X‐ray photoelectron spectroscopic chemical state quantification of mixed nickel metal,oxide and hydroxide systems

Quantitative chemical state X‐ray photoelectron spectroscopic analysis of mixed nickel metal, oxide, hydroxide and oxyhydroxide systems is challenging due to the complexity of the Ni 2p peak shapes resulting from multiplet splitting, shake‐up and plasmon loss structures. Quantification of mixed nickel chemical states and the qualitative determination of low concentrations of Ni(III) species are demonstrated via an approach based on standard spectra from quality reference samples (Ni, NiO, Ni(OH)₂, NiOOH), subtraction of these spectra, and data analysis that integrates information from the Ni 2p spectrum and the O 1s spectra. Quantification of a commercial nickel powder and a thin nickel oxide film grown at 1‐Torr O₂ and 300 °C for 20 min is demonstrated. The effect of uncertain relative sensitivity factors (e.g. Ni 2.67 ± 0.54) is discussed, as is the depth of measurement for thin film analysis based on calculated inelastic mean free paths. Copyright © 2009 John Wiley & Sons, Ltd.     

Pulsed EPR spectrometer with injection-locked UCSB free-electron laser

We describe the first free-electron laser (FEL)-based pulsed electron paramagnetic resonance (EPR) system designed to study spin dynamics and structure changes of proteins in aqueous solution with nano-second of time resolution. This novel approach opens up the possibility for high-power sub-THz and THz pulsed EPR spectroscopy.     

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ChemInform Abstract: A New n = 4 Layered Ruddlesden—Popper Phase K2.5Bi2.5Ti4O13 Showing Stoichiometric Hydration.

Polycrystalline K_2.5Bi_2.5Ti₄O₁₃ (I) is prepared by solid state reaction of KNO₃, Bi₂O₃, and TiO₂ (Al₂O₃ crucible, 750 °C, 16 h).     

Copper-catalyzed hydroamination of propargyl imidates

Propargyl imidates derived from aromatic and aliphatic nitriles cyclize at room temperature in high yields when treated with a catalytic amount of copper (I) iodide. This 5-exo-dig process affords dihydrooxazoles which do not aromatize under the reaction conditions, and which are isolated without chromatography. Investigations of the reaction scope, subsequent functionalization of the reaction products, and preliminary mechanistic data are presented.     

Computational study of fluoroquinolone binding to and its applicability to future drug design

Fluoroquinolones are an important therapeutic class in the targeting of new and resistant bacterial infections. Fluoroquinolones bind to bacterial type II topoisomerase via a water‐Mg²⁺ bridge. However, binding to magnesium‐containing molecules outside of the target cells increases the minimum inhibitory concentration (MIC) and promotes drug resistance. As a result, fluoroquinolones are counter‐indicated with magnesium and multivalent metal cation containing drugs, such as antacids. The antibiotic efficacy of fluoroquinolones has also been shown to be pH dependent, as we show the effect of protonation state on magnesium binding. This work presents a systematic computational study of fluoroquinolones' magnesium‐binding properties. We use B3LYP density functional theory and triple‐zeta basis sets, to evaluate binding affinities. Complexation is predicted to be thermodynamically favorable at neutral and basic compared to acidic pH. The calculated complexation energies broadly capture experimental binding affinities, suggesting this is a valid approach for designing new fluoroquinolones with a target magnesium binding affinity. We also investigate the effect of chemical substitution at the carboxylic acid to help in the identification of potential new antibiotics based on the fluoroquinolone pharmacophore.