Aggregation behavior of a model ionic liquid surfactant in monosaccharide + water solutions

Alkylimidazolium salts are a very important class of ionic liquids (ILs). The ILs containing long alkyl chains are a kind of model surfactants. In this paper, the aggregation behavior of 1-decyl-3-methylimidazolium chloride ([C(10)mim]Cl) was investigated for the first time in aqueous monosaccharide (glucose, galactose, xylose and arabinose) solutions by conductivity, fluorescence, NMR and dynamic light scattering (DLS). Thus a series of physico-chemical parameters for the aggregation of [C(10)mim]Cl-the critical aggregation concentration (CAC), ionization degree of the aggregates (α), the standard Gibbs energy of aggregation (ΔG(m)(0)), and the aggregation number (N) were derived from the experimental data. The results show that addition of small amounts of monosaccharides in aqueous solution can cause a variation in aggregation properties of the IL. The CAC values decrease with increasing molality of monosaccharides. In particular for different kinds of monosaccharides, we found that the CAC values are in the order: glucose>galactose (hexoses), xylose>arabinose (pentoses); xylose>glucose (1e2e3e4e), arabinose>galactoses (1e2e3e4a). These trends may be attributed to the slight difference in the stereo-structure of monosaccharide molecules. Finally a mechanism for the interaction of these monosaccharides with [C(10)mim]Cl was proposed.     

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.     

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.     

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.     

Applicability of the Bertrand, Acree, and Burchfield Method of Predicting the Relative Permittivity of Ternary Mixtures

The Bertrand, Acree, and Burchfield (BAB) method has been employed to predict the relative permittivity of the ternary system: N,N-dimethylformamide-2-methoxyethanol-1,2-dimethoxyethane at seven temperatures from –10 to +20°C using reported relative permittivities for the three constituents' binary systems: N,N-dimethylformamide-2-methoxyethanol, 2-methoxyethanol-1, 2-dimethoxyethane, N,N-dimethylformamide-l, 2-dimethoxyethane. The agreement between the predicted and the experimental values is 99 ± 1%.     

Molecular dynamics simulation of monoalkyl glycoside micelles in aqueous solution: influence of carbohydrate headgroup stereochemistry

Comparative molecular dynamics simulations of n-octyl-beta-D-galactopyranoside (beta-C8Gal) and n-octyl-beta-D-glucopyranoside (beta-C8Glc) micelles in aqueous solution have been performed to explore the influence of carbohydrate stereochemistry on glycolipid properties at the atomic level. In particular, we explore the hypothesis that differences in T(m) and T(c) for beta-C8Gal and beta-C8Glc in lyotropic systems arise from a more extensive hydrogen bonding network between beta-C8Gal headgroups relative to beta-C8Glc, due to the axial 4-OH group in beta-C8Gal. Good agreement of the 13 ns micelle-water simulations with available experimental information is found. The micelles exhibit a similar shape, size, and degree of exposed alkyl chain surface area. We find net inter- and intra-headgroup hydrogen bonding is also similar for beta-C8Gal and beta-C8Glc, although n-octyl-beta-D-galactopyranoside micelles do exhibit a slightly greater degree of inter- and intra-headgroup hydrogen bonding. However, the main distinction in the calculated microscopic behavior of beta-C8Glc and beta-C8Gal micelles lies in solvent interactions, where beta-d-glucosyl headgroups are considerably more solvated (mainly at the equatorial O4 oxygen). These results agree with preceding theoretical and experimental studies of monosaccharides in aqueous solution. A number of long water residence times are found for solvent surrounding both micelle types, the largest of which are associated with surface protrusions involving headgroup clusters. Our simulations, therefore, predict differences in hydrogen bonding for the two headgroup stereochemistries, including a small difference in inter-headgroup interactions, which may contribute to the higher T(m) and T(c) values of beta-C8Gal surfactants relative to beta-C8Glc in lyotropic systems.     

