Mohrbroch3470

Direct carbonylation of the C-H bond is a great tool for installing a carbonyl group in a wide variety of substrates. This review summarizes the C-H bond carbonylation methodologies using the cobalt-catalyzed C-H bond functionalization approach. Despite the fact that cobalt-catalyzed carbonylation methodologies have been known since Murahashi's report in 1955, this area is still underdeveloped, particularly carbonylation of the C(sp3)-H bond.Water diffusion in polymer composites is not only affected by the chemical nature of the materials but also by their internal structures. selleck products To enable the design of polymer composites with controlled diffusion kinetics, we investigate the effect of hydrogel particle networks on the water transport. The composites in this study comprise hydrogel particles based on sodium poly(acrylic acid), which are incorporated at different concentrations into a soft and sticky polymer matrix. Through the use of X-ray micro computed tomography, the internal structure of the polymer composites is examined and the interparticle distances are calculated. The structure of the composites is then related to the water diffusion kinetics upon exposure to saline solution as well as humid air. Even though the hydrogel particles are isolated and the interparticle distances are in the order of several micrometers, a sudden increase in the water diffusion kinetics is observed above a critical concentration. Due to the low water permeability of the matrix, such a change in the water diffusion kinetics is indicative of network formation. During hydration, swelling enables the hydrogels to overcome the interparticle distances and form a network for water transport.Amino acid stereoconfiguration has been shown to play a key role in the self-assembly of unprotected tripeptides into hydrogels under physiological conditions. Dramatic changes were noted for hydrophobic sequences based on the diphenylalanine motif from the formation of amorphous aggregates in the case of homochiral peptides to nanostructured and stable hydrogels in the case of heterochiral stereoisomers. Herein, we report that by further shortening the sequence to a dipeptide, the overall differences between isomers are less marked, with both homo- and hetero-chiral dipeptides forming gels, although with different stability over time. The soft materials are studied by a number of spectroscopic and microcopic techniques, and single-crystal X-ray diffraction to unveil the supramolecular interactions of these hydrogel building blocks.Adhesion of bacteria to liquid-liquid interfaces can play a role in the biodegradation of dispersed hydrocarbons and in biochemical and bioprocess engineering. Whereas thermodynamic factors underpinning adhesion are well studied, the role of bacterial activity on adhesion is less explored. Here, we show that bacterial motility enhances adhesion to surfactant-decorated oil droplets dispersed in artificial sea water. Motile Halomonas titanicae adhered to hexadecane droplets stabilized with dioctyl sodium sulfosuccinate (DOSS) more rapidly and at greater surface densities compared to nonmotile H. titanicae, whose flagellar motion was arrested through addition of a proton uncoupler. Increasing the concentration of DOSS reduced the surface density of both motile and nonmotile bacteria as a result of the reduced interfacial tension.The response of the electronic properties of the HfN2 monolayer to external perturbation, such as strain and electric fields, has been extensively investigated using density functional theory calculations for its device-based applications and photocatalysis. The HfN2 monolayer is found to be a semiconductor showing a direct band gap of 1.44 eV, which is widely tunable by 0.9 eV via application of biaxial strain. Furthermore, the tunability in the band edges of the HfN2 monolayer straddling the water redox potential under a biaxial strain of ±10% makes it suitable for solar energy harvesting via photocatalytic applications over a wide range (0-7) of pH. The band gap can be decreased by 29.8% under a biaxial tensile strain of 10%. Upon incorporation of spin orbit coupling (SOC) a large spin splitting at the conduction band (Δc ∼ 314 meV) and a small splitting at the valence band (Δv ∼ 32 meV) are noted, which is attributable to the orbital composition of the band edges. The spin splitting in the band edges is fctron Gas) states. A HfN2 monolayer based tunnel field effect transistor (t-FET) is proposed herewith as a model device for low-power digital data storage, thereby paving new avenues in flexible electronics and memory devices.The intramolecular N-Boc-epoxide cyclization leading to the formation of 1,3-oxazolidin-2-one and 1,3-oxazinan-2-one derivatives has scarcely been reported in the literature. More specifically, the intramolecular cyclization of N-Boc aniline-tethered 2,3-disubstitued epoxides has never been disclosed. Herein, we demonstrate that this reaction could proceed in a diastereoselective fashion in refluxing trifluoroethanol, in the absence of any external promoter or catalyst. Substrates bearing an alkyl group at the C-3 position furnished 1,3-oxazolidin-2-ones in a completely regioselective fashion via 5-exo epoxide ring-opening cyclization, thereby paving the way to synthesize alkyl side chain-bearing analogs of the antidepressant drug toloxatone. On the other hand, replacing the alkyl group with an aryl group resulted in easily separable mixtures of 1,3-oxazolidin-2-ones and 1,3-oxazinan-2-ones, the former being obtained as the major products. Remarkably, a tetralin-bearing substrate underwent fully regioselective 6-endo ring closure to form the corresponding 1,3-oxazinan-2-one. Our present study on the intramolecular ring opening-cyclization of epoxides with a tethered N-Boc group is the most comprehensive to date and features broad substrate scope, mild transition metal-free conditions, excellent functional group tolerance, and scalability.Fibrin is the major extracellular component of blood clots and a proteinaceous