Aqueous Solutions Of Dimethyl Sulphoxide Research Articles

Determination of Solute-Solute and Solute-Solvent Interaction of Pyrimidine-5-Carbonitrile in Aqueous DMSO at 298.15 K

Introduction: In this reported work, we have used 80 % aqueous dimethyl sulphoxide (DMSO) for density and viscosity measurement of pyrimidine-5-carbonitrile at 298.15 K. The obtained experimental results show that as concentration increases density and viscosity increases. From the results of density and viscosity, we have found apparent molar volume, limiting apparent molar volume, semi-empirical parameters, Falkenhagen coefficients and Jones Dole coefficients. Method: The apparent molar volume and limiting apparent molar volume having negative values indicated electostrictive solvation of ions and weak or absence of ion solvent interactions respectively. Result & Discussion : Falkenhagen coefficients are independent of concentration and possess positive values that shows strong solute-solute interactions. Jones-Dole coefficient with negative value shows weak solute-solvent interactions. The strong solute-solute interactions were present in A-1 as compared to A-2 compound because of the high electronegativity of oxygen atom. These parameters provides information about the type of the molecular interactions such as solute-solute, solute-solvent and solvent-solvent. Conclusion: We have reported density and viscosity study of 4-amino-2-hydroxy-6- phenylpyrimidine-5-carbonitrile and 4-amino-2-mercapto-6-phenylpyrimidine-5-carbonitrile in 80 % aqueous DMSO solution at 298.15 K. A stronger molecular association is observed in A-2 than A-1 shown by negative values of Øv.

A selective chemosensor for fluoride ion and its interaction with Calf Thymus DNA

The amido-Schiff base 1 (N1, N3-bis (2-nitrobenzylidene)benzene-1,3-dicabohydrazide) containing a CONH group and CHN linkage has been synthesized by the condensation between isophthalic acid dihydrazide and o-nitrobenzaldehyde. This molecule can act as a fluoride ion sensor with high selectivity and sensitivity. Presence of nitro group in the phenyl ring may be responsible for the detection of fluoride ion visually with a dramatic color change from colorless to deep red in aqueous dimethyl sulphoxide solution. This Schiff base can be used as test kit for sensing of fluoride ion in the solid state. Compound 1 can detect fluoride also in commercially available toothpaste. As the compound has adequate solubility in DMSO–water mixture (7:93, v/v) and having some hydrogen bond donor and acceptor centers, we have investigated its nature of binding with Calf Thymus-DNA (CT-DNA) using theoretical molecular modelling and other experimental methods like UV–vis spectroscopy, circular dichroic and thermal melting studies. Thermodynamic parameters have been obtained using the well known Van't Hoff's equation. From both theoretical and experimental findings it has been observed that it can interact effectively with CT-DNA with binding energy −7.55kcal/mol to −7.50kcal/mol.

The electrochemical reduction of perrhenate ion in non–aqueous dimethylsulfoxide solutions

The electrochemical deposition of perrenate ion in non – aqueous dimethylsulphoxide solutions of electrolytes investigation. The obtained polarization curves show that several waves are observed before electrochemical deposition of renium. The results of x-ray spectral analysis and electron microscopy allowed to determine the fact that these waves correspond to formation of a passivating film, which is formed at reduction of the solvent, on the surface of a metal substrate.

Microstructure of fibrils separated from polyacrylonitrile fibers by ultrasonic etching

Polyacrylonitrile (PAN) fiber is an important precursor fiber for high performance carbon fiber. The properties of the final carbon fiber depend strongly on the nature of the PAN fibers. The PAN fibrils were separated successfully from fibers by ultrasonic etching and were systematically investigated by field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). It is found that in certain ultrasonic etching conditions (at 75±2°C for 6 h with a frequency of 40 kHz) the PAN fibers are dissolved in the 95 wt.% aqueous dimethylsulphoxide (DMSO) solution; the fibrils consisting of numerous periodic lamellae with thickness of 30–45 nm and perpendicular to the fiber axis are separated in the 90 wt.% aqueous DMSO solution; and the fibrils with smooth surface exfoliated from the PAN fibers are obtained in the 70–90 wt.% aqueous DMSO solutions. Inner periodical structure of fibrils was observed in HRTEM, which indicates that there are different densities and two phases in fibrils. The PAN fibers are dissolved layer by layer with increasing ultrasonic etching time. The fiber surface experiences ultrasonic cleaning, selective etching, excessive etching and dissolution, and then the sublayer experiences the same process. There are numerous periodic lamellae in fibrils of nascent fibers. This means that the fibrils with lamellae are formed by orientation and crystallization in shearing field of spinning pipe and drawing stress field of coagulation bath.

