Ionophore-Based Ion-Selective Electrodes in Non-Zero Current Modes: Mechanistic Studies and the Possibilities of the Analytical Application

Journal of Analytical Chemistry - This mini review briefly describes (i) literature data on the non-zero current measurements with ionophore-based ion-selective electrodes (ISEs) aimed at...     

Pd-catalyzed asymmetric reactions using resorcinol- and hydroquinone-based P∗,P∗-bidentate diamidophosphites

Readily available isomeric bisdiamidophosphites with P∗-stereocentres have been prepared using resorcinol and hydroquinone as simple and cheap starting materials. Palladium catalytic systems containing these P∗,P∗-bidentate ligands afforded 99% and 70% ees in asymmetric allylic substitution and desymmetrization processes, respectively. The influence of the precatalyst, substrate, nucleophile, and solvent on the enantioselectivity is discussed.     

Synthesis and properties of bi- and tricyclic 1,3-thiazoline/thiazolidine assemblies linked by an exocyclic С=С double bond

Chemistry of Heterocyclic Compounds - This review provides a generalized and systematized analysis of literature data from the last 15 years regarding the methods of synthesis and properties of bi-...     

Lone pairs mapping by Laplacian of 3He NMR chemical shift

Results of approbation of a new quantum mechanical approach of lone pairs (LPs) visualization, its optimization and testing on a range of model molecules are presented. The main idea of proposed methodology is using ³He atom as a probe for investigating electronic shells of species with LPs. As model objects, we consider “classical” examples of hydrogen cyanide, methanimine, ammonia, phosphine, formaldehyde, water, and hydrogen sulfide. It is shown that LPs can be visualized by means of 3D maps of Laplacian of ³He chemical shift ∇²δ_He. NMR calculations could be performed using level of theory as low as B3LYP/6-31G, allowing for the reduction of computational time without significant loss of quality. Advantages of our approach are discussed in comparison with usual methods of lone pairs visualization (electron localization function, molecular electrostatic potential).     

A Study of Strain Rate Effects for Turbulent Premixed Flames with Application to LES of a Gas Turbine Combustor Model

Large-scale strain rate field, a resolved quantity which is easily computable in large-eddy simulations (LES), could have profound effects on the premixed flame properties by altering the turbulent flame speed and inducing local extinction. The role of the resolved strain rate has been investigated in a posterior LES study of GE lean premixed dry low-NOx emissions LM6000 gas turbine combustor model. A novel approach which is based on the coupling of the linear-eddy model with a one-dimensional counterflow solver has been applied to obtain the parameterizations of the resolved premixed flame properties in terms of the reactive progress variable, the local strain rate measure, and local Reynolds and Karlovitz numbers. The strain rate effects have been analyzed by comparing LES statistics for several models of the turbulent flame speed, i.e, with and without accounting for the local strain rate effects, with available experimental data. The sensitivity of the simulation results to the inflow velocity conditions as well as the grid resolution have been also studied. Overall, the results obtained demonstrate that the effects of the resolved strain rate are not dominant for the considered premixed flame configuration and the unstrained turbulent flame speed model is found to perform as well as the one that allows for the strain rate effects.     

Improvement and analysis of computational methods for prediction of residual dipolar couplings

We describe a new, computationally efficient method for computing the molecular alignment tensor based on the molecular shape. The increase in speed is achieved by re-expressing the problem as one of numerical integration, rather than a simple uniform sampling (as in the PALES method), and by using a convex hull rather than a detailed representation of the surface of a molecule. This method is applicable to bicelles, PEG/hexanol, and other alignment media that can be modeled by steric restrictions introduced by a planar barrier. This method is used to further explore and compare various representations of protein shape by an equivalent ellipsoid. We also examine the accuracy of the alignment tensor and residual dipolar couplings (RDC) prediction using various ab initio methods. We separately quantify the inaccuracy in RDC prediction caused by the inaccuracy in the orientation and in the magnitude of the alignment tensor, concluding that orientation accuracy is much more important in accurate prediction of RDCs.     

C80Cl12: A Chlorine Derivative of the Chiral D2‐C80 Isomer—Empirical Rationale of Halogen‐Atom Addition Pattern

Welcome to the family! The constitution of the chiral D₂‐C₈₀ fullerene has been confirmed through single‐crystal X‐ray analysis of the chlorinated C₈₀Cl₁₂. The addition pattern of the chlorine atoms in the structure of C₈₀Cl₁₂ together with other structures of halogenated higher fullerenes is discussed. A stepwise principle of higher fullerene reactivity is proposed. Unusual short intermolecular chlorine–chlorine contacts are reported.