Influence of the Metal Nature on the EDL Structure in Propylene Carbonate Solutions of a Surface-Inactive Electrolyte

The curves of differential capacitance and potentials of zero charge of Ga, In–Ga, and Tl–Ga electrodes in propylene carbonate (PC) solutions of a surface-inactive electrolyte are obtained. It is shown that PC is chemically indifferent to these electrodes, mainly because of a lower electron donor ability of its molecules. A metal–PC chemisorption interaction slightly depends on the metal nature and increases in the series Hg = (Tl–Ga) < (In–Ga) < Ga.     

Electroreduction of Oxalate Complexes of Ruthenium(III) on a Dropping Mercury Electrode: Effect of Alkali Metal Cations and Solution Acidity

It is established that the reaction of recharging trioxalate complexes of ruthenium(III) occurs in the case of solutions with excess supporting oxalate salts of alkali metals K⁺, Na⁺, and Cs⁺ in reversible conditions, and limiting recharge currents are caused by diffusion. At the same time, values of diffusion coefficients for complex anion [Ru(C₂O₄)₃]^–3 decrease by almost two times upon going from potassium to sodium and cesium electrolytes. Substantial differences in the limiting currents in solutions containing excess amounts of the above salts are explained by the formation, at least in the case of cesium and sodium electrolytes, of ionic associates whose reduction rate at a fixed potential is lower than that of nonassociated anion [Ru(C₂O₄)₃]^–3. With solution dilution by supporting salts, transition is observed from reversible recharge conditions to absolutely irreversible conditions and a change in the above sequence of the effect of supporting cations on the recharge rate; at a fixed potential, the process decelerates in the series Cs⁺ > K⁺ > Na⁺. The reduction wave of the ruthenium(II) oxalate complexes in solutions with excess supporting electrolyte happens to depend on pH and, probably, is determined by simultaneous formation of adsorbed atoms of hydrogen (or ruthenium hydride) on atoms of ruthenium(0).     

Relationship between the Physicochemical Properties of Electrolytes and the Electronic Structure of Solvated Alkali Metal Cations

Group theoretical analysis and linear combinations of molecular orbitals of the cation and solvent are used to establish the nature and stability of bonds and hence the electric mobility of the cation and the viscosity of the electrolyte depending on the type of cation (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺) and molecules (H₂O, NH₃, H₂CO, (CH₃)₂CO, CH₃CN). Solvation effects on the UV photoelectron and intramolecular vibrational IR and NMR spectra are revealed.     

Effect of Alkali Metal Cations on Length and Strength of Hydrogen Bonds in DNA Base Pairs

For many years, non-covalently bonded complexes of nucleobases have attracted considerable interest. However, there is a lack of information about the nature of hydrogen bonding between nucleobases when the bonding is affected by metal coordination to one of the nucleobases, and how the individual hydrogen bonds and aromaticity of nucleobases respond to the presence of the metal cation. Here we report a DFT computational study of nucleobase pairs interacting with alkali metal cations. The metal cations contribute to the stabilization of the base pairs to varying degrees depending on their position. The energy decomposition analysis revealed that the nature of bonding between nucleobases does not change much upon metal coordination. The effect of the cations on individual hydrogen bonds were described by changes in VDD charges on frontier atoms, H-bond length, bond energy from NBO analysis, and the delocalization index from QTAIM calculations. The aromaticity changes were determined by a HOMA index.     

Effect of Adsorption of Neutral Molecules on the EDL Capacitance of a Rough Electrode

The perturbation theory is used to design a theoretical model for the Frumkin–Melik-Gaikazyan impedance of a sine electrode with a perturbation parameter equal to the ratio between the amplitude of surface oscillations and its period for a diffusion-controlled adsorption stage. The unequal diffusion access to the interface increases its capacitance. At higher frequencies, the electrode capacitance is defined by its geometric roughness factor. At lower frequencies, the capacitance depends on the adsorption conditions. The adsorption of electroactive substances results in a constant phase angle; the electrode roughness alters it and the frequency range where it remains constant.     

