example is the first of its kind and conceptually relates properties of molecular, atom‐precise transition metal/main group metal clusters to the respective solid‐state phase in catalysis. [ABSTRACT FROM AUTHOR]

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Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Vectorial catalysis—controlling multi‐step reactions in a programmed sequence and by defined spatial localization in a microscale device—is an enticing goal in bio‐inspired catalysis research. However, translating concepts from natural cascade biocatalysis into artificial hierarchical chemical systems remains a challenge. Herein, we demonstrate integration of two different surface‐anchored nanometer‐sized metal–organic frameworks (MOFs) in a microfluidic device for modelling vectorial catalysis. Catalyst immobilization at defined sections along the microchannel and a two‐step cascade reaction was conducted with full conversion after 30 seconds and high turnover frequencies (TOF≈105 h−1). [ABSTRACT FROM AUTHOR]

In order to explain the different catalytic activity in hydrogenation of two new intermetallic Ni/Ga clusters, [Ga7](NiCp*)6 (1A) and [NiGa6](NiCp*)6 (1B) (Cp* = C5Me5), investigations of structure–function relationship have been performed based on Raman and infrared (IR) spectroscopy and theoretical (density functional theory [DFT] and normal coordinate) calculations. Full interpretation of the Raman, far‐IR, and mid‐IR spectra of these dark colored solids has been proposed. Based on the overview of metal–Cp* complexes, all the 14 characteristic Cp*− skeletal fundamental modes have been identified. By comparison of the NiCp* stretching and tilting external modes (350–380 cm−1), their force constants, and bond lengths, cluster 1B exhibited slightly stronger metal–ligand bonding. Vibrations of Ga7 and NiGa6 cluster cores showed that the stretching wavenumbers and force constants of NiGa (100–350 cm−1) and GaGa (60–250 cm−1) bonds are higher for cluster 1B, in agreement with the shorter averaged experimental and calculated bond lengths of GaGa bonds (2.873 and 2823 Å for clusters 1A and 1B, respectively). Cluster hydrogenation experiments with H2 and D2 showed strong NiH and ND stretching features (at 1750 and 1260 cm−1, respectively), and at the same time, characteristic bands of self‐hydrogenated Cp*H and remained nondegraded clusters have been detected. The extent of HD exchange in cluster deuteration was obtained about 1.5 times more effective with cluster 1B than cluster 1A. The stronger hydrogen or deuterium uptake by cluster 1B and the more intensive self‐hydrogenation of Cp* clearly support the higher hydrogenation activity of cluster 1B compared with that of 1A. [ABSTRACT FROM AUTHOR]

The kinetics of cyclooctene epoxidation with H2O2 by micellar catalysis was studied. As catalyst, an ionic liquid (IL) containing the catalytically active tungstate anion was used. The tungstate IL forms micelles in the aqueous H2O2 phase. It is simply formed by dissolving sodium tungstate and 1‐octyl‐3‐methylimidazolium tetrafluoroborate [OMIM][BF4] in aqueous H2O2. For the epoxidation of cyclooctene by micellar catalysis, a power law kinetic model was determined that takes the critical micelle concentration into account. The kinetics of the [OMIM][BF4]/Na2WO4 catalyst is similar to pure [OMIM]2[WO4], which indicates that the active species is formed in situ. Addition of phenylphosphonic acid improves the activity of the tungstate IL. The most effective catalyst was tested in a semi‐continuous and continuous loop reactor. [ABSTRACT FROM AUTHOR]

In catalysis research the design of bio‐inspired,'artificial enzymes' is a field of huge interest. These catalysts are distinguished by their high catalytic efficiency resulting from a close proximity of several active sites and secondary substrate‐catalyst interactions enabled by functional groups in the catalytic pocket. A class of materials which meets these requirements are metal‐organic frameworks (MOFs). Here, the pores confine a reaction environment where several functionalities can be incorporated and spatially positioned in a tunable fashion. Recently, a number of reports revealed the importance of such confinement effects for the control of catalytic activity and selectivity by exploiting the intrinsic properties like pore size and neighboring group effects and the alignment and distance of different active sites within one MOF pore. Thus, this concept aims to accentuate the potential of the exploitation of those effects in MOFs for the design of sophisticated catalysts. [ABSTRACT FROM AUTHOR]

