四苯硼钾由单-到不同混合溶剂的迁移自由能

KBPh4作为一种典型的大阴离子电解质 ,在研究与计算大分子电解质的迁移热力学性质中起着重要的作用 .讨论大分子电解质与不同溶剂间的作用 ,还可以为萃取、色谱及表面活性剂的研究提供理论依据 .一些文献及我们前文曾对四苯硼盐由水到一些纯溶剂 [1,2]及从水到某些水-有机混合溶剂中的标准迁移自由能进行了研究 [3],但对四苯硼盐在有机-有机混合溶剂中的研究报导极少 .本文对 KBPh4由水到水-异丙醇和由甲醇到甲醇-异丙醇混合溶剂的标准迁移自由能进行了研究和探讨 .1实验部分 1.1实验仪器及方法 　　用 CS501型超级恒温槽恒温 ;用 WF…     

V-shaped switching in ferroelectric liquid crystal mixtures induced by an achiral swallow-tailed material

A new ferroelectric liquid crystal, 1-ethylpropyl ( S )-2-[2-fluoro-4-(4'-decyloxybiphenylcarbonyloxy) benzoyloxy] propanoate, F , was synthesized and mixed with an achiral swallow-tailed material, 2-propylpentyl 4-(4'-nonyloxybiphenyl-4-carbonyloxy) benzoate, P , for the preparation of binary mixtures for the study. The binary mixtures gave a phase sequence SmA * -SmC * -SmX * . The electro-optic response of the mixtures in the ferroelectric SmC * phase was investigated. V-shaped switching was observed as the amount of the achiral swallow-tailed material became greater than 20 wt %. This result suggests that thresholdless, V-shaped switching in ferroelectric liquid crystal mixtures can be achieved by mixing a ferroelectric liquid crystal with an achiral swallow-tailed compound.     

用四氧化三锰加硫酸的方法制备不同含硫量的管理样

采用向Mn3O4中加入已知浓度的硫酸,制备不同硫含量的Mn3O4、MnO2、MnSO4的混合物管理样,将制备的混合物处理之后,用高频红外碳硫仪进行分析．结果表明,所得结果与实际含硫量基本相吻合．对硫管理样进行XRD分析,结果表明,硫管理样中的MnSO4含有结晶水,并由此得出碳硫仪测定结果与实际硫含量相符的原因．     

V-shaped switching in ferroelectric liquid crystal mixtures induced by an achiral swallow-tailed material

A new ferroelectric liquid crystal, 1-ethylpropyl (S)-2-[2-fluoro-4-(4′-decyloxybiphenylcarbonyloxy) benzoyloxy] propanoate, F, was synthesized and mixed with an achiral swallow-tailed material, 2-propylpentyl 4-(4′-nonyloxybiphenyl-4-carbonyloxy) benzoate,P, for the preparation of binary mixtures for the study. The binary mixtures gave a phase sequence SmA* -SmC* -SmX*. The electro-optic response of the mixtures in the ferroelectric SmC* phase was investigated. V-shaped switching was observed as the amount of the achiral swallow-tailed material became greater than 20 wt %. This result suggests that thresholdless, V-shaped switching in ferroelectric liquid crystal mixtures can be achieved by mixing a ferroelectric liquid crystal with an achiral swallow-tailed compound.     

Phase diagram and electro-optical Kerr effect of nematic mixtures containingtolane and biphenyl cores

An experimental phase diagram for two types of nematic liquid crystals and their binary mixtures was established by polarised optical microscopy and differential scanning calorimetry methods. The mixtures comprised a tolane-base liquid crystal, 4-heptyl-3-fluoro-4-isothiocyanatotolane (7TOLF), and a biphenyl-base nematogen, 4-heptyl-3-fluoro-4-isothiocyanatobiphenyl (7BF). The static Kerr effect and third-order non-linearity were investigated for 7TOLF and 7BF and their nematic mixtures within the isotropic phase. Both the compounds have a positive and large Kerr constant. The second-order phase-transition temperatures, T?, were determined for these mixtures. The linear dependence of (T - T?)^??1 on the Kerr constant is found to be in good agreement with the predications of the Landau–de Gennes model. The third-order non-linear susceptibility,χ⁽³⁾, values were determined for these mixtures.     