NH4OH-TBAOH体系中碱金属离子对硅沸石生成的影响

本文研究了NH₄OH-TBAOH体系碱金属离子对硅沸石-2生成时晶型转化、晶胞组成、晶体大小和形貌等方面的影响规律.     

Selective Transport of Alkali Metal Cations in Solvent Extraction by Proton-Ionizable Dibenzocrown Ethers

Abstract

Lipophilic crown ethers with pendant proton-ionizable groups are novel metal complexing agents for use in solvent extraction of alkali metal cations. A variety of dibenzocrown ether carboxylic acids and dibenzo crown phosphonic acid monoesters have been examined to probe the effect of structural variation within the complexing agent upon selectivity and efficiency in solvent extraction. Results from competitive solvent extractions of alkali metal cations from aqueous solutions into chloroform are summarized.     

Synthesis and Crystal Structure of A New Armed-tetraazacrown Ether and Its Liquid Membrane Transport of Alkali Metal Cations

Introduction　　Transportofcationsacrossanorganicliquidmem branewhichseparatestwowaterphaseshasbeenexten sivelyinvestigated .1Thesyntheticmacrocyclicligands ,suchascrownethers ,areusuallyusedasmodelcarrierstomimicthenaturallyoccurringantibioticmacrocycleswhichhavebeenshowntoalterthepermeabilityofbiologicalmembranestocertaincations .2 ,3 Thus ,theyhaveimpor tantapplicationsinbothchemistryandbiologytoselectivecomplexationofvariousmetalcations .4 ,5Itwasreportedthatthedivalenttransition metalcomp…     

The Effect of Water Addition on the Electrosurface Properties of Quartz in Solutions of Alkali Metal Bromides in Ethanol

Electrosurface properties (the -potential and surface conductivity) of quartz particles in water–ethanol solutions of CsBr, NaBr, and LiBr with concentrations C = 10^–5–10^–2 M are studied. The (log C) dependences plotted from the results of electrophoretic measurements with allowance made for the particle surface conductivity demonstrate that, when water content in the aforementioned solutions increases from 4 to 40 vol %, the -potential of quartz becomes more negative and the isoelectric point shifts toward higher electrolyte concentrations, which increase in the following series: CsBr < NaBr < LiBr. This shift of the isoelectric point is explained by a decrease in the specific interaction of the alkali metal cations with the quartz surface because of a rise in the degree of their hydration (supersolvation).     

肌醇在碱金属氯化物溶液中的体积性质

使用精密数字密度计测定了298.15和308.15 K肌醇在不同浓度的LiCl-H2O、NaCl-H2O或KCl-H2O溶液中的密度, 计算了肌醇的表观摩尔体积Vφ和极限偏摩尔体积Vθφ , 得到了其由纯水溶剂转移至混合溶剂中的迁移偏摩尔体积⊿trsVθ椎 .结果表明, LiCl, NaCl和KCl在溶液中对肌醇的体积性质影响显著, 极限偏摩尔体积Vθφ和极限迁移偏摩尔体积⊿trsVθφ都随盐浓度的增大而增加;温度对肌醇的极限偏摩尔体积和极限迁移偏摩尔体积只有轻微影响. 从分子-离子间的相互作用角度对实验结果进行了讨论.     

Decomposition Kinetics of Alkali Metal Gallams in Hydroxide Aqueous Solutions

The decomposition kinetics of alkali metal gallams in LiGa-LiOH, NaGa-NaOH, KGa-KOH, LiGa-NaOH, LiGa-KOH, and KGa-NaOH systems in the 40-80°C range was studied. The rate constant and current density of decomposition were determined. The rate equation of gallam decomposition under the given experimental conditions was obtained.     

The Effects of Alkali Metal Cations on Product Distributions in Cucurbit[n]uril Synthesis

The synthesis of new cryptands containing 1-methyl or 1-hexadecyl-pyrazole is described in high yield using metal templated [3+2] tripodal condensation.     