Thermodynamic studies of some non-electrolytes in aqueous solutions at low temperatures

The experimental data of density ( ρ) and speed of sound ( u) in the temperature range (275.15 to 283.15) K have been obtained for aqueous solutions of di-methyl sulphoxide (DMSO), ethylene di-amine (EDA), polyethylene glycol-200 (PEG-200) and polyethylene glycol-400 (PEG-400). The specific heat ( C p ) data for aqueous solutions of DMSO, EDA, and PEG-200 have also been obtained at T = 279.15 K. The data obtained are used to calculate the derived parameters like isentropic compressibility ( β S), isothermal compressibility ( β T), apparent molar volume ( ϕ V), coefficient of thermal expansion ( α), apparent molar isentropic compressibility ( ϕ KS), and internal pressure ( P i ). The limiting values of apparent molar volume ( ϕ V ∘ ) and apparent molar isentropic compressibility ( ϕ KS ∘ ) were also obtained. From these data, the temperature coefficients of limiting properties were computed. The results obtained were interpreted in terms of solute–solvent and solute–solute interactions and structure making and structure braking abilities of the solute. The results of P i are used to discuss the extent of hydrogen bonding between solute and solvent (water).

Proton‐transfer kinetics of photoexcited 7‐hydroxy‐1‐naphthalenesulphonic acid in aqueous DMSO solutions

The monoanion of 7-hydroxy-1-naphthalenesulphonic acid (HNS) undergoes pseudo-first-order dissociation and its conjugate base undergoes second-order protonation in the lowest excited singlet state. The proton transfer kinetics in water containing dimethylsulphoxide (DMSO), up to a mole fraction of about 0.4, have been evaluated as a function of DMSO concentration. At mole fractions above 0.5 of DMSO, proton-transfer does not measurably occur. At mole fractions below 0.5, steady-state and pulsed-source fluorimetries show the rate constant for dissociation to decrease exponentially with increasing mole fraction of DMSO. This is believed to be due to penetration and disruption of the aqueous solvent cage of HNS by DMSO, resulting in impairment of the Grotthus proton-transfer mechanism. The rate of neutralization of the conjugate base by hydrogen ion is found to vary only slightly with solvent composition and depends on the bulk dielectric properties of the solvent.

The effect of solvent on the kinetics of the oxidation of 3-methyl-2,6-diphenyl-piperidin-4-one by quinolinium fluorochromate in aqueous organic media

The kinetics of the oxidation of 3-methyl-2,6-diphenyl-piperidin-4-one by quinolinium fluorochromate (QFC) have been investigated in aqueous solutions of dimethyl sulphoxide, 1,4-dioxane, tert-butanol and acetone. The influence of the added co-solvent on the reactivity were analysed in the light of various simple and multiple regression equations, viz the Laidler-Eyring, Grunwald-Winstein, Swain and Kamlet-Taft equations. The obtained results showed that the solvation phenomenon plays a dominant role on the reactivity.

Reactions of β-Sulphato-ethylsulphone Crosslinking Agent with Wool

A study was made of the application to wool of the novel chemical crosslinking agent, 2-chloro-4,6-di(-aminobenzene-4-β-sulphato-ethylsulphone)-1,3,5-triazine (XLC). The quantitative analysis of this compound was optimized using ion-pair reversed-phase HPLC, and the compound had good substantivity for wool fibers when applied from boiling aqueous dyebaths in the pH range 3 to 6. XLC was stable in boiling aqueous dimethylsulphoxide (DMSO). A 75% aqueous DMSO solution re moved the maximum amount of unfixed compound from the wool. Contrary to ex pectations, stripping at this DMSO concentration was inefficient because it gave higher apparent fixation values for higher applications of XLC, and application at higher pH values gave more extractable XLC.