We report the hydrogenation catalytic activity application of molybdenum–ruthenium (MoRu) solid‐solution alloy nanoparticles (NPs) as catalysts for the hydrogenation of 1‐octene and 1‐octyne. The solid‐solution structure of MoRu NPs was confirmed through scanning transmission electron microscopy (STEM) coupled with energy‐dispersive X‐ray spectroscopy (EDX), and powder X‐ray diffraction (PXRD) measurement. The hydrogenation catalytic activity of these NPs toward 1‐octyne and 1‐octene in tetrahydrofuran (THF) was tested. The hydrogenation catalytic activity of Ru was enhanced by alloying with Mo at the atomic level. An electronic modification of Ru by a charge transfer from Mo to Ru, which could induce the change in the adsorption energy of reactants resulting in enhanced catalytic activity, was observed by X‐ray photoelectron spectroscopy. [ABSTRACT FROM AUTHOR]

We present the activation of hydrogen peroxide by micellar imidazolium nitrates via H-bond formation in water, as shown by vibrational spectroscopy and supported by DFT calculations. Mechanistic insight into the interactions of the surfactant cation, the nitrate anion and H2O2 is given. The micelles solubilise and epoxidise cyclooctene in the aqueous phase. [ABSTRACT FROM AUTHOR]

We present an overview of supramolecular strategies for epoxidations of hydrophobic olefins in water using phase-transfer-controlling surfactants, with special regard to the rationale of phase transfer and the efficiency of catalyst recycling. Principally, it is possible to transfer the catalyst to both the aqueous and the organic phase, depending on the type of surfactant and on the requirements for the reaction. We compare these two basic concepts with respect to the type of phase transfer and the supramolecular interactions between catalyst and surfactant, the catalyst activity, and the possibility for efficient and 'green' catalyst recycling. [ABSTRACT FROM AUTHOR]

We report on the influence of phosphanes on the catalytic activity and selectivity of colloidal, tetraoctylammonium bromide (TOAB) stabilised palladium nanoparticles (NPs) in the semi‐hydrogenation of alkynes to olefins. Full characterisation of the catalytic system (HRTEM, EDX, XPS, IR, NMR) confirmed the formation of spherical particles with a narrow size distribution (1.9±0.5 nm). The catalytic performance of the Pd NPs in the semi‐hydrogenation of 1‐octyne, 2‐octyne and phenylacetylene to the respective olefins and the influences on the selectivity was investigated. The system shows high activities and selectivities at mild conditions (0 °C and 1.0 bar H2 pressure). It was shown that generally, phosphanes lead to an increase of both the reaction rate and selectivity towards the olefin where both steric and electronic effects of the ligand play a crucial role for the catalyst performance. A moderate steric demand of the ligand with a rather weak σ‐donating ability turned out to give the highest catalytic performance. [ABSTRACT FROM AUTHOR]

The embedding of Ru nanoparticles into the otherwise unchanged metal-organic framework [[Zn.sub.4]O[(bdc).sub.3]] (MOF-5, bdc = 1,4-benzenedicarboxylate) is examined. Hydrogenolysis of the [[Ru(cod)(cot)].sub.3.5]@MOF-5 inclusion compound at the milder condition has not led to the formation of Ru nanoparticles.

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High oxygen reduction (ORR) activity has been for many years considered as the key to many energy applications. Herein, by combining theory and experiment we prepare Pt nanoparticles with optimal size for the efficient ORR in proton‐exchange‐membrane fuel cells. Optimal nanoparticle sizes are predicted near 1, 2, and 3 nm by computational screening. To corroborate our computational results, we have addressed the challenge of approximately 1 nm sized Pt nanoparticle synthesis with a metal–organic framework (MOF) template approach. The electrocatalyst was characterized by HR‐TEM, XPS, and its ORR activity was measured using a rotating disk electrode setup. The observed mass activities (0.87±0.14 A mgPt−1) are close to the computational prediction (0.99 A mgPt−1). We report the highest to date mass activity among pure Pt catalysts for the ORR within similar size range. The specific and mass activities are twice as high as the Tanaka commercial Pt/C catalysis. [ABSTRACT FROM AUTHOR]