Adsorption of Complexes of Cations of Alkali Metals with a Macrocyclic Ligand (Kryptofix® 222) on a Mercury Electrode

Adsorption of complexes of alkali metal cations with a macrocyclic ligand (C₁₈H₃₆N₂O₆, Kryptofix® 222) is studied as a function of their concentration by measuring the differential capacitance on a stationary mercury drop. The complexes (kryptates) possess a high adsorption capability. The adsorption parameters of sodium kryptate are found within a model of two parallel capacitors complemented by a Frumkin adsorption isotherm. Curves of the differential capacitance and the electrocapillary curves, calculated from these parameters, nicely conform to the experimental data obtained in this work and to the literature data.     

DFT Study for a Series of Less-Symmetrical Crown Ethers and Their Complexes with Alkali Metal Cations

A series of ring‐contracted (14‐crown‐5, 17‐crown‐6) and ring‐enlarged (16‐crown‐5, 17‐crown‐5, 19‐crown‐6, 20‐crown‐6) crown ethers and their complexes with alkali‐metal cations Na⁺ and K⁺ had been explored using density functional theory (DFT) at B3LYP/6‐31G* level in order to reveal the effects of the methylene‐chain length in a crown ether. The nucleophilicity of all crown ethers had been investigated by the Fukui functions. The quantum chemistry parameters, such as the energy gap (ΔE), the highest occupied molecular orbital energy (E_HOMO) and the lowest unoccupied molecular orbital energy (E_LUMO) for less‐symmetrical crown ethers and symmetrical frameworks (15‐crown‐5, 18‐crown‐6) had been calculated. In addition, the thermodynamic energies of complexation reactions had also been studied. The results of the DFT calculations show that the methylene‐chain length plays an important role in determining the structure characters of the crown ethers and also strongly influences the properties of the ethers. Some of the calculated results are in a good agreement with the experimental values.     

Solvation Effects on the Structure and Stability of Alkali Metal Carbenoids

s‐Block metal carbenoids are carbene synthons and applied in a myriad of organic transformations. They exhibit a strong structure–activity relationship, but this is only poorly understood due to the challenging high reactivity and sensitivity of these reagents. Here, we report on systematic VT and DOSY NMR studies, XRD analyses as well as DFT calculations on a sulfoximinoyl‐substituted model system to explain the pronounced solvent dependency of the carbenoid stability. While the sodium and potassium chloride carbenoids showed high stabilities independent of the solvent, the lithium carbenoid was stable at room temperature in THF but decomposed at ?10 °C in toluene. These divergent stabilities could be explained by the different structures formed in solution. In contrast to simple organolithium reagents, the monomeric THF‐solvate was found to be more stable than the dimer in toluene, since the latter more readily forms direct Li/Cl interactions which facilitate decomposition via α‐elimination.     

Effect of the EDL Structure on the Mechanism of Electroreduction of Adsorbed Intermediates

Effect of the ₁ potential on various kinetic modes of the -hydroxyethyl radical reduction is studied using laser photoemission (LPE). A charged proton donor is found to make no impact on the electron transfer rate during the reduction of adsorbed radicals. Experimental results fit the model proposed earlier for the electroreduction of intermediates, which includes two parallel pathways for electron transfer—onto an adsorbed radical and onto a metastable complex radical–proton donor. Demonstrated is a complete analogy between time-resolved voltammograms for LPE-generated intermediates and classic polarograms.     

Exclusive π Encapsulation of Light Alkali Metal Cations by a Neutral Molecule

Cation–π interactions are one of the most important classes of noncovalent bonding, and are seen throughout biology, chemistry, and materials science. However, in almost every documented case, these interactions play only a supporting role to much stronger covalent or dative bonds, thus making examples of exclusive cation–π bonding exceedingly rare. In this study, a neutral diboryne molecule is found to encapsulate the light alkali metal cations Li⁺ and Na⁺ in the absence of a net charge, covalent bonds, or lone‐pair donor groups. The resulting encapsulation complexes are, to our knowledge, the first structurally authenticated species in which a neutral molecule binds the light alkali metals exclusively through cation–π interactions.