Correction factors for glass electrodes in aqueous dimethylsulphoxide solutions

Correction factors for glass electrodes in aqueous dimethylsulphoxide solutions

Supramolecular catalysis: substrate phosphorylations and adenosine triphosphate synthesis with acetylphosphate catalysed by a macrocycle polyamine

In aqueous dimethyl sulphoxide solution, the macrocyclic polyamine receptor (1) catalyses the phosphorylation by acetylphosphate of phosphate containing substrates R–OP to pyrophosphates R–OPP, via the phosphoramidate intermediate (2), that acts as a molecular phosphorylating agent, converting for instance ADP into ATP.

The Henry's law constant of dimethyl sulphoxide

Abstract The partial pressure of dimethylsulphoxide (DMSO) was measured above the pure liquid and aqueous DMSO solutions at various temperatures between 7 and 35°C. These measurements yielded an expression for the dimensioned Henry's law constant of DMSO as a function of temperature: KH = 136600–1570 T°C (mol kg‐1atm‐1. The Henry's Law constant at 15 °C was measured as 1.17 ±0.02 × 105 mol kg‐1 atm‐1. Despite the solubility of DMSO in water, this result suggests that the solubility is too low for atmospheric DMSO to partition predominantly into the aqueous aerosol.

Absolute electrode potentials in dimethyl sulphoxide-water mixtures and transfer free energies of individual ions

The standard potentials of H 2|H +, M|M + (M = Li, Na, K, Rb and Cs) and Ag¦AgX (X = Cl, Br and I) electrodes in seven aqueous solutions of dimethyl sulphoxide (DMSO), containing up to 60 wt.% DMSO, have been determined from EMF measurements of cells of the type: Ag¦AgX¦MX ( m), S¦M(Hg)¦MX ( m), W¦AgX¦Ag, or a variant of it, at 25°C by our recently reported procedure. The interest, validity and general applicability of this procedure in both aqueous protic and aprotic solvents have been demonstrated. The radii of solvated cations and their solvation extent in these media have been calculated. The standard Gibbs free energies of transfer of halogen acids and alkali metal halides as well as their constituent individual ions from water to each of the DMSO-water mixtures have been also computed. The results are interpreted and discussed.

Self‐association of dimethyl sulphoxide and its dipolar interactions with water: Raman spectral studies

AbstractRaman spectra of solutions of dimethyl sulphoxide (DMSO) in carbon tetrachloride (CCl4) and water are reported for both parallel and perpendicular polarizations in the SO stretching region. The various bands obtained were subjected to Gaussian band fittings. It was observed that the bands for solutions in CCl4 may be fitted satisfactorily by considering four components and those for solutions in water may be fitted by considering five components. It is inferred that the band at ca 1070 cm−1 observed in the spectra of DMSO in CCl4 belongs to the SO stretching mode of free DMSO, whereas the two bands observed at ca 1058 cm−1 and ca 1040 cm−1 belong to out‐of‐phase and in‐phase SO stretchings of the cyclic dimer. The low‐frequency band at ca 1025 cm−1 is assigned to linear dimer/higher polymers. Aqueous solutions of DMSO show an additional band at ca 1010 cm−1 due to DMSO hydrogen‐bonded with water.

PH-jump studies at subzero temperatures on an intermediate in the reaction of xanthine oxidase with xanthine.

Xanthine oxidase is stable and active in aqueous dimethyl sulphoxide solutions of up to at least 57% (w/w). Simple techniques are described for mixing the enzyme in this solvent at--82 degrees C, with its substrate, xanthine. When working at high pH values under such conditions, no reaction occurred, as judged by the absence of e.p.r. signals. On warming to--60 degrees C, for 10 min, however, the Very Rapid molybdenum(V) e.p.r. signal was obtained. This signal did not change on decreasing the pH, while maintaining the sample in liquid nitrate reductase, caused its molybdenum(V) e.p.r. signal to change from the high-pH to the low-pH form. These findings are not compatible with the conclusions of Edmondson, Ballou, Van Heuvelen, Palmer & Massey [J. Biol. Chem. (1973) 248, 6135-6144], that the Very Rapid signal is in prototropic equilibrium with the Rapid signal, and should be important in understanding the mechanism of action of the enzyme. They emphasize the unique nature of the intermediate represented by the Very Rapid e.p.r. signal. The possible value of the pK for loss of an exchangeable proton from the Rapid signal is discussed.