Kinetic study of the isotopic exchange of Na+ and Zn2+ ions on iron and chromium titanates

Iron(III) (FeTi) and chromium (III) titanates (CrTi) were prepared as cation exchange materials in a granular form. The rate of the isotopic exchange of Na⁺/*Na⁺ and Zn²⁺/*Zn²⁺ between aqueous solution and iron(III) and chromium(III) titanates in Na⁺ or Zn²⁺form has been carried out radiometrically in the 25-60 °C temperature range. The exchange rate is controlled by a particle diffusion mechanism and experimental and theoretical approaches have been used to obtain the rate of diffusion through the spherical particles of the exchangers. The values of self diffusion () of Na⁺ and Zn²⁺ ions were measured at different operation conditions, particle size, reaction temperatures and drying temperatures of the matrix. The values of kinetic and thermodynamic parameters were calculated and their significance discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

The 2-Methoxyethanol + 1,2-Dimethoxyethane + Water Ternary System. Static Relative Permittivities from −10 To +80°C

Static relative permittivities of the 2-methoxyethanol + 1,2-dimethoxyethane + water ternary solvent system were measured as a function of temperature (-10 = t/°C = 80) and of composition, over the whole molar fractions range 0 = x₂, x₂, x₃ = 1. The experimental values have been used to test some empirical relationships accounting for the dependence of e on T, x_i, and on T, x_i couples of values. A comparison between calculated and experimental data shows that these relationships can be profitably employed to predict e values in correspondence to experimental data gaps. The excess dielectric permittivity, e^E, assumes, in the most cases, negative values for any compositions of the mixtures, while the values of the excess molar polarization, P^E, are positive. The large values of the excess quantities are indicative of the strong specific interactions among similar, as well as different molecules in the mixtures. Discussion of the data in terms of Kirkwood correlation factor also gives information on the short-range intermolecular interactions among the components, suggesting the formation of two-components adducts rather than of than more complex moieties involving all three molecular species.     

Speeds of sound and isentropic compressibil- ities of cyclohexane+1,3-dioxolane+2-butanol and n-hexane+1,3-dioxolane+2-butanol

Speeds of sound of the ternary mixtures cyclohexane+1,3-dioxolane+2-butanol and n-hexane+1,3-dioxolane+2-butanol have been measured at the temperatures of 298.15 and 313.15 K. Isentropic compressibilities and excess isentropic compressibilities have been calculated from experimental data. We have also compared the experimental isentropic compressibilities with calculated values from the free length theory and the collision factor theory. Experimental results show positive values of excess isentropic compressibilities in almost the whole composition range for the ternary mixture containing cyclohexane, meanwhile they are negative for the mixture containing n-hexane. Such different behaviour of these systems is related to the large free volume shown by n-hexane. This revised version was published online in July 2006 with corrections to the Cover Date.     

Attachment of Chloride Anion to Sugars: Mechanistic Investigation and Discovery of a New Dopant for Efficient Sugar Ionization/Detection in Mass Spectrometers

A new method for efficient ionization of sugars in the negative‐ion mode of electrospray mass spectrometry is presented. Instead of using strongly hydrophobic dopants such as dichloromethane or chloroform, efficient ionization of sugars has been achieved by using aqueous HCl solution for the first time. This methodology makes it possible to use hydrophilic dopants, which are more appropriate for chromatographic separation techniques with efficient sugar ionization and detection in mass spectrometry. The interaction between chloride anions and monosaccharides (glucose and galactose) was studied by DFT in the gas phase and by implementing the polarizable continuum model (PCM) for calculations in solution at the high B3LYP/6‐31+G(d,p)//B3LYP/6‐311+G(2d,p) level of theory. In all optimized geometries of identified [M+Cl]^? anions, a non‐covalent interaction exists. Differences were revealed between monodentate and bidentate complex anions, with the latter having noticeably higher binding energies. The calculated affinity of glucose and galactose toward the chloride anion in the gas phase and their chloride anion binding energies in solution are in excellent agreement with glucose and galactose [M+Cl]^? experimental intensity profiles that are represented as a function of the chloride ion concentration. Density functional calculations of gas‐phase affinities toward chloride anion were also performed for the studied disaccharides sucrose and gentiobiose. All calculations are in excellent agreement with the experimental data. An example is introduced wherein HCl was used to effectively ionize sugars and form chlorinated adduct anions to detect sugars and glycosylated metabolites (anthocyanins) in real biological systems (Vitis vinifera grape extracts and wines), whereas they would not have been easily detectable under standard infusion electrospray mass spectrometry conditions as deprotonated species.     

