Studies on Associated Solutions. Part II. Physicochemical Properties of Acetonitrile-Propan-2-ol Mixtures

Abstract

The ¹H-NMR spectra of liquid binary mixtures of acetonitrile and propan-2-ol, were recorded at 298 K over almost the whole range of the mixed solvent compositions. From these data were found the values of the spectral parameter, Δδ(ACN-PrOH-2). The densities (d ₁₂) and relative permittivities (?₁₂) of the mixed solvent were measured at 288.15K, 293.15K, 298.15K, 303.15K and 308.15K, as well as refractive indices at 298.15K. From all these data, the molar volumes (V _m), temperature coefficients of relative permittivities (α_n) and their deviations from ideality were calculated. Additionally, the Kirkwood's correlation factors (g _K) were found. The values of these properties are discussed in terms of interactions of acetonitrile with propan-2-ol.     

2-Metoxyethanol-Acetonitrile Binary Mixtures and Their Physicochemical Properties

Abstract

Densities (d ₁₂) and relative permittivities (\Varepsilon₁₂) have been measured for 2-metoxyethanol (ME) and acetonitrile (ACN) binary liquid mixtures over their whole compositions ranges at various temperatures ranging from 288.15K to 308.15K. The experimental data were used to test some empirical equations of the type: y ₁₂=y ₁₂(t) and y ₁₂=y ₁₂(X ₁) (where: y ₁₂-d ₁₂ or \Varepsilon₁₂). From all these data, the excess molar volumes (V ^E _m), temperature coefficients of relative permittivities (α₁₂) and the excess extrathernmodynamic parameters \Varepsilon^E were calculated. The ¹H-NMR spectra of liquid binary mixtures of ME and ACN, were recorded at 298 K over almost the whole range of the mixed solvent compositions. From these data the values of the values of the spectral structural parameters were found, Δδ(ME-ACN). The values of these structural parameters are discussed in terms of interactions of 2-metoxyethanol with acetonitrile.     

Physicochemical Methods Used to Study Internal Structures of Liquid Binary Mixtures

Abstract

Different methods, based on application of studies of intensive physicochemical properties of liquid binary mixtures and ¹H-NMR spectral measurements, used in the analysis of intermolecular interactions and estimation of the internal structure of these mixtures and here reviewed.     

The Structures and Physicochemical Properties of Mixtures of Water-Soluble Polymers

Because data on structure, component interaction, physical properties, and compatibility of polymer blends containing native polysaccharides is very sparse, we have used optical and electron microscopy, X-ray diffraction, IR spectroscopy, sorption capacity methods, and estimation of thermodynamic data to investigate the structural, physicochemical, and physicomechanical properties of mixtures of carboxymethylcellulose with poly(vinyl alcohol) and of mixtures of chitosan with poly(vinyl alcohol), to discover relationships between the structures of the systems and their physicochemical characteristics and other properties, to determine the compatibility of components, and to discover methods and conditions for their synthesis. It was found that for some component ratios in these systems there is some interaction and some compatibility, with the result that the structures of the blends are less heterogeneous than those of the individual components. One effect of this is that the physicomechanical properties of the blends can be superior to those of the individual components, particularly for carboxymethylcellulose–poly(vinyl alcohol) mixtures.Presented at: International Symposium on Separation and Characterization of Natural and Synthetic Macromolecules, Amsterdam, The Netherlands, February 5–7, 2003     

Acetonitrile - 2-Methyl-Propan-1-ol and Acetonitrile - 2-Methyl-Propan-2-ol Binary Mixtures and their Physicochemical Properties

The 1 H-NMR spectra of liquid binary mixtures of acetonitrile with 2-methyl-propan-1-ol (i-BtOH) and 2-methyl-propan-2-ol (t-BtOH), were recorded at 298 K over almost the whole range of mixed solvent compositions. From these data the values of spectral parameters, j i (ACN-i-BtOH) and j i (ACN-t-BtOH) were found. The relative permittivities ( k 12 ) and the densities ( d 12 ) of the mixed solvents were measured at 288.15 K, 293.15 K, 298.15 K, 303.15 K and 308.15 K. The experimental data were used to test some empirical equations of the type: y 12 = y 12 ( t ) and y 12 = y 12 ( X 1 ) [where: y 12 = d 12 or k 12 ]. From all these data, the deviations from ideality molar volumes , temperature coefficients of relative permittivities ( f 12 ) and the excess extrathermodynamic parameters were calculated. The values of these structural parameters are discussed in terms of interactions of acetonitrile with both alcohols.     