Transition state enthalpies of transfer in aqueous dimethyl sulphoxide solutions. The hydroxide-catalysed racemisation ofD-α-methyl-α-phenylacetophenone

Enthalpies of solution of D-α-methyl-α-phenylacetophenone in a series of dimethyl sulphoxide–water mixtures have been measured. Taken in conjunction with the enthalpies of transfer of the hydroxide ion from a 27.8 mol% dimethyl sulphoxide–water mixture to solutions of higher dimethyl sulphoxide concentrations, and the previously published enthalpies of activation for the racemisation of the ketone, transition state enthalpies of transfer have been calculated. The results show that the increase in rate accompanying the increase in dimethyl sulphoxide concentration can be mainly accounted for by desolvation of the hydroxide ion but that desolvation of the transition state makes the increase less than it would otherwise be.

Standard potentials of M/M+(M = Li, Na, K, Rb or CS) electrodes in dimethyl sulphoxide + water mixtures at 25°C and related ion-solvent interactions in the solvents

The standard electrode potentials (sE°) of M/M+(M = Li, Na, K, Rb and Cs) electrodes in aqueous solutions of dimethyl sulphoxide (DMSO)(containing 10, 20, 40 and 60 wt. % DMSO) have been determined at 25°C from e.m.f. measurements of cells of the type: M(Hg)|MCl(m), solvent| AgCl—Ag, obtaining the activity of metals in amalgams with the help of a similar type of cell in water. The free energies of transfer of MCl, δG°t(MCl)(mole fraction scale) from water to each of these solvents computed from these values and those of sE°Ag—AgCl obtainable from the literature, rise sharply from Li+ to Na+, and fall from Rb+ to Cs+ with a maximum between Na+ and Rb+. This is considered as due to the superimposition of “soft—soft” interactions on the “electrostatic interactions” between the ions and the negative charge centres of hydrogen-bonded solvent complexes. The ΔG°t(i) values for individual ions, obtained by a method of “simultaneous extrapolation” are shown to be largely determined by the “acid-base” type ion-solvent interactions as observed in methanol + water mixtures.

Studies of Silver(I) Solvation in Binary Solvent Mixtures Containing Dimethyl Sulphoxide: II. NMR Investigations of the Shift in the Preferential Solvation of Silver Ions from Water to DMSO

AbstractAg(I) is more strongly solvated in dimethyl sulphoxide than in water. Evidence is presented from NMR and electrochemical work that Ag(I) is preferentially hydrated in dilute aqueous solutions of dimethyl sulphoxide. With increasing concentration of dimethyl sulphoxide the preferential solvation of Ag(I) is shifted from water to dimethyl sulphoxide. This behaviour is related to the characteristic properties of the binary solvent system.

Neutron Inelastic Scattering and X-Ray Studies of Aqueous Solutions of Dimethylsulphoxide and Dimethylsulphone

Molecular vibrations in solid and liquid dimethylsulphoxide (DMSO) and dimethylsulphone (DMSO2) have been measured by neutron inelastic scattering between 900–8 cm−1. Neutron spectra of the intermolecular frequencies of water molecules in aqueous solutions of perdeuterated DMSO and DMSO2 have also been measured to determine, as a function of concentration and of temperature, the influence of these compounds on the water structure. In addition, the broadening of the incident energy distribution by diffusive motions of H2O molecules has also been investigated. The similarity of intermolecular frequencies in the spectra of both the liquid and solid phases of the pure compounds shows a high degree of dipole association. In dilute aqueous solutions the DMSO and DMSO2 (hydrogenous and perdeuterated) both cause a similar enhancement and sharpening of the intermolecular frequencies of the water structure associated with a small and cooperative perturbation in the orientation of many H2O molecules. This is consistent with the x-ray radial distribution which shows a corresponding small enhancement of the peaks of pure water out to 8 Å. As the concentration of DMSO is raised, the existing water structure is broken down due to the formation of hydrogen-bonded, thermolabile, DMSO–H2O complexes. The angular and temperature dependences of the diffusively broadened incident energy distribution are both in accord with delayed or jump diffusion. At low concentrations, the residence times and the self-diffusion coefficients of H2O molecules in both DMSO and DMSO2 solutions are similar to those for pure water. At higher concentrations of DMSO, the increased formation of the hydrogen-bonded complexes causes a decrease in the self-diffusion coefficient and an increase in the delay or residence time for water molecules. Both neutron spectra and x-ray data indicate that the dipole interactions and hydrogen bonding of DMSO inhibit the formation of hexagonal ice upon freezing; this may account for the cryoprotective properties of DMSO.