Merocyanine solvatochromic dyes in the study of synergistic effects in mixtures of chloroform with hydrogen-bond accepting solvents

The molar transition energy (E(T)) polarity values for the solvatochromic probes 2,6-diphenyl-4-(2,4,6-triphenylpyridinium)phenolate (1), 4[(1-methyl-4-(1H)-pyridinylidene)-ethylidene]-2,5-cyclohexadien-1-one (2), and 4-[4-(dimethylamino)styryl]-1-methylpyridinium iodide (3) were collected in binary mixtures comprising chloroform and a hydrogen-bond accepting (HBA) solvent [dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), acetone or acetonitrile], aiming to investigate the ability of the chlorinated component to act as hydrogen-bond donating (HBD) solvent. Plots of E(T) as a function of X(2), the mole fraction of chloroform, were obtained and the data were analysed to investigate the preferential solvation (PS) of each probe in terms of both solute-solvent and solvent-solvent interactions. For dyes 1 and 2 a strong synergistic behavior was observed for all mixtures studied, indicating that the dyes are preferentially solvated by complexes formed through hydrogen bonding between chloroform and the HBA component in the mixtures. A study of 1 in deuterated chloroform with an HBA component (DMF and DMA) demonstrated that while almost no differences occur with the DMF mixtures, the presence of deuterated chloroform in its mixtures with DMA increases the synergistic effect, suggesting that it interacts more strongly with DMA, making its mixtures more polar. These data were successfully fitted to a model based on solvent-exchange equilibria. The features of the mixtures with dye 3 revealed a very different profile in comparison with the other two dyes, which suggests that in mixtures containing chloroform, the microenvironment of the dye seems to be important in determining the contribution of the structure resonances responsible for the stability of the dye.     

Application of the Bahe's pseudolattice theory to water-1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) mixtures at 298.15K: Part II. Acidity scales

Molten salts at room temperature and their mixtures with water or molecular solvents are excellent candidates for future replacement of most of organic solvents used in many industrial processes. To make this possible and to allow efficient application, it is necessary to determine physico-chemical parameters (such as the acidity scales) for these reaction media. This work follows a study of the autoprotolysis constants (K(s)) of water-1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)) mixtures at 298.15K over the composition range of 0-77.43 vol.% bmimBF(4) [I. Bou Malham, P. Letellier, M. Turmine, Talanta 72 (2007) 155-164]. In this second analysis, we determined the values of the dissociation constant (pK(a)) of various conjugate acid-base pairs for the same water-bmimBF(4) mixtures, to establish acidity scales for each medium. These data can be used to produce proton buffer solutions and thus to control the acidity level of water-ionic liquid (IL) mixtures. We compare the values of pK(a) for acid-base pairs in water-bmimBF(4) mixtures with published values for water-methanol mixtures.     

Studies on quinoline derivatives and related compounds. II. Synthesis of 5-substituted 1-ethyl-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid

The cyclization of m-substituted anilinomethylenemalonates ( 1 ) in the presence of polyphosphate ester and some other cyclizing agents gave mixtures of the isomeric ethyl 5- ( 2 ) and 7-substituted 4-hydroxy-3-quinolinecarboxylates ( 3 ), which led to mixtures of the corresponding quinolinecarboxylic acids ( 4 and 5 ) by hydrolysis. The proportions of 4 and 5 in the mixtures were determined on the basis of their nmr spectra. Novel 5-chloro- ( 8a ), 5-methyl- ( 8b ) and 5-nitro-1-ethyl-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids were prepared and evaluated for antimicrobial activities. No significant activity, however, was noted.     

Dielectric Study of Homogeneity in Some Binary Liquids in Their Supercooled State

In this work, we report a dielectric study of some binary mixtures in their supercooled region over a frequency range of 10⁶ to 10^–3 Hz. Differential scanning calorimetry measurements have been made above 100K. The samples studied here are DL-lactic acid (88% in aqueous solution), binary mixtures of dimethyl sulfoxide and acetic acid, of propylene glycol and cyclohexanol, and of 4-methyl-3-heptanol and tritolyl phosphate. The frequency dispersion of the relaxation spectra and the temperature dependence of the relaxation process have been critically examined for heterogeneity. The mixtures of dimethyl sulfoxide and acetic acid reveal a 1:1 complex formation. Some evidence of heterogeneity was found only in mixtures of 4-methyl-3-heptanol and tritolyl phosphate. For comparison, we have also studied liquid mixtures of isopropylbenzene with small quantities of acetone or fluorobenzene. These mixtures showed no signs of heterogeneity, although the relaxation spectra are broader than the spectrum of pure isopropylbenzene.     

