Water-dimethyl Sulfoxide Mixtures Research Articles

Effect of ionic strength on the thermodynamic characteristics of complexation between Fe(III) ion and nicotinamide in water-ethanol and water-dimethyl sulfoxide mixtures

Solutions of iron(III) perchlorate in water, water-ethanol, and water-dimethyl sulfoxide solvents (\(x_{H_2 O} \) = 0.7 and 0.25 mole fractions) at ionic strength values I = 0.1, 0.25, and 0.5 are studied by IR spectroscopy. Analysis of the absorption bands of perchlorate ion shows that it does not participate in association processes. It is demonstrated that in the range of ionic strength values between 0 and 0.5 (NaClO4), it affects neither the results from potentiometric titration to determine the stability constants of the iron(III)-nicotinamide complex nor the thermal effects of complexation determined via direct calorimetry in a binary solvent containing 0.3 mole fractions (m.f.) of a non-aqueous component.

Micellization of dodecyltrimethylammonium bromide in water–dimethylsulfoxide mixtures: A multi-length scale approach in a model system

The micellization in mixed solvent was studied using conductimetry, density measurements (molar volumes), and small angle neutron scattering (SANS) to explore dodecyltrimethylammonium bromide (DTABr) micelle formation throughout the entire composition range of water–dimethylsulfoxide (DMSO) mixtures. As the concentration of DMSO was increased in the mixture, the critical micelle concentration (CMC) increased, the aggregation number decreased and the ionization degree increased, until no aggregates could be detected any more for DMSO molar fraction higher than 0.51. The results were consistent with the presence of globular micelles interacting via a coulombic potential. The experimental CMC values and aggregation numbers were successfully reconciled with a molecular thermodynamic model describing the micellization process in solvent mixtures (R. Nagarajan and C.-C. Wang, Langmuir 16 (2000) 5242). The structural and thermodynamic characterization of the micelles agreed with the prediction of a dissymmetric solvation of the surfactant entity: the hydrocarbon chain was surrounded only by DMSO while the polar head was surrounded only by water. The decrease in the ionization degree was due to the condensation of the counterions and was definitely linked to the geometrical characteristics of the aggregates and by no means to the CMC or salinity. This multi-technique study provides new insight into the role of solvation in micellization and the reason for the decrease in ionization degree, emphasizing the dissymmetric solvation of the chain by DMSO and the head by water. This is the first time that, for a given surfactant in solvent mixtures, micellization is described using combined analysis from molecular to macroscopic scale.

Pressure dependence on the single-particle dynamics and hydrogen-bond structural relaxation of water–DMSO mixtures under ambient and cold conditions

The effects of pressure on the single-particle translational and rotational dynamics and the hydrogen-bond structural relaxation of water–dimethyl sulfoxide (DMSO) mixtures were investigated under ambient and cold conditions using classical molecular dynamics simulations. We considered five different concentrations of DMSO with mole fractions X DMSO = 0.012, 0.09, 0.20, 0.35, and 0.50 and seven different pressures ranging from 0.1 to 500 MPa. It was found that the addition of DMSO to water leads to slow dynamics for both water and DMSO molecules under pressure. At very low concentrations of DMSO, water exhibits anomalous behavior with the application of pressure at 258 K, whereas DMSO molecules exhibit average pressure dependencies. The formation of strong hydrogen bonds between water and DMSO molecules occurs when DMSO is added to water, but the extended network is altered due to the absence of any hydrogen-bond donating ability of DMSO. Our calculated water–water and DMSO–water hydrogen-bond structural relaxation times show an initial decrease with the application of pressure at 258 K for solutions with low DMSO concentrations. However, at higher concentrations of DMSO, the relaxation times increase, on average, and no anomalous behavior of the dynamical properties is found on the application of pressure.

A Molecular Dynamics Study of DMPC Lipid Bilayers Interacting with Dimethylsulfoxide–Water Mixtures

The diffusion process of dimethylsulfoxide (DMSO) through zwitterionic dimyristoylphosphatidylcholine (DMPC) lipid bilayer was studied by means of molecular dynamics (MD) simulations. To account for the cryoprotectant concentration difference between the inside and the outside of the cell, dual DMPC lipid bilayers which separate two aqueous reservoirs with and without DMSO were modeled. The initial configuration of the simulation model had DMSO molecules present in one of the aqueous phases (outside the cell) at two different concentrations of ~3 and ~6mol%. MD simulations were performed on the systems for 50ns at 323K and 1bar. Although the simulation time considered in the study was insufficient for the DMSO molecules to reach the other aqueous phase and equilibrium, early stages of the diffusion process indicated that DMSO molecules had a tendency to diffuse towards the other aqueous phase. The effects of DMSO on bilayer structural characteristics during the diffusion process were investigated. Simulations were analyzed to correlate the following properties of lipid bilayers in the presence of two different aqueous phases: area per lipid, lipid thickness, mass density profiles, lipid tail order parameter and water dipole orientation. Area per lipid calculated for the leaflet facing the aqueous DMSO-water mixture did not show any significant difference compared to area per lipid for the DMSO-free pure DMPC bilayer. Mass density profiles revealed that DMSO molecules had a strong tendency to diffuse toward the aqueous phase with pure water. The lipid tail order parameter calculated for the sn-1 tail of the leaflet facing the aqueous DMSO-water mixture showed that the ordering of lipid tails decreased compared to the leaflet exposed to pure water. However, the ordering of lipid tails in a system where a single bilayer is hydrated by an aqueous DMSO-water mixture is far lower.