Physicochemical Properties of High-Entropy Oxides

The development of industry has triggered an increasingly severe demand for new functional materials. In recent years, researches on high-entropy oxides (HEOs) are more comprehensive and in-depth, and their fascinating properties are gradually known to the public. The unique elemental synergistic effect and lattice distortion endow the high-entropy family with various untapped potential, and wide application fields and outstanding performance of HEOs make them candidates for future materials. In this review, the concept, structure, and synthesis of HEOs are firstly highlighted. Secondly, a variety of excellent properties and applications in the fields of mechanics, electrics, thermotics, optics and magnetics are summarized. This work provides a comprehensive overview about HEOs, facilitating the development of modern functionalities of the high-entropy family.     

球磨处理对豌豆淀粉结构及理化性质的影响

为探究球磨研磨处理对豌豆淀粉结构及性质的影响,采用扫描电镜、激光粒度分析仪、X-射线衍射仪、傅立叶红外光谱仪、差示扫描量热仪、快速黏度分析仪等分析手段研究经研磨处理后豌豆淀粉颗粒形貌、晶体结构和理化性质。结果表明,淀粉颗粒形貌由光滑的多角形变为表面粗糙的不规则形状,处理后豌豆淀粉粒度增大,粒度中位径达到23.28μm,偏光十字消失;淀粉颗粒结晶结构被破坏,由多晶态向无定形态转变,呈现非晶化状态;研磨过程淀粉无新的基团产生,淀粉颗粒由有序结构向无序化结构转变;热焓值、糊化温度均显著降低,热糊稳定性好,处理后豌豆淀粉具有较好的热糊稳定性和冷糊力学稳定性。     

酸解淀粉物理化学性质的研究

玉米淀粉和马铃薯淀粉分别在35C条件下用浓度为2．4mol／L的HCI处理不同时间,采用X射线衍射分析、差热分析和扫描电镜等测试方法对酸解后的淀粉颗粒进行结构和性能分析。结果表明,淀粉的酸解过程可分为两个阶段：首先淀粉无定形区进行水解,颗粒结晶度、结晶热稳定性和酶解速率增加;随着酸解时间的延长,结晶结构受到破坏,热稳定性降低,达到酶解平衡的时间减少。酸解4d时,玉米淀粉和马铃薯淀粉颗粒的结晶均最完整,结晶转变温度最高,分别为87．0C和93．5C。     

气流超微粉碎对蜡质玉米淀粉结构及理化性质的影响

为探究气流超微粉碎对蜡质玉米淀粉结构及性质的影响,采用扫描电镜、激光粒度分析仪、X-射线衍射仪、红外光谱仪、差示扫描量热仪、快速黏度分析仪等分析手段研究经微细化处理后蜡质玉米淀粉颗粒形貌、晶体结构和理化性质。结果表明,淀粉粒径明显变小,微细化蜡质玉米淀粉粒度中位径减小到6.43μm,粉碎后淀粉颗粒仍为A型结构,颗粒结晶结构被破坏,由多晶态向无定形态转变,粉碎过程淀粉无新的基团产生;热焓值、糊化温度均降低,热糊稳定性好;持水能力增加,冻融稳定性好,微细化蜡质玉米淀粉具有较好的热糊稳定性和冷糊力学稳定性。     

定位对应指数与多氯联苯醚理化性质的构效关系

通过计算多氯联苯醚(PCDEs)所有209种可能分子结构的原子特征值,利用分子图形技术获得了定位对应指数;以106种PCDEs的理化性质实验值为建模样本,由多元回归方法建立了PCDEs的饱和蒸气压(P0L)、水溶解度(SW)和正辛醇,水分配系数(KOW)的定量结构一性质相关模型,相关性良好(r＞0.98),估算的平均误差分别为0.12、0.28和0.09.利用此方程对另外103个未见实验数据报道的多氯联苯醚分子的理化性质进行预测,结果和相同氯原子数的实验平均值较为接近,预测能力优于文献.     

H-NMR Spectral and Dielectric Behaviours of the 2-Metoxyethanol-Tetrahydrofuran Solvent System

Abstract

Relative permittivities (E ₁₂) have been measured for 2-metoxyethanol (ME)-tetrahydrofuran (THF) binary liquid mixtures over the whole compositions range at various temperatures ranging from 291.15 K to 308.15 K. The experimental data were used to test some empirical equations of the type: y ₁₂ = y ₁₂(t) and y ₁₂ = y ₁₂ (X ₁) [where: y ₁₂-E ₁₂]. From all these data, the temperature coefficients of relative permittivities (α₁₂) and the excess extrathermodynamic parameters ε^E were calculated. The ¹H-NMR spectra of liquid binary mixtures of ME and THF, were recorded at 298 K over almost the whole range of the mixed solvent compositions. From these data the values of the values of the spectral structural parameters were found, δδ(ME-THF). These structural parameters as a function concentration suggest the formation of stable 3ME.THF types intermolecular complexes.     