Thermodynamic and transport properties of argon/carbon and helium/carbon mixtures in fullerene synthesis

The equilibrium composition and thermodynamic and transport properties of argon; carbon and helium/carbon mixtures are calculated in the temperature range 300–20,000 K. The curves for the composition of mixtures of 50%, carbon in argon or helium are shown fir a pressure of 1.33 × 10⁴ Pa. The calculations for the heat capacity at constant pressure (C_p) and transport coefficients are validated with other studies, for the cases or pure argon and pure helium at a pressure of 10⁵ Pa. The properties of mixtures with various proportions of carbon in argon and helium are calculated. Results are presented at pressures of 105 and 1.33 × 10⁴ Pa, typical of reactors for the synthesis of fullerenes and nanotubes. It is observed that the properties of carbon and mixtures of carbon with a buffer gas (argon or helium) are very different from those of the buffer gas, thus the need to consider this effect in simulations. In general, the mixtures follow trends intermediate to those of the pure gases from which they are composed except for the thermal conductivity which shows a deviation from this tendency in the region between 11,500 and 19,000 K for argon/carbon mixtures and between 8,000 and 12,000 K for helium/carbon mixtures. Also, the electrical conductivity of mixtures of low carbon concentration is very close to that ofpure carbon. A datafile containing the transport properties of mixtures for pressures between 10⁴ and 10⁵ Pa is available free of charge from the authors.     

Reactive uptake of O3 by multicomponent and multiphase mixtures containing oleic acid

The heterogeneous reaction of O3 with lauric acid/oleic acid (LA/OA) mixtures and myristic acid/oleic acid (MA/OA) mixtures were studied as a function of composition, physical state, and microstructure at 298 K. Lauric acid and myristic acid are both alkanoic acids, whereas oleic acid is an alkenoic acid. Additionally, we investigated the uptake of O3 by multicomponent mixtures that closely represent the composition of meat-cooking aerosols. These measurements were performed with a rotating-wall flow-tube reactor coupled to a chemical ionization mass spectrometer. The reactive uptake coefficients (gamma) of O3 on liquid LA/OA and MA/OA solutions range from 4 x 10(-4) to 7.2 x 10(-4). The gamma values measured for solid-liquid LA/OA and MA/OA mixtures (which consist of solid LA or solid MA in equilibrium with a liquid) range from 2 x 10(-5) to 1.7 x 10(-4). These experiments show that only 7% solid by mass in the solid-liquid mixture can decrease gamma by an order of magnitude compared to the liquid mixtures. The gamma values for solid-liquid mixtures that closely represent the composition of meat-cooking aerosols range from 1.6 x 10(-5) to 6.9 x 10(-5). We found that gamma of solid-liquid mixtures depends on the microstructure of the mixtures, which in turn depends on the method of preparing the films. Furthermore, experiments employing solid-liquid mixtures show an increase in gamma with increasing film age. This can be explained either by the formation of a nonequilibrium phase followed by its relaxation to the stable phase or by Ostwald's ripening, which refers to a change in the solid microstructure due to a tendency to minimize the total surface free energy of the solid. We used the obtained gamma values to estimate OA lifetimes for polluted atmospheric conditions. For liquid solutions, the lifetimes were on the order of a few minutes. The lifetimes derived for solid-liquid mixtures are up to 75 min, significantly longer than for liquid solutions. Our study emphasizes the effect of the physical state and microstructure of multicomponent mixtures on the heterogeneous chemistry.     

Determination of reorganization energy of fluorenone and 4-hydroxyfluorenone in neat and binary solvent mixtures

Steady-state absorption and fluorescence measurements of fluorenone and 4-hydroxyfluorenone in neat and binary solvent mixtures were used to explore the reorganization energy in liquid system. The results of spectroscopic measurements were used to calculate, according to Marcus theory, the outer-sphere solvent reorganization energy, lambda(0), and the internal molecular reorganization energy, lambda(in). Preferential solvation of fluorenone and 4-hydroxyfluorenone in binary solvent mixtures has been studied by monitoring the outer-sphere solvent reorganization energy. In cyclohexane-tetrahydrofuran mixtures, the deviation from linearity in the lambda(0) versus the solution polarity is due to non-specific dipolar solvent-solute interactions. For cyclohexane-ethanol binary mixtures, both non-specific and specific (hydrogen bond) interactions contribute to the observed changes.     