Thermochemical characteristics of nicotinamide protolytic equilibria in water-dimethylsulfoxide mixtures

The heat effects of nicotinamide protonation in water-dimethylsulfoxide (DMSO) solutions over the concentration range 0–0.75 DMSO mole fractions were determined calorimetrically at 25.00 ± 0.01°C and ionic strength 0.25 (NaClO4). Changes in the enthalpy of protonation as the content of DMSO increased were found to be described by an S-shaped curve. This curve shape was caused by the dynamics of reagent solvation contributions as the concentration of DMSO grew with the predominance of the nicotinamide solvation contribution.

Copolymerization of sodium 2-acrylamido-2-methylpropanesulfonate with sodium acrylate in water-dimethyl sulfoxide solutions

The solvent effect on the kinetic features of the synthesis and molecular characteristics of the copolymers in homogeneous radical copolymerization of sodium 2-acrylamido-2-methylpropanesulfonate with sodium acrylate in water and water-dimethyl sulfoxide mixtures (75: 25, 50: 50, 25: 75) at pH 9 and 60°C in the presence of potassium persulfate was studied

Spontaneous Cu(I)Br–PMDETA‐mediated polymerization of isobornyl methacrylate in heterogeneous aqueous medium at ambient temperature

AbstractIsobornyl methacrylate (IBMA), a bulky hydrophobic methacrylate, undergoes very fast polymerization, in bulk, with Cu(I)Br/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA)/ethyl‐2‐bromoisobutyrate system, at ambient temperature. IBMA also undergoes a spontaneous initiator‐free polymerization, at ambient temperature, with Cu(I)Br/PMDETA catalytic system in dimethyl sulfoxide–water mixtures. The rate of the polymerization is seen to increase with the water content up to 80 mol % of water. A possible intervention of air in initiation is proposed. The active Cu(0) formed by the disproportionation of Cu(I) species in aqueous medium probably plays a vital role for a possible air‐initiation of IBMA via single electron transfer‐living radical polymerization (SET‐LRP) mechanism. A high tolerance level to water under SET‐LRP conditions is demonstrated. The poly(IBMA) samples obtained exhibit low molecular weight distributions (1.1–1.3). Similar behavior was not observed with other common methacrylates such as methyl methacrylate, t‐butyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

The thermodynamic properties of solutions of L-ascorbic acid in dimethyl sulfoxide and water-dimethyl sulfoxide mixtures

Solutions of L-ascorbic acid (AA) in dimethyl sulfoxide (DMSO) and DMSO-water mixtures were studied by the densitometry, surface tension, and calorimetry methods. The apparent and partial molar volumes of AA in solutions at 298.15 K were calculated. Surface tension insignificantly increased as the concentration of AA in DMSO grew. The enthalpies of solution of AA in the solvents and the enthalpies of transfer of AA from water into DMSO and DMSO-water mixed solvents were calculated. The results obtained were explained by the existence of H-bonds between AA and DMSO molecules.

The thermochemical characteristics of solution of phenol and benzoic acid in water-dimethylsulfoxide and water-acetonitrile mixtures

The solution of phenol and benzoic acid in water-dimethylsulfoxide (DMSO) and water-acetonitrile (AN) mixtures was studied. As distinct from benzoic acid, the thermodynamic characteristics of solution of phenol sharply change at concentrations corresponding to a change in the character of cluster formation in water-DMSO and water-AN mixtures. Differences in the solvation of phenol and benzoic acid are explained by different mechanisms of the interaction of the solutes with clusters existing in binary mixtures.