Refractive Indices, Viscosities, and Densities for L-Cysteine Hydrochloride Monohydrate + D-Sorbitol + Water, and Glycerol + D-Sorbitol + Water in the Temperature Range between T=303.15 K and T=323.15 K

Viscosities, refractive indices, and densities for ternary systems of (L-cysteine hydrochloride monohydrate [LCHCMH] + D-sorbitol + water) and (glycerol + D-sorbitol + water) and binary systems of ([LCHCMH] + water) and (D-sorbitol + water) have been measured at several temperatures (between T=303.15 K and T=323.15 K) and mass fractions (0.1 to 0.8) at atmospheric pressure. For these mixtures, the experimental values of density were correlated with an experimental equation and the experimental values of viscosity were correlated with the Jones-Dole equation.     

Thermodynamics of amino acid dissociation in mixed solvents. 3: Glycine in aqueous glucose solutions from 5 to 45°C

The first thermodynamic dissociation constants of glycine in 5, 15 mass % glucose+water mixed solvents at five temperatures from 5 to 45°C have been determined from precise emf measrements of a cell without liquid junction using hydrogen and Ag-AgCl electrodes and a new method of polynomial approximation proposed on the basis of Pitzer's electrolytic solution theory in our previous paper. The results obtained from both methods agree within experimental error. The standard free energy of transfer for HCl from water to aqueous mixed solvent have been calculated and the results are discussed.     

Molecular Weight and Aggregation of Erwinia Gum in Aqueous Solutions

Erwinia(E) gum is composed of glucose, fucose, galactose and glucuronic acid. The weight-average molecular weights Mw, number-average molecular weights Mn and intrinsic viscosities[η] of the four fractions and the unfractionated E gum in aqueous solutions at desired temperatures were studied by light scattering, membrane osmometry, size exclusion chromatography(SEC) and viscometry. The experimental results prove that E gum formed aggregates in the aqueous solution at 25 ℃ and the aggregates were broken gradually with increasing temperature. The dissociation of the aggregates of E gum in the aqueous solution started at 36 ℃, and was completed at around 90 ℃. The [η] values of E gum and its fractions are much higher than those of the conventional polymers with the similar molecular weights, and decrease with increasing NaCl concentration.     

Measurements of densities,viscosities, speeds of sound and relative permittivities and excess molar volumes,excess isentropic compressibilities and deviations in relative permittivities and molar polarizations for dibutyl ether + benzene, + toluene and + p-xylene at different temperatures

The densities ρ, dynamic viscosities η, speeds of sound u, and relative permittivities ε_r, for (dibutyl ether + benzene, or toluene, or p-xylene) have been measured at different temperatures over the whole composition range and at atmospheric pressure. The mixture viscosities have been correlated with semi empirical equations. Calculations of the speed of sound based on Nomoto’s equation have been found to be close to experimental values for the three mixtures and at two temperatures. Excess functions such as excess molar volumes V_m^E, excess isentropic compressibilities κ_s^E, deviations in relative permittivities δε_r, and molar polarizations δP_m were calculated and fitted to Redlich–Kister type equations.     

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.     

Measurements of vapour-liquid equilibria,densities, viscosities and dielectric properties of cyclohexanone + triethylamine mixtures with respect to keto-enol tautomerism

Densities, ?, kinematic viscosities ν, refractive indices n_D referred to the sodium D-line, static relative permittivities ε, specific conductances κ and vapour-liquid equilibrium data for cyclohexanone + triethylamine mixtures have been determined at two temperatures. Excess properties of mixing calculated from these data indicate that in such mixtures considerable amounts of enol-amine associates are formed. The permittivity data indicate that the formation of associates is an exothermic process, which also has a marked influence on the thermodynamic excess properties of the mixtures. The enol-amine associates may undergo electrolytic dissociation. A common evaluation of static relative permittivities and specific conductances shows that for the mixture the conductance data are affected considerably by the formation of undissociated ion pairs in the sense of Bjerrum theory, especially at concentrations of the mixture where it is less polar. The conductance data are also influenced considerably by the fact that the ion pairs are solvated if the molar ratio of triethylamine exceeds 0.5.     

