Fabrication and proton conductivity of sulfonated silica composites prepared by postoxidization of mercaptomethoxysilane

Sol–gel derived organic–inorganic hybrids containing phosphotungstic acid (PWA) have been prepared previously to obtain proton conductive membranes. However, leaking of PWA was a serious problem to achieve the higher proton conductivity. In this study, polyelectrolyte membranes functionalized with sulfonic acid groups were fabricated by the sol–gel method. Proton conductivity measurements were performed on an impedance analyzer at 80°C/95% RH. The functionalized polyelectrolyte membranes exhibited the proton conductivity σ ～ 0.9 (S/cm) which was much higher than the previously reported hybrids containing PWA. Although the hybrids exhibited fairly high proton conductivity irrespective to the catalysts used, that under the low relative humidity strongly depends on the catalysts. Among the hybrids prepared in this study, the membrane synthesized with HCl showed outstanding proton conductive properties even at the low humidity thanks to the proton transport channel formed by the swelling of ionic clusters. This fact was confirmed by measuring the ion exchange capacity, water uptake, swelling rate, Fourier transform infrared spectroscopy, atomic force microscopy, and thermogravimetric analysis. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Microscale Ionic Diodes: An Overview

Ionic rectifier membranes or devices generate uni-directional ion transport to convert an alternating current (AC) ion current input into stored energy or direct current (DC) in the form of ion/salt gradients. Electrochemical experiments 80 years ago were conducted on biological membrane rectifier systems, but today a plethora of artificial ionic rectifier types has been developed and electroanalytical tools are employed to explore mechanisms and performance. This overview focuses on microscale ionic rectifiers with a comparison to nano- and macroscale ionic rectifiers. The potential is surveyed for applications in electrochemical analysis, desalination, energy harvesting, electrochemical synthesis, and in selective ion extraction.     

A fully conservative high‐order upwind multi‐moment method using moments in both upwind and downwind cells

We propose a fully conservative high‐order upwind multi‐moment method for the conservation equation. The proposed method is based on a third‐order polynomial interpolation function and semi‐Lagrangian formulation and is a variant of the constrained interpolation profile conservative semi‐Lagrangian scheme with third‐order polynomial function method. The third‐order interpolation function is constructed based on three constraints in the upwind cell (two boundary values and a cell average) and a constraint in the downwind cell (a cell center value). The proposed method shows fourth‐order accuracy in a benchmark problem (sine wave propagation). We also propose a less oscillatory formulation of the proposed method. The less oscillatory formulation can minimize numerical oscillations. These methods were validated through scalar transport problems, and compressible flow problems (shock tube and 2D explosion problems). Copyright © 2016 John Wiley & Sons, Ltd.     

Anomalous electrical properties in superionic (Ag x Cu1−x )Br (x = 0.5): ab initio study

Ionics - The electrical properties of superionic (Ag x Cu1−x )Br (x = 0.5), band structure and density of states, have been examined by ab initio calculation based on the density...     

A Strategy toward Cyclic Topologies Based on the Dynamic Behavior of a Bis(hindered amino)disulfide Linker

A simple and efficient method to generate macrocyclic structures has been developed based on the dynamic behavior of the linker bis(2,2,6,6‐tetramethylpiperidin‐1‐yl)disulfide (BiTEMPS). The prime linear structure was transformed into a (macro)cycle using the following sequence: 1) thiol–ene reaction with a BiTEMPS derivative to afford the linear precursor, then 2) an entropy‐driven transformation induced by diluting and heating. The radicals generated from BiTEMPS upon heating are highly tolerant toward a variety of chemical species, including oxygen and olefins, but they exhibit high reactivity in exchange reactions, which can be applied to the topology transformation of various skeletons. The advantages of the present method, namely, its procedural simplicity and substrate versatility, are demonstrated by the gram‐scale synthesis of cyclic compounds with low and relatively high molecular weight.     

增长法在离域体系纳米线中的应用

本文综述了增长法这样一个原先起源于理论合成非周期性聚合物的方法。通过不同的体系验证了增长法高精度和高效率的特性。通过轨道漂移的处理手段,增长法能成功地应用到离域的p共轭体系。其处理手法是在增长过程中一些离域性特别强的分子轨道被重新指认到活性轨道中去,并与进攻的单元相互作用。增长法也可用来确定离域的卟啉线体系的非线性光学系数。     

Optical properties of Cr ion in lithium metasilicate Li2O · SiO2 transparent glass-ceramics

The optical properties of Cr³⁺ ions in lithium metasilicate (Li₂O · SiO₂) transparent glass-ceramics were investigated. The main crystalline phase precipitated was the lithium metasilicate (Li₂O · SiO₂) crystal. The percent crystallinity and crystalline size were ranging 65-75% and 20-35 nm, respectively. The color changes drastically to deep pink from emerald green upon crystallization. New and strong absorption bands appeared and the absorption intensity increases by about 10 times that in glass. These new absorption bands are found to be derived from Cr³⁺ ions in octahedral sites in the lithium metasilicate crystal lattice. Cr³⁺ ions substitute for three Li⁺ ions and occupy the distorted octahedral site between single [SiO₄]_n chains of lithium metasilicate crystal. The ligand field parameters can be estimated: 10Dq = 13 088 cm⁻¹, B = 453 cm⁻¹, Dq/B = 2.89 and C = 2036 cm⁻¹. The near-infrared luminescence centered at 1250 nm was not detected in the deep pink glass-ceramics unlike emerald green glass.     

Synthesis and Structure of Di-μ-oxo-bistripyrazolylborato Dioxo Vanadium (V) Complex with Lattice of Diacetonitrile

Abstract A novel oxovanadium complex was obtained by the reaction of VOSO₄ · 3H₂O with tripyrazolylborate sodium in MeOH. The complex (1) was characterized by element analysis, IR spectroscopy, ¹HNMR and its crystal for X-ray diffraction recrystallized from saturated CH₃CN solution. The compound crystallizes in the monoclinic, space group Pbca, with cell dimensions of a = 15.531(2) ?; b = 18.007(2) ?; c = 10.725(2) ?; V = 2,999.4(8) ?³ and D _calc = 1.533 g/cm³ for Z = 4. The structure was solved by direct methods and refined to an R-value of 0.0401. Structure analysis show that it is a di-μ-oxo-bistripyrazolylborato dioxo vanadium (V) complex with lattice of diacetonitrile. In addition, the electronic structure and the bonding characters of the complex were analyzed with ab initio calculations. Index Abstract Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.