Asymmetric organocatalytic synthesis of cyclopentane γ-nitroketones

This paper describes the use of bifunctional thiourea catalysts in the intramolecular reaction of a nitronate with conjugated ketones to generate the corresponding γ-nitroketones. In contrast to our previous studies in this area, we obtained the cis-functionalized systems as the major diastereoisomers in good yields and reasonable selectivities.

'Nature concocts & expels': the agents and processes of recovery from disease in Early Modern England

The ‘golden saying’ in early modern medicine was ‘Nature is the healer of disease’. This article uncovers the meaning and significance of this forgotten axiom by investigating perceptions of the agents and physiological processes of recovery from illness in England, c.1580-1720. Drawing on sources such as medical texts and diaries, it shows that doctors and laypeople attributed recovery to three agents – God, Nature, and the practitioner. While scholars are familiar with the roles of providence and medicine, the vital agency of Nature has been overlooked. In theory, the agents operated in a hierarchy: Nature was ‘God’s instrument’, and the physician, ‘Nature’s servant’; but in practice the power balance was more ambivalent. Nature was depicted both as a housewife who cooked and cleaned the humours, and as a warrior, who defeated the disease. Through exploring these complex dynamics, the article sheds fresh light on concepts of gender, disease, and bodies.

Role of ligands in catalytic water oxidation by mononuclear ruthenium complexes

Since first reported in 2005, mononuclear ruthenium water oxidation catalysts have attracted a great deal of attention due to their catalytic performance and synthetic flexibility. In particular, ligands coordinated to a Ru metal centre play an important role in the catalytic mechanisms, exhibiting significant impact on catalyst efficiency, stability and activity towards water oxidation. This review focuses on finding possible correlations between the ligand effects and activity of mononuclear Ru aqua and non-aqua complexes as water oxidation catalysts. The ligand effects highlighted in the text include the electronic nature of core ligands and their substituents, the trans–cis effect, steric hindrance and the strain effect, the net charge effect, the geometric arrangement of the aqua ligand and the supramolecular effects, e.g., hydrogen bonding and influence of a pendant base. The outcome is not always obvious at the present knowledge level. Deeper understanding of the ligand effects, based on new input data, is mandatory for further progress towards a rational development of novel catalysts featuring enhanced activity in water oxidation.

Surface chemistry of alanine on Ni{111}

The adsorption of L-alanine on Ni{111} has been studied as a 10 model of enantioselective heterogeneous catalysts. Synchrotron-based X-ray 11 photoelectron spectroscopy and near-edge X-ray absorption fine structure 12 (NEXAFS) spectroscopy were used to determine the chemical state, bond 13 coordination, and out-of-plane orientation of the molecule on the surface. 14 Alanine adsorbs in anionic and zwitterionic forms between 250 and ≈320 K. 15 NEXAFS spectra exhibit a strong angular dependence of the π* resonance 16 associated with the carboxylate group, which is compatible with two distinct 17 orientations with respect to the surface corresponding to the bidentate and 18 tridentate binding modes. Desorption and decomposition begin together at 19 ≈300 K, with decomposition occurring in a multistep process up to ≈450 K. Comparison with previous studies of amino acid 20 adsorption on metal surfaces shows that this is among the lowest decomposition temperatures found so far and lower than typical 21 temperatures used for hydrogenation reactions where modified Ni catalysts are used.

The partial oxidation of methane over Pd/Al2O3 catalyst nanoparticles studied in-situ by near ambient-pressure x-ray photoelectron spectroscopy

Near ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) is used to study the chemical state of methane oxidation catalysts in-situ. Al2O3{supported Pd catalysts are prepared with different particle sizes ranging from 4 nm to 10 nm. These catalysts were exposed to conditions similar to those used in the partial oxidation of methane (POM) to syn-gas and simultaneously monitored by NAP-XPS and mass spectrometry. NAP-XPS data show changes in the oxidation state of the palladium as the temperature in- creases, from metallic Pd0 to PdO, and back to Pd0. Mass spectrometry shows an increase in CO production whilst the Pd is in the oxide phase, and the metal is reduced back under presence of newly formed H2. A particle size effect is observed, such that CH4 conversion starts at lower temperatures with larger sized particles from 6 nm to 10 nm. We find that all nanoparticles begin CH4 conversion at lower temperatures than polycrystalline Pd foil.