对二甲苯＋环己烷及对二甲苯＋二甲基亚砜的固液相平衡和过量吉布斯自由能

测定了对二甲苯＋环己烷及对二甲苯＋二甲基亚砜体系（均为简单低共熔混合物）的固液平衡相图，计算出它们在３１３．１５Ｋ的过量吉布斯自由能。结果表明两体系对理想溶液均产生正偏差。     

Distinguishing of linkage isomers of lactotetra oligosaccharides by using the relative ion intensity analysis of post-source decay fragment ions in curved-field reflectron matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The native oligosaccharides of lacto-N-neotetraose (Gal beta1-4GlcNAc beta1-3Gal beta1-4Glc; LNnT) and lacto-N-tetraose (Gal beta1-3GlcNAc beta1-3Gal beta1-4Glc; LNT) were analyzed by using curved-field reflectron matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Since a curved-field reflectron TOFMS enables a simultaneous focusing of a wide mass range of metastable fragment ions, the relative ion intensities in the post-source decay (PSD) mass spectra can be discussed. The PSD mass spectra of LNnT and LNT were distinguishable in their relative ion intensities. In the case of LNT, beta-elimination could occur in the N-acetyl glucosamine (GlcNAc) at the C-3 position, which was bonded by galactose (Gal); however, it did not occur in LNnT. The 3-O elimination caused a difference in the relative ion intensities in the PSD mass spectra of LNnT and LNT. The beta1-3 glycosyl linkage cleaved more easily than the beta1-4 glycosyl linkage in the MALDI-PSD fragmentation. An analysis of the relative ion intensities in the MALDI-PSD mass spectra of oligosaccharides was very useful for distinguishing the linkage isomers and for characterizing the types of glycosyl linkages.     

Study of intermolecular interactions through dielectric properties of the mixtures consisting of 1,4-butanediol,primary amyl alcohols and 1,4-dioxane at various temperatures

This paper presents relative permittivities, excess permittivities, effective dipole moments, and excess Kirkwood correlation factors of binary mixtures of 1,4-butanediol with two primary pentanol isomers [1-pentanol (amyl alcohol) + 3-methyl-1-butanol (isoamyl alcohol)] from T = (298.15 to 318.15) K at p = 101.3 kPa over the entire composition range. Experimental permittivity values for polar–non-polar binary systems of (1,4-dioxane + amyl alcohol or isoamyl alcohol) were also obtained as a function of composition at the same range of temperatures. The experimental permittivity data were fitted using Redlich–Kister equation to evaluate the adjustable parameters and the standard errors. From the experimental data, the excess parameters were calculated. In this work, variations of effective dipole moment and correlation factor were investigated using Kirkwood−Frohlich equation. The experimental data of measurements were used in the analysis of the homo- and hetero interactions occurring in these binary solutions.     

The effect of alternative carbohydrates on the growth and antibody production of a murine hybridoma

A murine hybridoma (CC9C10) was adapted to grow in media containing alternative carbohydrates to glucose. Cell yields relative to the glucose-based culture decreased in order of the following supplements: glucose = maltose > galactose > fructose = sorbitol = xylitol, although significant yields (> 50% of glucose control) were observed in all cultures. In the absence of glucose, glutamine consumption rates were enhanced significantly. Antibody production was directly related to the viable cell concentration in each culture and was independent of the phase of culture. A high specific antibody productivity (qMab) was observed in the cultures containing the polyols, sorbitol, or xylitol, even though the cell yields and growth rates were lower than the glucose-based control. The measured qMab in the xylitol culture was 5.6x that of the glucose culture and the volumetric yield of MAb was 29% higher.