hydrogel used as a versatile biomaterial. Fibrin forms branched networks built of laterally associated double-stranded protofibrils. This multiscale hierarchical structure is crucial for the extraordinary mechanical resilience of blood clots, yet the structural basis of clot mechanical properties remains largely unclear due, in part, to the unresolved molecular packing of fibrin fibers. Here the packing structure of fibrin fibers is quantitatively assessed by combining Small Angle X-ray Scattering (SAXS) measurements of fibrin reconstituted under a wide range of conditions with computational molecular modeling of fibrin protofibrils. The number, positions, and intensities of the Bragg peaks observed in the SAXS experiments were reproduced computationally based on the all-atom molecular structure of reconstructed fibrin protofibrils. Specifically, the model correctly predicts the intensities of the reflections of the 22.5 nm axial repeat, corresponding to the half-staggered longitudinal arrangement of fibrin molecules. In addition, the SAXS measurements showed that protofibrils within fibrin fibers have a partially ordered lateral arrangement with a characteristic transverse repeat distance of 13 nm, irrespective of the fiber thickness. These findings provide fundamental insights into the molecular structure of fibrin clots that underlies their biological and physical properties.Quasi-static tensile experiments were performed for a model disordered solid consisting of a two-dimensional raft of polydisperse floating granular particles with capillary attractions. The ductility is tuned by controlling the capillary interaction range, which varies with the particle size. During the tensile tests, after an initial period of elastic deformation, strain localization occurs and leads to the formation of a shear band at which the pillar later fails. In this process, small particles with long-ranged interactions can endure large plastic deformation without forming significant voids, while large particles with short-range interactions fail dramatically by fracturing at small deformation. Particle-level structure was measured, and the strain-localized region was found to have higher structural anisotropy than the bulk. Local interactions between anisotropic sites and particle rearrangements were the main mechanisms driving strain localization and the subsequent failure, and significant differences of such interactions exist between ductile and brittle behaviors.Density functional theory (DFT) calculations have been carried out to investigate the performance of borophosphene in lithium-ion batteries. Our study has revealed the following (1) the Dirac cone in the electronic structure demonstrates the metallic nature of borophosphene, implying the enhanced electronic conductivity of the anode electrodes; (2) borophosphene shows high adsorption of Li ions with binding energies in the range of -0.6 to -1.1 eV; (3) the theoretical storage capacity is significantly high, up to 1282.7 mA h g-1, and more interestingly, a structural transition is observed in the host borophosphene at a high density of Li ions; (4) at low concentrations, graphene-like borophosphene shows isotropic diffusion of Li atoms with a barrier around 0.5 eV, while at high density, the phosphorene-like borophosphene exhibits a reduced barrier in the range of 0.12-0.14 eV along the zigzag direction, suggesting strong promotion of Li-ion transportation; (5) meanwhile, owing to the structural transition, phosphorene-like borophosphene exhibits highly anisotropic migration of Li ions along the zigzag and armchair directions. These new findings present the great advantages of borophosphene as an anode material in lithium-ion batteries.Recent studies of low-valent main group species underscore their resemblance to transition metal complexes with regards to the ability to activate small molecules. Here, we report synthesis and full characterisation of the persistent (hypersilyl)(pentamethylcyclopentadienyl)silylene Cp*[(Me3Si)3Si]Si as well as its unique reactivity. Silylene Cp*[(Me3Si)3Si]Si activates dihydrogen to give the corresponding dihydrosilane Cp*[(Me3Si)3Si]SiH2 at particularly mild conditions as well as ethylene to afford the three-membered cyclic silirane c-Cp*[(Me3Si)3Si]Si(H2CCH2). The addition of N-heterocyclic carbene NHC (NHC = 1,3,4,5-tetramethyl-imidazol-2-ylidene) to dihydrosilane Cp*[(Me3Si)3Si]SiH2 induces the reductive elimination of Cp*H, which according to DFT calculations is thermodynamically preferred over H2 elimination. With NHC, Cp*[(Me3Si)3Si]Si forms a typical donor-acceptor complex with concomitant change in hapticity of the Cp* ligand from η2 to η1 (σ). In contrast, the reaction with the N-heterocyclic silylene c-[(CH[double bond, length as m-dash]CH(tBuN)2]Si leads to an unusual "masked" disilene with the former Cp* ligand bridging the two silicon centres. The heterodimer is stable in the solid state, but dissociates reversibly to the constituting silylene fragments in solution.Droplet microfluidics systems hold great promise in their ability to conduct high-throughput assays for a broad range of life science applications. Despite their promise in the field and capability to conduct complex liquid handling steps, currently, most droplet microfluidic systems used for real assays utilize only a few droplet manipulation steps connected in series, and are often not integrated together on a single chip or platform. This is due to the fact that linking multiple sequential droplet functions within a single chip to operate at high efficiency over long periods of time remains technically challenging. Considering sequential manipulation is often required to conduct high-throughput screening assays on large cellular and molecular libraries, advancements in sequential operation and integration are required to advance the field. This current limitation greatly reduces the type of assays that can be realized in a high-throughput droplet format and becomes more prevalent in large library screening applications.