四丁基季鏻羧酸盐离子液体的物理化学性质与CO2溶解度

在298.15-348.15 K温度范围内,测定了四种四丁基季鏻羧酸盐离子液体([P₄₄₄₄][CA])的密度、粘度、折射率、电导率等物理化学性质,得出了其随温度的变化关系,并获得了不同温度下该类离子液体的热膨胀系数。其次,在1个大气压和313.15 K温度下,测定了CO₂在该类离子液体中的溶解度,结果表明,四丁基季鏻丁酸盐吸收CO₂的性能最好,吸收量为0.4 mol·mol^-1,平衡时间小于5 min。     

To the Understanding of the Structural Sensitivity of the Temperature Coefficient of Internal Pressure

The previously found empirical relationships between the temperature coefficient of internal pressure, on the one hand, and the structure and its evolution in liquids due to variations of temperature and concentration, on the other, are interpreted in terms of the peculiarities of intermolecular interactions. Analysis has revealed that the curves of the temperature dependences of internal pressure P _i(T) of associated liquids are directed upward by their concavity; they have a minimum and asymptotically tend toward P _i = 0 at T→∞. The curves P _i(T) of weakly associated liquids are directed downward by their concavity and have no extrema, but asymptotically tend to zero at T→∞.Original Russian Text Copyright © 2004 by V. N. Kartsev__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 877–882, September–October, 2004.     

X-Ray Studies of 2-Methyl-2-Propanol Solution in Cyclohexane

Abstract

Changes in the mean least intermolecular distances in a solution of 2-methyl-2-propanol in cyclohexane with increasing concentration of the former were found to be non-linear. Both in the range of low (0.005–0.04 molar fraction) and high (0.45–0.75 molar fraction) concentrations of the solutions studied local maxima of the mean least intermolecular distance were observed. In the range from 0.8 to 1 molar fraction the value of this parameter remained constant. Results obtained in this work prove the absence of the specific structural properties of a low concentration alcohol solution observed in other solvents. The occurrence of the local maxima proves that cyclohexane is a non-active solvent. Owing to this the molecules of the solute and the solvent assume positions ensuring homogeneity of the solvents.     

Crystallographic and Inclusion Properties of some Diacetylated Calix[4]arenes

Three 5,17-diacetylcalix[4]arene derivatives 3–5 have been prepared, evaluated for inclusion properties, and their single crystal X-ray structures determined. The diacetyl calixarenes 3 and 4 were obtained by acetylation of their parent dimethoxy 1 or dipropoxy 2 compounds, respectively, whereas 5,17-diacetyl-25,26,27,28-tetrapropoxycalix[4]arene 5 was prepared by alkylation of 4. Crystallisation of 3 resulted in no inclusion from chloroform, but yielded lattice inclusion compounds from acetonitrile or acetone. The calixarene 3 maintains its cone conformation in these crystals, but displays degrees of distortion depending upon the included solvent. Crystal structures of solvent-free 4 and 5 are also described. A new preparation of the monomethoxy derivative 6 is described, and its X-ray structure with chloroform guest is analysed.     

Experimental and Theoretical Insights into the Optical Properties and Intermolecular Interactions in Push-Pull Bromide Salts

Experimental and theoretical insights into the nature of intermolecular interactions and their effect on optical properties of 1-allyl-4-(1-cyano-2-(4-dialkylaminophenyl)vinyl)pyridin-1-ium bromide salts ( I and II ) are reported. A comparison of optical properties in solution and in the solid-state of the salts ( I and II ) with their precursors ( Ia and IIa ) is made. The experimental absorption maxima (λ_max) in CHCl₃ is at 528 nm for I and at 542 nm for II , and a strong bathochromic shift of ∼110 nm is observed for salts I and II compared with their precursors. The absorption bands in solid-state at ∼627 nm for I and at ∼615 nm for II that are assigned to charge transfer (CT) effect. The optical properties and single crystal structural features of I and II are explored by experimental and computational tools. The calculated λ_max and the CT are in good agreement with the experimental results. The intermolecular interactions existing in the crystal structures and their energies are quantified for various dimers by PIXEL, QTAIM and DFT approaches. Three types of interactions, (i) the cation⋅⋅⋅cation interactions, (ii) cation⋅⋅⋅anion interactions and (iii) anion⋅⋅⋅anion interactions are observed. The cationic moiety is mainly destabilized by C−H⋅⋅⋅N/π and π⋅⋅⋅π interactions whereas the cation and anion moiety is predominantly stabilized by strong C−H⋅⋅⋅Br⁻ interactions in both structures. The existence of charge transfer between cation and anion moieties in these structures is established through NBO analysis.     