咪唑类离子液体混合物吸收CO2性能研究

结合常规离子液体和功能型离子液体在吸收CO₂方面的优势,将两类咪唑类离子液体进行混合,对其吸收CO₂的效果和再生性能进行了实验研究。结果表明,两类咪唑类离子液体混合后流动性明显改善,与CO₂接触气液传质顺畅;常规离子液体[bmim][BF₄]和[bmim][Tf₂N]与胺功能型离子液体[NH₂e-mim][BF₄]混合物较单一的离子液体吸收CO₂的量大,[bmim][CH₃CO₂]与[NH₂e-mim][BF₄]混合后较单一的[bmim][CH₃CO₂]吸收量有明显的减低;随着常规咪唑类离子液体阳离子碳链增长,混合离子液体吸收CO₂的效果变强;与胺乙基功能型离子液体混合吸收CO₂时,阴离子为[Tf₂N]的常规咪唑类离子液体要比阴离子为[BF₄]的吸收效果好;离子液体混合物吸收CO₂后经再生循环利用10次,混合物质量基本不变,循环使用后吸收CO₂性能为初始吸收性能的75%~85%。     

Photocycloaddition Reactions of 2‐(Alk‐3‐en‐1‐ynyl)cyclohex‐2‐enones

The newly synthesized 2‐(alk‐3‐en‐1‐ynyl)cyclohex‐2‐enones 4 undergo photodimerization (chemo‐ and regio‐)selectively at the exocyclic C?C bond to give diastereoisomeric mixtures of 1,2‐dialkynyl‐1,2‐dimethylcyclobutanes. On irradiation of 4 in the presence of 2‐chloroacrylonitrile, cyclobutane formation occurs again (chemo‐ and regio‐)selectively at the exocyclic C?C bond to afford diastereoisomeric mixtures of 2‐alkynyl‐1‐chloro‐2‐methylcyclobutanecarbonitriles. Similarly, compounds 4 undergo photoaddition to 2,3‐dimethylbuta‐1,3‐diene exclusively at the exocyclic C?C bond to afford mixtures of [2+2] and [4+2] cycloadducts.     

Thermal analysis and X-ray studies of chiral ferroelectric liquid crystalline materials and their binary mixtures

Summary Thermal properties of a homologous series of ferroelectric liquid crystals S-(-)-[4-(2-n-alkoxy-propionyloxy)]biphenyl-4'-[n-alkoxy-(3,5-dimethyl)]benzoate have been investigated by polarizing optical microscopy and differential scanning calorimetry. The mesophases were identified and confirmed by X-ray too. Three binary mixtures were prepared from the individual homologues. In one of the mixtures (Mix1), the ferroelectric SmC* phase has broadened and became enantiotropic. This mesophase remained monotropic in the other two mixtures (Mix2, Mix3). The chiral nematic N* phase did not appear in Mix1, but remained monotropic for the other two mixtures. Two molecular parameters, the layer spacing and the average intermolecular distance have been calculated from the X-ray results for the homologues and their mixtures. An intercalated tail-to-tail packing of molecules was found both in the single compounds and their mixtures resulting in the layer spacing about half of the molecular length of the single compounds.     

Mesophase behaviour of binary mixtures of bent-core and calamitic compounds

The mesophase behaviour of binary mixtures of bent-core and calamitic liquid crystals is presented. The nematogenic 4,6-dichloro-1,3-phenylene bis[4′-(10-undecen-1-yloxy)-1,1′-biphenyl-4-carboxylate] (I) was the banana-shaped component. As the calamitic compound ethyl 4′-(9-decen-1-yloxy)-1,1′-biphenyl-4-carboxylate (II), similar to one arm of the bent-core molecule, was used which exhibits smectic phases in a wide temperature range. A total of six mixtures with different compositions were prepared and studied by polarising optical microscopy, differential scanning calorimetry and X-ray diffraction on non-oriented samples. In the mixtures, a nematic phase is not concomitant with smectic A phase, and the temperature range of both phases highly depends on the concentration of the comprising compounds. Lowered melting temperatures have been observed for all mixtures with respect to that of the pure compounds. Unforeseen finding is the induction of a monotropic SmC phase in mixtures with lowest concentration of the bent-core compound. Semi-empirical quantum-chemical calculations have also been performed. Based on the calculated molecular conformation, as well as on collected X-ray diffraction data, a model for a possible self-assembly of the banana-shaped and calamitic compounds is proposed.     

