Davidankersen1483

In particular, while the niobium compound displays evidence for redox-trapping and strong magnetic interactions, the molybdenum phase is valence-delocalized with evidence of large polaron formation. Weak interlayer interactions in the neutral molybdenum phase enable solvent-assisted exfoliation to yield few-layer hexagonal nanosheets. Together, these results represent the first syntheses of metal-organic frameworks containing mononuclear niobium and molybdenum nodes, establishing a route to frameworks incorporating a more diverse range of second- and third-row transition metals with increased covalency and the potential for improved charge transport and stronger magnetic coupling.The study of metal phosphide catalysts for organic synthesis is rare. We present, for the first time, a well-defined nano-cobalt phosphide (nano-Co2P) that can serve as a new class of catalysts for the hydrogenation of nitriles to primary amines. While earth-abundant metal catalysts for nitrile hydrogenation generally suffer from air-instability (pyrophoricity), low activity and the need for harsh reaction conditions, nano-Co2P shows both air-stability and remarkably high activity for the hydrogenation of valeronitrile with an excellent turnover number exceeding 58000, which is over 20- to 500-fold greater than that of those previously reported. Moreover, nano-Co2P efficiently promotes the hydrogenation of a wide range of nitriles, which include di- and tetra-nitriles, to the corresponding primary amines even under just 1 bar of H2 pressure, far milder than the conventional reaction conditions. read more Detailed spectroscopic studies reveal that the high performance of nano-Co2P is attributed to its air-stable metallic nature and the increase of the d-electron density of Co near the Fermi level by the phosphidation of Co, which thus leads to the accelerated activation of both nitrile and H2. Such a phosphidation provides a promising method for the design of an advanced catalyst with high activity and stability in highly efficient and environmentally benign hydrogenations.Direct analyses of crude reaction mixtures have been carried out using molecular rotational resonance (MRR) spectroscopy. Two examples are presented, a demonstration application in photocatalytic CH-arylation as well as generation of an intermediate in a natural product synthesis. In both cases, the reaction can proceed at more than one site, leading to a mixture of regioisomers that can be challenging to distinguish. MRR structural parameters were calculated for the low lying conformers for the desired compounds, and then compared to the experimental spectra of the crude mixtures to confirm the presence of these species. Next, quantitation was performed by comparing experimentally measured line intensities with simulations based on computed values for the magnitude and direction of the molecular dipole moment of each species. This identification and quantification was performed without sample purification and without isolated standards of the compounds of interest. The values obtained for MRR quantitation were in good agreement with the chromatographic values. Finally, previously unknown impurities were discovered within the photocatalytic CH-arylation work. This paper demonstrates the utility of MRR as a reaction characterization tool to simplify analytical workflows.Ion transport across lipid bilayer membranes in biology is controlled by membrane proteins, which in turn are regulated in response to chemical-, physical- and photo-stimuli. The design of synthetic supramolecular ion transporters able to be precisely controlled by external signals, in particular bio-compatible wavelengths of visible light, is key for achieving spatio-temporal control over function. Here we report two-colour responsive molecular photo-switches that act as supramolecular transmembrane anion carriers. Reversible switching of the photo-switch within the lipid bilayer membrane is achieved using biocompatible visible wavelengths of light, such that temporal control over transmembrane anion transport is achieved through alternating irradiation with red and blue light.We detail a strategy that uses a commercially available nucleophilic organic catalyst to generate acyl and carbamoyl radicals upon activation of the corresponding chlorides and anhydrides via a nucleophilic acyl substitution path. The resulting nucleophilic radicals are then intercepted by a variety of electron-poor olefins in a Giese-type addition process. The chemistry requires low-energy photons (blue LEDs) to activate acyl and carbamoyl radical precursors, which, due to their high reduction potential, are not readily prone to redox-based activation mechanisms. To elucidate the key mechanistic aspects of this catalytic photochemical radical generation strategy, we used a combination of transient absorption spectroscopy investigations, electrochemical studies, quantum yield measurements, and the characterization of key intermediates. We identified a variety of off-the-cycle intermediates that engage in a light-regulated equilibrium with reactive radicals. These regulated equilibriums cooperate to control the overall concentrations of the radicals, contributing to the efficiency of the overall catalytic process and facilitating the turnover of the catalyst.Metal oxides are widely used in different fields, including photoelectrocatalysis, photocatalysis, dye-sensitized solar cells, photoinduced superhydrophilicity and so on. It is well-known that there are intrinsic hydrated layers on the surfaces of metal oxides in ambient air or the electrolyte. Generally, interface layers between metal oxides and solutions have significant effects on the performances in these applications. However, the exact roles of the intrinsic hydrated layers are still unclear. In this study, taking TiO2 and Fe2O3 as model materials, we propose a mild heat treatment to increase the hydroxyl concentration in the hydrated surface layers of the oxides, which improves their photoelectrochemical performance remarkably. Moreover, we find that the heat-regulated hydrated layer plays the role of a hole transfer mediator between oxides and the electrolyte, which can accelerate both interface charge collection and oxygen evolution reaction kinetics in acidic solution. The new insights into the intrinsic hydrated interface layer on oxides can offer guidance not only in photoelectrocatalysis, but also in the other applications mentioned above.