Interactions of Nonprotic Organic Solvents with [Val5]angiotensin in Water

Intermolecular solvent-solute nuclear Overhauser effects have been used to explore interactions of the organic component of acetonitrile-water, acetone-water, and dimethyl sulfoxide-water mixtures with the peptide hormone [val(5)]angiotensin. As reported by the NOEs, many cross relaxation terms for interactions of these organic cosolvents are adequately accounted for using a hard spheres interaction model in which encounters of peptide and cosolvent molecules take place by mutual diffusion. However, there are indications of localized solvent-peptide interactions that are not well described by this model. In dimethyl sulfoxide-water at 0 °C, organic solvent near the C-terminal Phe8 residue and the Val3 residue produce strongly enhanced cross-relaxation terms. NOEs for all peptide N-H protons and the protons of the Tyr4 aromatic ring were significantly more positive than expected in 33% acetone-water (v/v) at 0 °C, while those for most side-chain protons were close to predictions of the hard sphere model. All peptide-organic solvent NOEs in 35% acetonitrile water (v/v) at 0 °C are consistent with the hard spheres interaction model.

Behavior of lignin in a dimethylsulfoxide—water mixture

The hydrodynamic behavior of lignin in a dimethylsulfoxide-water mixture have been studied at the temperature range of 20–60°C and at a water content from 0 to 30%. The rise of temperature was shown to deteriorate the quality of the solvent; i.e., the system under investigation belongs to systems with a lower critical solution temperature. The dimension of lignin particles in the mixed solvent decreases with an increasing proportion of water in the system.

The gibbs energies of transfer of glycine and glycinate ion from water into water-dimethyl sulfoxide mixtures

The Gibbs energies of transfer of glycine from water into water-dimethyl sulfoxide mixtures were determined at 298 K by measurements of substance distribution between immiscible phases. The enthalpy and entropy contributions to ΔG° of glycinate ion resolvation in water-dimethyl sulfoxide solvents were analyzed. The destabilization of glycinate ion was found to be largely determined by the energy component mainly. There was a correlation between the enthalpies of transfer of glycinate ion and the autoprotolysis constants of water-dimethyl sulfoxide solvents. The suggestion was made that changes in the Gibbs energies of glycinate ion resolvation in water-dimethyl sulfoxide and water-alcohol mixtures were largely determined by changes in the acid-base properties of the solvents.

A simple and efficient anionic chromogenic chemosensor based on 2,4-dinitrodiphenylamine in dimethyl sulfoxide and in dimethyl sulfoxide–water mixtures

Solutions of 2,4-dinitrodiphenylamine ( 1) in dimethylsulfoxide (DMSO) are colorless but upon deprotonation they become red. Addition of various anionic species (HSO 4 −, H 2PO 4 −, NO 3 −, CN −, CH 3COO −, F −, Cl −, Br −, and I −) to solutions of 1 revealed that only CN −, F −, CH 3COO −, and H 2PO 4 − led to the appearance of the red color in solution. The presence of increasing amounts of water in solutions containing 1 made it progressively selective toward CN − and the system with the addition of 4.3% (v/v) of water was highly selective for CN − among all anions studied. The experimental data collected indicated that proton transfer from 1 to the anion occurs, and a model was used to explain the experimental results, which considers two 1:anion stoichiometries, 1:1 and 1:2. For the latter, the data suggest that the anion forms firstly a hydrogen-bonded complex with a second anion equivalent necessary for the abstraction of the proton, with the formation of a [HA 2] − complex. The study performed here demonstrates the important role of the environment of the anion and 1 for the efficiency of the chromogenic chemosensor. Besides the different affinities of each anion for water, the solvation of both the anion and 1 is responsible for reducing the interaction between these species. In small amounts, water or hydrogen-bonded DMSO–water complexes are able to stabilize the conjugated base of 1 through hydrogen bonding, making 1 more acidic, which explains the change from 1:1 and 1:2 toward 1:1 1:anion stoichiometry upon addition of water. In addition, water is able to solvate the anion and also 1, which hinders the formation of 1:1 hydrogen-bonded 1:anion complexes prior to the abstraction of the proton.

The effect of carbonyl carbon atom replacement in acetone molecule (ACN) by sulfur atom (DMSO): Part II. Thermodynamic functions of complex formation of crown ethers with Na+ in mixed solvents

The thermodynamic functions of complex formation of benzo-15-crown-5 ether (B15C5) and sodium cation (Na+) in acetone–water mixtures at 298.15 K have been calculated. The equilibrium constants of B15C5/Na+ complex formation have been determined by conductivity measurements. The enthalpic effect of complex formation has been measured by the calorimetric method. The complexes are enthalpy-stabilized but entropy-destabilized in acetone–water mixtures. The effects of hydrophobic hydration, preferential solvation of B15C5 by a molecule of water and acetone, respectively and the solvation of Na+ on the complex formation processes have been discussed. The calculated thermodynamic functions of B15C5/Na+ complex formation and the effect of benzene ring on the complex formation have been compared with analogous data obtained in dimethylsulfoxide–water mixtures. The effect of carbonyl atom replacement in acetone molecule by sulphur atom (DMSO molecule) on the thermodynamic functions of complex formation has been analysed.

