A guide for the meaningful surface analysis of wood by XPS and ToF-SIMS

The surface analysis of wood and wood products is becoming increasingly important for reasons ranging from the investigation of molecular constituents through to the optimization of industrial processes. As with any natural product, wood analysis is not straightforward, and this review aims to provide guidance for the successful surface analysis of wood by XPS and ToF-SIMS. Through example experiments, three themes are addressed relevant to obtaining meaningful results: considerations related to heterogeneity in the composition of wood (e.g., growth rings); the impact of the chemical removal of minor wood components known as extractives, and whether such a process is necessary; and the potential for misleading or erroneous results as a result of contamination occurring during sample preparation. In addition to discussing successful sample preparation approaches, the important role to be played by MVA in surface analysis is emphasized, particularly in the analysis of ToF-SIMS data. Examples of ToF-SIMS/MVA are provided that highlight the identification of contamination in sample preparation, the quantification of wood composition in terms of cellulose and lignin, and the indication of age of softwood samples. Through consideration of the complexities that influence wood surface analysis, the design and interpretation of consequential experiments become easier and more accurate.     

FeIII in a high-spin state in bis(5-bromosalicylaldehyde 4-ethylthiosemicarbazonato-κ3O,N1,S)ferrate(III) nitrate monohydrate,the first example of such a cationic FeIII complex unit

The synthesis and crystal structure (100 K) of the title compound, [Fe(C₁₀H₁₁BrN₃OS)₂]NO₃·H₂O, is reported. The asymmetric unit consists of an octahedral [Fe^III(HL)₂]⁺ cation, where HL^? is H-5-Br-thsa-Et or 5-bromosalicylaldehyde 4-ethylthiosemicarbazonate(1?) {systematic name: 4-bromo-2-[(4-ethylthiosemicarbazidoidene)methyl]phenolate}, a nitrate anion and a noncoordinated water molecule. Each HL^? ligand binds via the thione S, the imine N and the phenolate O atom, resulting in an Fe^IIIS₂N₂O₂ chromophore. The ligands are orientated in two perpendicular planes, with the O and S atoms in cis and the N atoms in trans positions. This [Fe(HL)₂](anion)·H₂O compound contains the first known cationic Fe^III entity containing two salicylaldehyde thiosemicarbazone derivatives. The Fe^III ion is in the high-spin state at 100 K. In addition, a comparative IR spectroscopic study of the free ligand and the ferric complex is presented, demonstrating that such an analysis provides a quick identification of the degree of deprotonation and the coordination mode of the ligand in this class of metal compounds. The variable-temperature magnetic susceptibility measurements (5–320 K) are consistent with the presence of a high-spin Fe^III ion with a zero-field splitting D = 0.439 (1) cm^?1.     

Ideal cylindrical cloak: perfect but sensitive to tiny perturbations

A cylindrical wave expansion method is developed to obtain the scattering field for an ideal two-dimensional cylindrical invisibility cloak. A near-ideal model of the invisibility cloak is set up to solve the boundary problem at the inner boundary of the cloak shell. We confirm that a cloak with the ideal material parameters is a perfect invisibility cloak by systematically studying the change of the scattering coefficients from the near-ideal case to the ideal one. However, because of the slow convergence of the zeroth-order scattering coefficients, a tiny perturbation on the cloak would induce a noticeable field scattering and penetration.     

Crystallization of the $${\text{Mn}}^{{\text{II}}}[12{\text{-MC}}_{{\text{Mn}}^{{\text{III}}}{\text{(N)shi}}}{\text{-}}4]^{2+}$$ Mn II [ 12 -MC Mn III (N)shi - 4 ] 2 + Structure with 1,2,4-Triazolate from Methanol

Journal of Chemical Crystallography - The metallacrown (MC) dimer complex {MnII(OAc)(1,2,4-trz) $$[12{\text{-MC}}_{{\text{Mn}}^{{\text{III}}}{\text{(N)shi}}}{\text{-}}4]$$...     

Trinuclear Gold Clusters Supported by Cyclic (alkyl)(amino)carbene Ligands: Mimics for Gold Heterogeneous Catalysts

The synthesis of air‐ and moisture‐stable trinuclear mixed‐valence gold(I)/gold(0) clusters is described. They promote the catalytic carbonylation of amines under relatively mild conditions. The synthetic route leading to the trinuclear clusters involves a simple ligand exchange from the readily available μ³‐oxo‐[(Ph₃PAu)₃O]⁺ complex. This synthetic method paves the way for the preparation of a variety of mixed‐valence gold(I)/gold(0) polynuclear clusters. Moreover, the well‐defined nature of the complexes demonstrates that the catalytic process involves a rare example of a definite change of oxidation state of gold from Au⁰₂Au^I to Au^I₃.     

Strain Influences the Hydrogen Evolution Activity and Absorption Capacity of Palladium

Strain engineering can increase the activity and selectivity of an electrocatalyst. Tensile strain is known to improve the electrocatalytic activity of palladium electrodes for reduction of carbon dioxide or dioxygen, but determining how strain affects the hydrogen evolution reaction (HER) is complicated by the fact that palladium absorbs hydrogen concurrently with HER. We report here a custom electrochemical cell, which applies tensile strain to a flexible working electrode, that enabled us to resolve how tensile strain affects hydrogen absorption and HER activity for a thin film palladium electrocatalyst. When the electrodes were subjected to mechanically‐applied tensile strain, the amount of hydrogen that absorbed into the palladium decreased, and HER electrocatalytic activity increased. This study showcases how strain can be used to modulate the hydrogen absorption capacity and HER activity of palladium.     

Synthesis and Crystal Structure of MnII(OAc)2[15-MC MnIII(N)shi-5](Im)3(EtOH)3 (shi3??=?salicylhydroximate, ?OAc?=?acetate, Im?=?imidazole, and EtOH?=?ethanol)

Abstract  

The metallacrown complex Mn^II(OAc)₂[15-MC_Mn^III _(N)shi-5](Im)₃(EtOH)₃ has been synthesized and characterized by single-crystal X-ray diffraction and infrared spectroscopy. The compound crystallizes in the monoclinic space group P2₁/c with a = 24.3326(15) ?, b = 24.0354(15) ?, c = 27.0531(17) ?, α = 90.00°, β = 100.3883(11)°, γ = 90.00°, V = 15562.5(17) ?³, Z = 4, and Z′ = 2. Four of the five manganese(III) ions of the metallacrown ring adopt a distorted octahedral coordination geometry, and the fifth manganese(III) ion is five coordinate and exhibits a distorted square pyramidal environment. The configuration of the manganese(III) ions about the ring follows a pattern of ΔΛΔPP, with P representing planar. In addition, the imidazole units are bound to three separate ring manganese(III) ions, and the imidazole units are directed to the outside of the molecule. A manganese(II) ion is encapsulated in the central core of the molecule, and the central ion is seven coordinate with a face-capped trigonal prismatic geometry.     

Biotransformation-mediated synthesis of (1S)-1-(2,6-dichloro-3-fluorophenyl)ethanol in enantiomerically pure form

An efficient four-step biotransformation-mediated synthesis of (1S)-1-(2,6-dichloro-3-fluorophenyl)ethanol in enantiomerically pure form is described. This compound is a key intermediate required for the preparation of PF-2341066, a potent inhibitor of c-Met/ALK that is currently in clinical development. The described synthesis was used to manufacture 6 kg of the title compound and can also be employed to produce the corresponding (1R)-enantiomer.