In situ surface analysis of palladium-platinum alloys in methane oxidation conditions

Palladium and palladium-platinum foils were analysed using temperature-programmed near-ambient pressure x-ray photoelectron spectroscopy (TP-NAP-XPS) under methane oxidation conditions. Oxidation of palladium is inhibited by the presence of water, and in oxygen-poor environments. Pt addition further inhibits oxidation of palladium across all reaction conditions, preserving metallic palladium to higher temperatures. Bimetallic foils underwent significant restructuring under reaction conditions, with platinum preferentially migrating to the bulk under select conditions

Operando characterisation of alumina-supported bimetallic Pd–Pt catalysts during methane oxidation in dry and wet conditions

Near ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) was used to study the chemical states of a range of alumina-supported monometallic Pd and bimetallic Pd–Pt nanocatalysts, under methane oxidation conditions. It has been suggested before that for optimal complete methane oxidation, palladium needs to be in an oxidised state. These experiments, combining NAP-XPS with a broad range of characterisation techniques, demonstrate a clear link between Pt presence, Pd oxidation, and catalyst activity under stoichiometric reaction conditions. Under oxygen-rich conditions this behaviour is less clear, as all of the palladium tends to be oxidised, but there are still benefits to the addition of Pt in place of Pd for complete oxidation of methane

Crystal structure and Hirshfeld surface analysis of methyl 1-(2,4-dichlorobenzyl)-5-methyl-1H-pyrazole-3-carboxylate

The title compound, C13H12Cl2N2O2, crystallizes with six molecules in the asymmetric unit, such that, the 1H-pyrazole rings are essentially planar. The six molecules are stabilized by intramolecular C-H···N and C-H···Cl interactions and the crystal structure is stabilized by intermolecular C-H···O hydrogen bonds, forming molecular sheets into paralel to the (-1 1 0) plane. These sheets are connected to each other by C-H···O hydrogen bonds and C-H···π interactions. In the Hirshfeld surface analysis, the H···H, Cl···H/H···Cl, C···H/H···C, O···H/H···O, N···H/H···N, Cl···Cl, Cl···O/O···Cl interactions add to 95.8% of the intermolecular contacts of the Hirshfeld surface area. The remaining contributions (2.9%) correspond to Cl···C/C···Cl, C···O/O···C, O···O and N···N interactions. Crystal Data for C13H12Cl2N2O2 (M = 299.15 g/mol): Triclinic, space group P-1 (no. 2), a = 12.0505(10) Å, b = 12.3189(11) Å, c = 29.184(3) Å, α = 88.565(4)°, β = 89.296(4)°, γ = 76.833(4)°, V = 4217.0(7) Å3, Z = 12, T = 296(2) K, μ(MoKα) = 0.460 mm-1, Dcalc = 1.414 g/cm3, 83073 reflections measured (2.8° ≤ 2Θ ≤ 47°), 12426 unique (Rint = 0.0411, Rsigma = 0.0235) which were used in all calculations. The final R1 was 0.0662 (I > 2σ(I)) and wR2 was 0.2481 (all data)

Doping Agent Naphazoline Hydrochloride: Development of Simple and Fast Voltammetric Method for Its Determination in Human Serum

Electrochemical behavior of naphazoline hydrochloride on a carbon paste electrode that was modified with aluminium oxide nanoparticles (Al2O3NPs) was investigated in a Britton-Robinson (BR) buffer (pH 7.0) using various voltammetric techniques. The results support the presence of an irreversible and diffusion-controlled electrochemical oxidation signal of naphazoline hydrochloride which is approximately at 0.9 V vs. Ag/AgCl. A selective, accurate, and simple square-wave anodic adsorptive stripping voltammetric method was purposed for naphazoline hydrochloride detection. The linear response was within the range of 5.0 × 10-8- 3.0 × 10-5 mol L-1 with a detection limit of 2.6 × 10–8 mol L–1 (0.0064 mg L–1). In addition, the purposed method was also utilized for naphazoline hydrochloride determination in human serum sample

Crystal structure and Hirshfeld surface analysis of 1-(2,4-dichlorobenzyl)-5-methyl-N-(thiophene-2-sulfonyl)-1H-pyrazole-3-carboxamide