Dielectric properties of binary solvent mixtures of dimethyl sulfoxide with water.

In this paper, the dielectric properties of water-dimethylsulfoxide (DMSO) mixtures with different mole ratios have been investigated in the range of 1 GHz to 40 GHz at 298 K by using a molecular dynamics (MD) simulation. Only one dielectric loss peak was observed in the frequency range and the relaxation in these mixtures can be described by a single relaxation time of the Davidson-Cole. It was observed that within experimental error the dielectric relaxation can be described by the Debye-like model (β ≈ 1, S.M. Puranik, et al. J. Chem. Soc. Faraday Trans. 1992, 88, 433 – 435). In general, the results are very consistent with the experimental measurements.

Polarizable force field for water-dimethyl sulfoxide systems: II properties of mixtures by molecular dynamics simulations

A consistent polarizable force field for dimethyl sulfoxide (DMSO) with the TIP4P-FQ (fluctuating charge) water model was developed to explore the properties of pure DMSO liquid and the DMSO–water mixtures in this work. The DMSO–water mixtures at a range of concentrations of DMSO were selected to explore the unusual properties of them at 298 K and 1 atm. The radial distribution functions of neat DMSO liquid from the simulations with the current model are more excellently consistent with data from a neutron diffraction experiment than the additive models. More reasonable results for the static (radial distribution function, density, excess volume, heat of vaporization and mixing heat) and dynamic properties (lifetime of hydrogen bond, reorientational relaxation time and self-diffusion coefficient) of the mixtures over a range of composition were obtained by the current model and parameters than the previous additive models. The interaction between methyl hydrogen and water oxygen is mainly characteristic of weak hydrogen bond interactions and weaker than that between methyl hydrogen and DMSO oxygen. The hydrated methyl is more preferred than the methyl–methyl association. The enhanced structure of water and DMSO within the first shell is due to decrease of the water number in the hydrogen bond chain of DMSO– nwater–DMSO. The distributions and fluctuations of dipole moment can well reflect the polarization effect and the microscopic configures in the mixtures. The static dielectric permittivities of the DMSO–water mixtures are in well agreement with the corresponding experimental values.

The bulk properties of the water-dimethylsulfoxide system at 278–323.15 K and atmospheric pressure

The densities of water-dimethylsulfoxide (DMSO) mixtures were measured over the temperature range 278–323.15 K and over the whole range of compositions at atmospheric pressure. The partial molar volumes of water and dimethylsulfoxide, mixture volumetric thermal expansion coefficients, and partial molar volumetric thermal expansion coefficients of the components were calculated. The composition dependences of the density of the mixture passed a maximum at x ∼ 0.6 at all temperatures (x is the mole fraction of dimethylsulfoxide). The composition dependences of the partial molar volumes of water and DMSO also passed extrema.

Kinetic study of solvent effects on the hydrolysis of di-2-chloroaniline phosphate in dioxane and dimethyl sulfoxide-water medium

Kinetic study of di-2-chloroaniline phosphate was carried out in dioxane and dimethyl sulfoxide-water mixtures of varying compositions 20-50% (v/v). The rate of reaction increases with increasing proportion of dioxane and dimethyl sulfoxide at 80 and 90 °C. The activation parameters (E a , ΔH ≠ , ΔG * , -ΔS ≠ ) have been evaluated and variations of these parameters have been explained on the basis of solvent-solute interaction, solvent of the transition state of the medium.

The compressibility of water-dimethyl sulfoxide mixtures over the temperature and pressure ranges 278–323.15 K and 1–1000 bar

The compressibility coefficients of water-dimethyl sulfoxide (DMSO) binary liquid mixtures were measured over the temperature range 278–323.15 K at pressures from atmospheric to 1000 bar. At these state parameters, the partial molar volumes and partial molar compressibility coefficients \( \bar k_1 \) and \( \bar k_2 \) of water and DMSO were calculated. The dependences of the compressibility coefficients of mixtures on mixture composition passed a minimum. The minimum shifted to lower DMSO concentrations as the temperature increased. The dependences contained the inversion region where the k value was independent of pressure. The limiting molar partial compressibility coefficient of DMSO \( \bar k_2 \) was negative at 278.15 K and increased as the temperature grew.

Heat of dissolution of cellulose in water and water—dimethyl sulfoxide mixtures

The thermal effects of dissolution of cellulose in water and mixtures of water and dimethyl sulfoxide were determined. The point of view that the energetics of the reaction of cellobiose with aqueous-organic mixtures is a function of the intensity of the intermolecular interaction between the components and structure of the mixed solvent and the basicity of the organic component.