Phase diagrams and physical properties of binary ferroelectric mixtures based on a series of chiral α-cyanocinnamate derivatives

We report a detailed investigation of binary mixtures composed of members of the homologous series of (S)-4′-(2-n-alkoxypropanoyloxy)biphenyl-4-yl 4-n-alkoxy- f-cyanocinnamates. The phase transition curves for these mixtures have no minima. On the contrary, eutectic behaviour was obtained if the members of this homologous series were mixed with structurally different chiral cinnamic acid derivatives and other ferroelectric liquid crystal materials. Spontaneous polarization, tilt angle and dielectric constant results were obtained for three of the single compounds and nine ferroelectric mixtures.     

Stability of mixtures of charged silica, silica-alumina, and magnetite colloids

We report experiments on the stability of aqueous mixtures of charged colloidal magnetite and charged silica and silica covered with alumina particles of similar size. First, positively charged magnetite dispersions were mixed with negatively charged silica dispersions at pH 4, at different volume ratios and low colloid volume fractions, producing mixtures which were stable over a period of weeks despite the expected electrostatic attraction between the oppositely charged particles. When magnetite particles were mixed with positively charged silica covered with alumina at pH 4 under exactly the same conditions, some of the systems separated to form a magnetite sediment. When the volume fraction of the initial dispersions was increased, the behavior of the mixtures was the opposite: positive magnetite/negative silica mixtures were unstable at intermediate volume ratios. The unexpected behavior of the mixtures was investigated by means of electrophoretic mobility, initial susceptibility, and dynamic light scattering measurements as well as sedimentation experiments.     

Ultrafast molecular dynamics of liquid aromatic molecules and the mixtures with CCl4

The ultrafast molecular dynamics of liquid aromatic molecules, benzene, toluene, ethylbenzene, cumene, and 1,3-diphenylpropane, and the mixtures with CCl(4) have been investigated by means of femtosecond optical heterodyne-detected Raman-induced Kerr effect spectroscopy. The picosecond Kerr transients of benzene, toluene, ethylbenzene, and cumene and the mixtures with CCl(4) show a biexponential feature. 1,3-Diphenylpropane and the mixtures with CCl(4) show triexponential picosecond Kerr transients. The slow relaxation time constants of the aromatic molecules and the mixtures with CCl(4) are qualitatively described by the Stoke-Einstein-Debye hydrodynamic model. The ultrafast dynamics have been discussed based on the Kerr spectra in the frequency range of 0-800 cm(-1) obtained by the Fourier transform analysis of the Kerr transients. The line shapes of the low-frequency intermolecular spectra located at 0-180 cm(-1) frequency range have been analyzed by two Brownian oscillators ( approximately 11 cm(-1) and approximately 45 cm(-1) peaks) and an antisymmetric Gaussian function ( approximately 65 cm(-1) peak). The spectrum shape of 1,3-diphenylpropane is quite different from the spectrum shapes of the other aromatic molecules for the low magnitude of the low-frequency mode of 1,3-diphenylpropane and/or an intramolecular vibration. Although the concentration dependences of the low- and intermediate-frequency intermolecular modes (Brownian oscillators) do not show a significant trend, the width of high-frequency intermolecular mode (antisymmetric Gaussian) becomes narrower with the higher CCl(4) concentration for all the aromatics mixtures with CCl(4). The result indicates that the inhomogeneity of the intermolecular vibrational mode in aromatics/CCl(4) mixtures is decreasing with the lower concentration of aromatics. The intramolecular vibrational modes of the aromatic molecules observed in the Kerr spectra are also shown with the calculation results based on the density functional theory.     

Variation of Hypersound Velocity in the Isotropic Phase of Liquid Crystal Mixtures

The hypersound velocity in a series of binary mixtures containing the constituents 4-n-pentyl-4'-cyanobiphenyl and 4-cyano-4'(2-methyl)butoxybiphenyl has been measured using Brillouin scattering techniques. Measurements have been made in the isotropic phase of the mixtures over the temperature range 30°C to 80°C. A simple theory for the observed velocity variations is proposed and compared with the experimental data. Agreement is found to be excellent over the temperature range studied.