In the title compound, C16H13Cl2N3O3S2, the thiophene ring is disordered in a 0.762(3):0.238(3) ratio by an approximate 180 degrees rotation of the ring around the S-C bond linking the ring to the sulfonyl unit. The dichlorobenzene group is also disordered over two sets of sites with the same occupancy ratio. The molecular conformation is stabilized by intramolecular C-H center dot center dot center dot Cl and C-H center dot center dot center dot N hydrogen bonds, forming rings with graph-set notation S(5). In the crystal, pairs of molecules are linked by N-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds, forming inversion dimers with graph-set notation R-2(2)(8) and R-1(2)(11), which are connected by C-H center dot center dot center dot O hydrogen-bonding interactions into ribbons parallel to (100). The ribbons are further connected into a three-dimensional network by C-H center dot center dot center dot pi interactions and pi-pi stacking interactions between benzene and thiophene rings, with centroid-to-centroid distances of 3.865(2), 3.867 (7) and 3.853 (2) angstrom. Hirshfeld surface analysis has been used to confirm and quantify the supramolecular interactions

Piriformis Syndrome: Comparison of the Effectiveness of Local Anesthetic and Corticosteroid Injections: A Double-Blinded, Randomized Controlled Study

Background: Piriformis syndrome (PS), which is characterized by pain radiating to the gluteal region and posterior leg, is accepted as one of the causes of sciatalgia. Although the importance of local piriformis muscle injections whenever PS is clinically suspected has been shown in many studies, there are not enough studies considering the clinical efficacy of these injections

Optimisation by Design of Experiment of Benzimidazol-2-One Synthesis under Flow Conditions

A novel flow-based approach for the preparation of benzimidazol-2-one (1) scaffold by the 1,1 `-carbonyldiimidazole (CDI)-promoted cyclocarbonylation of o-phenylenediamine (2) is reported. Starting from a preliminary batch screening, the model reaction was successfully translated under flow conditions and optimised by means of design of experiment (DoE). The method allowed the efficient preparation of this privileged scaffold and to set up a general protocol for the multigram-scale preparation in high yield, purity, and productivity, and was successfully applied for the multigram flow synthesis of N-(2-chlorobenzyl)-5-cyano-benzimidazol-2-one, which is a key synthon for hit-to-lead explorations in our anti-inflammatory drug discovery program

Data for 'Combined in situ XAFS/DRIFTS studies of the evolution of nanoparticle structures from molecular precursors'

Data file for: Dann, E. et al (2017). Combined in situ XAFS/DRIFTS studies of the evolution of nanoparticle structures from molecular precursors. Chemistry of Materials Funded by EPSRC.</span

Combined in situ XAFS/DRIFTS Studies of the Evolution of Nanoparticle Structures from Molecular Precursors.

The rational design of catalyst materials is of great industrial significance, yet there is a fundamental lack of knowledge in some of the most well-established processes, e.g. formation of supported nanoparticle structures through impregnation. Here, the choice of precursor has a significant influence on the resulting catalytic properties of the end material, yet the chemistry that governs the transformation from defined molecular systems to dispersed nanoparticles is often overlooked. A spectroscopic method for advanced in situ characterization is employed to capture the formation of PdO nanoparticles supported on γ-Al2O3 from two alternative molecular precursors - Pd(NO3)2 and Pd(NH3)4(OH)2. Time-resolved diffuse reflectance infrared Fourier transform spectroscopy is able to identify the temperature assisted pathway for ligand decomposition, showing that NH3 ligands are oxidized to N2O and NO– species, whereas NO3– ligands assist in joining Pd centers via bidentate bridging coordination. Combining with simultaneous X-ray absorption fine structure spectroscopy, the resulting nucleation and growth mechanisms of the precious metal oxide nanoparticles are resolved. The bridging ability of palladium nitrate aids formation and growth of larger PdO nanoparticles at lower onset temperature (360 °C) for migration to form observable Pd–Pd distances of PdO nanoparticles. These smaller nanoparticles have improved dispersion and an increased number of step and edge sites compared to those formed from the conventional Pd(NO3)2 salt, favoring a lower light off temperature for complete methane oxidation