Physicochemical properties of SARS-CoV-2 for drug targeting,virus inactivation and attenuation,vaccine formulation and quality control

The material properties of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its proteins are discussed. We review the viral structure, size, rigidity, lipophilicity, isoelectric point, buoyant density and centrifugation conditions, stability against pH, temperature, UV light, gamma radiation, and susceptibility to various chemical agents including solvents and detergents. Possible inactivation, downstream, and formulation conditions are given including suitable buffers and some first ideas for quality-control methods. This information supports vaccine development and discussion with competent authorities during vaccine approval and is certainly related to drug-targeting strategies and hygienics. Several instructive tables are given, including the pI and grand average of hydropathicity (GRAVY) of SARS-CoV-1 and -2 proteins in comparison. SARS-CoV-1 and SARS-CoV-2 are similar in many regards, so information can often be derived. Both are unusually stable, but sensitive at their lipophilic membranes. However, since seemingly small differences can have strong effects, for example, on immunologically relevant epitope settings, unevaluated knowledge transfer from SARS-CoV-1 to SARS-CoV-2 cannot be advised. Published knowledge regarding downstream processes, formulations and quality assuring methods is, as yet, limited. However, standard approaches employed for other viruses and vaccines seem to be feasible including virus inactivation, centrifugation conditions, and the use of adjuvants.     

Densities and relative permittivities for mixtures of 2-methoxyethanol with DEA and TEA, at various temperatures

Densities () and relative permittivities () of numerous binary mixtures of 2-methoxyethanol (ME) (1)+diethylamine (DEA) (2) at four temperatures and 2-methoxyethanol (1)+triethylamine (TEA) (2) at five temperatures, between (291.15 and 313.15) K, are reported. These results are used to calculate excess molar volumes, and deviations in the relative permittivities. The results are fitted to the Redlich-Kister polynomial equation to estimate the binary coefficients and standard errors. Furthermore, the experimental results are used to disclose the nature of binary interactions in the bulk of studied the binary mixtures.This revised version was published online in November 2005 with corrections to the Cover Date.     

The length of the polymethine chain and the spectral-luminescent properties of symmetrical cyanine dyes

The general characteristics that relate the length of the polymethine chain of symmetrical cyanine dyes to their spectral-luminescent properties depending on the electron-donor character of the heterocycles and the nature of the solvent are formulated. For various types of symmetrical cyanines, the Stokes shifts decrease with the elongation of the polymethine chain due to weakening of the vibronic interactions. The vinylene shifts of the band maxima are essentially constant and fall within the range 100 to 130 nm depending on the nature of the heterocycles and the solvent. When the polymethine chain elongates the fluorescence quantum yields first increase and then decrease. The greater the effective length of the heterocycle the stronger the decrease. The fluorescence decay occurring when the polymethine chain gets longer is associated with intensification of the internal conversion. For symmetrical cyanines, the changes in the shapes of the electronic bands (their width, asymmetry, excess, and fine structure) as the chain elongates are governed by the competing effects of the vibronic and intermolecular interactions. The former decrease as the chain lengthens, causing the narrowing of the absorption bands for the lower vinylogs. On the other hand, the latter increase as chain lengthens, which leads to broadening of the bands for the higher vinylogs. The higher the solvent nucleophilicity and the greater the deviation of the electron-donor ability of the heterocycle from the average value the greater the broadening. Any elongation of the polymethine chain of symmetrical cyanines causes only narrowing of the bands and an increase in the asymmetry, excess, and structuring in the fluorescence spectra, which, unlike the absorption spectra, is independent of the electron-donor character of the heterocycles and the nature of the solvent. These effects are caused by the fact that, in contrast to absorption, changes in the shape of emission bands with increasing chain length are governed predominantly by vibronic rather than by intermolecular interactions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1227–1239, July, 1994.     

Structral and thermodynamic characteristics and intermolecular interactions in aqueous solutions of diols

The structural and thermodynamic characteristics of aqueous solutions of ethanediol, 1,2-and 1,3-propanediols, and 1,2-and 1,4-butanediols were calculated over the whole range of the compositions of the mixtures. The specific and nonspecific components of the total energy of intermolecular interactions were determined. The boundaries of the concentration regions with different structural organizations of solutions were established, and the parameters of preferable solvation of the solution components were evaluated.