Dynamic Coupling at the Ångström Scale

While momentum transfer from active particles to their immediate surroundings has been studied for both synthetic and biological micron‐scale systems, a similar phenomenon was presumed unlikely to exist at smaller length scales due to the dominance of viscosity in the ultralow Reynolds number regime. Using diffusion NMR spectroscopy, we studied the motion of two passive tracers—tetramethylsilane and benzene—dissolved in an organic solution of active Grubbs catalyst. Significant enhancements in diffusion were observed for both the tracers and the catalyst as a function of reaction rate. A similar behavior was also observed for the enzyme urease in aqueous solution. Surprisingly, momentum transfer at the molecular scale closely resembles that reported for microscale systems and appears to be independent of swimming mechanism. Our work provides new insight into the role of active particles on advection and mixing at the Ångström scale.     

Detoxification of Chemical Warfare Agents Using a Zr6‐Based Metal–Organic Framework/Polymer Mixture

Owing to their high surface area, periodic distribution of metal sites, and water stability, zirconium‐based metal–organic frameworks (Zr₆‐MOFs) have shown promising activity for the hydrolysis of nerve agents GD and VX, as well as the simulant, dimethyl 4‐nitrophenylphosphate (DMNP), in buffered solutions. A hurdle to using MOFs for this application is the current need for a buffer solution. Here the destruction of the simulant DMNP, as well as the chemical warfare agents (GD and VX) through hydrolysis using a MOF catalyst mixed with a non‐volatile, water‐insoluble, heterogeneous buffer is reported. The hydrolysis of the simulant and nerve agents in the presence of the heterogeneous buffer was fast and effective.     

Highly Phosphorescent Crystals of Square‐Planar Platinum Complexes with Chiral Organometallic Linkers: Homochiral versus Heterochiral Arrangements,Induced Circular Dichroism,and TD‐DFT Calculations

A novel class of chiral luminescent square‐planar platinum complexes with a π‐bonded chiral thioquinonoid ligand is described. Remarkably the presence of this chiral organometallic ligand controls the aggregation of this square planar luminophor and imposes a homo‐ or hetero‐chiral arrangement at the supramolecular level, displaying non‐covalent Pt–Pt and π–π interactions. Interestingly these complexes are highly luminescent in the crystalline state and their photophysical properties can be traced to their aggregation in the solid state. A TD‐DFT calculation is obtained to rationalize this unique behavior.     

Synthesis of the C12-C19 fragment of (+)-peloruside A through a diastereomer-discriminating RCM reaction

[reaction: see text]. A short and efficient asymmetric synthesis of the C12-C19 fragment of the cytotoxic macrolide (+)-peloruside A has been achieved via a highly diastereomer-discriminating RCM of alpha-branched but-3-enoate ester of a methallylic alcohol derived from hydrolytically resolved (S)-(-)-propylene oxide.     

Diasteroselective synthesis of new spiropiperidine scaffolds from the CN(R,S) building block

A methodology allowing the construction of spiropiperidine scaffolds similar to those found in naturally occurring alkaloids has been developed. This approach begins with the well-established CN(R,S) strategy, the spiro-center being built by way of an intramolecular attack of a nitrile function by an organolithium species obtained by a halogen/lithium exchange reaction mediated by either t-BuLi or lithium naphthalenide.     

Investigating the interaction of crystal violet probe molecules on sodium dodecyl sulfate micelles with hyper-Rayleigh scattering

We report the use of the nonlinear optical technique of hyper-Rayleigh scattering to investigate the interaction of the cationic probe molecule crystal violet with micelles of sodium dodecyl sulfate. An absolute value of (847 +/- 80) x 10(-30) esu is measured at the fundamental wavelength of 870 nm for the molecular hyperpolarizability of crystal violet free in pure aqueous solutions. In aqueous solutions of sodium dodecyl sulfate, above and below the critical micelle concentration, the measured hyperpolarizability of crystal violet is weaker than in the solution free of sodium dodecyl sulfate. From the comparison with linear optical photoabsorption spectroscopy data, this difference is attributed to electrostatic interactions between the cationic crystal violet molecules and the negatively charged sodium dodecyl sulfate surfactant molecules present in excess. Polarization resolved hyper-Rayleigh scattering measurements are then performed to show that, below and above the critical micelle concentration, crystal violet molecules also undergo symmetry changes upon interaction with sodium dodecyl sulfate. Above the critical micelle concentration, the minimum fraction of micelles interacting with at least one CV molecule is estimated. For instance, for a crystal violet aqueous concentration of 150 microM, this fraction is larger than 7%.     

Chromium (II) chloride : a new reagent for cross-aldol reactions

The proposed cross aldolization of α-bromoketones with aldehydes in presence of Chromium (II) chloride is an excellent stereospecific reaction. One exception to the stereospecific orientation is reported.     

Insights into electrochemical behavior and kinetics of NiP on PEDOT:PSS/reduced graphene oxide as high-performance electrodes for alkaline urea oxidation

Journal of Solid State Electrochemistry - Highly efficient, abundant, and low-cost materials are highly demanded for energy conversion applications to address the rising consumption of energy. In...     

Determination of hopane biomarkers in Arabian crude oils by gas chromatography-tandem mass spectrometry

Gas chromatography-mass spectrometry with the mass spectrometer operated in the tandem mode at a constant accelerating voltage was used to analyse for triterpanes in Arabian crude oils. Specific molecular parent-daughter ion pairs were selected for quantitative measurements owing to their metastable transitions in the first field-free region. More accurate relative distribution ratios of hydrocarbon biomarkers were determined by this sequential gating technique than by the conventional diagnostic daughter ion mass fragmentogram in common GC-MS. The data and spectra obtained from MS-MS operation may serve as unique “fingerprints” for these regional crudes