Features of light scattering in aqueous solutions of dimethyl sulfoxide

The water-dimethyl sulfoxide (DMSO) system was studied by means of static light scattering in the concentration range of 0 to 60 mol % DMSO at 20 and 50°C. In the concentration range of 10 mol % DMSO, an abnormal maximum of scattered light was detected, the intensity of which decreases with an increase of temperature. The formation of this maximum is related to hydrophobic effects in the system under study and the existence of an unattainable critical point of delayering. Temperature inversion of light scattering intensity was detected at ∼14 mol % DMSO; at higher concentrations of DMSO, the intensity at 50°C is notably higher than at 20°C (due to the increase in the concentration’s degree of fluctuation upon an increase in temperature); at 60 mol % DMSO, intensities of scattered light at 20 and 50°C almost coincide. The apparent molar volumes of DMSO in solutions were calculated from the published data on density in the temperature range of 5 to 50°C. The minima of these values from 10 to 15 mol % DMSO (i.e., in the range of the abnormal maximum of scattered light) were obtained. The manifestation of hydrophobic effects in aqueous solutions of amphiphilic molecules is explained using the example of the DMSO-H₂O system.     

Dielectric spectrum and structure of aqueous solutions of dimethyl sulfoxide

Russian Chemical Bulletin - Frequency measurements of aqueous solutions of dimethyl sulfoxide (DMSO) were carried out in the range of 0.5-36.5 GHz at temperatures 293-323 K. Relaxation spectra were...     

Molecular interactions between benzimide trichloride (Hoechst 33258) and DNA in dimethyl sulfoxide aqueous solutions, according to spectroscopy data

Interaction between benzimide (Hoechst 33258, H33258) and calf thymus DNA in aqueous dimethyl sulfoxide is investigated by means of UV-Vis and fluorescence spectroscopy at a constant ratio (r) of the number of H33258 molecules and DNA base pairs. Melting curves of the DNA-H33258 complex are obtained from the temperature dependences of the normalized optical density and fluorescence intensity, and the melting temperatures of the complex are determined. It is shown that adding dimethyl sulfoxide (DMSO) lowers the complex’s melting temperature. It is concluded that a long wavelength shift of the fluorescence spectra occurs when the temperature is raised.     

Reaction of π-allylirontric arbonylhalides with dimethyl sulfoxide

Conclusions Dimethyl sulfoxide readily decomposes -allylirontricarbonylhalides with the evolution of 1,5-hexadiene and carbon monoxide and formation of sulfoxide complexes of composition [(CH₃)₂SO]₅FeX₂. In the complexes isolated coordination is through the oxygen of the sulfoxide group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 192–194, January, 1968.We thank L. I. Denisovich for the polarographic studies.     

Solvation effects in human serum albumin radiolysis in the presence of dimethyl sulfoxide

PMR and electrophoresis have been applied to examine hydration changes in protein molecules due to the presence of the electron donor dimethylsulfoxide DMSO, which influences the radiolysis of human serum albumin HSA. The reactions of aqueous HSA with added DMSO show that the DMSO on the one hand acts as a protector, which prevents the formation of low-molecular protein forms on reaction with hydroxyl radicals, and on the other alters the protein hydration, which facilitates thiol-di-sulfide exchange, which leads to oligomers.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 1, pp. 107–111, January–February, 1990.     

Multibubble sonoluminescence of Tb3+ ion in aqueous solutions of dimethyl sulfoxide

The intensity and spectra of multibubble sonoluminescence of TbCl₃ solutions in water-DMSO mixtures saturated with air and argon are studied. The spectra represent the superposition of the characteristic glow of Tb³⁺ ions and the continuum of emission of electronically excited products of solvent sonolysis (with H₂O*, OH*, and SO₂* as main emitters). Abnormal action of DMSO and sulfur dioxide on the characteristic luminescence of Tb³⁺ ions during sonolysis of aqueous solutions is revealed. These additives enhance the sonoluminescence of water to different extent, quench the sonoluminescence of Tb³⁺, and differently influence the photoluminescence quantum yield of this ion (DMSO acts as activator, whereas SO₂ acts as quencher). Sulfur dioxide quenches the sonoluminescence of Tb3+ much more efficiently than the photoluminescence of Tb³⁺. The abnormal effect of DMSO on sonoluminescence is most probably due to the quenching action of sulfur dioxide formed during sonolysis of DMSO on Tb³⁺* ions in cavitation bubbles.     

Preferential solvation of lysozyme by dimethyl sulfoxide in binary solutions of water and dimethyl sulfoxide

To reveal the denaturation mechanism of lysozyme by dimethyl sulfoxide (DMSO), thermal stability of lysozyme and its preferential solvation by DMSO in binary solutions of water and DMSO was studied by differential scanning calorimetry (DSC) and using densities of ternary solutions of water (1), DMSO (2) and lysozyme (3) at 298.15 K. A significant endothermic peak was observed in binary solutions of water and DMSO except for a solution with a mole fraction of DMSO (x ₂) of 0.4. As x ₂ was increased, the thermal denaturation temperature T _m decreased, but significant increases in changes in enthalpy and heat capacity for denaturation, ΔH _cal and ΔC _p, were observed at low x ₂ before decreasing. The obtained amount of preferential solvation of lysozyme by DMSO (∂g ₂/∂g ₃) was about 0.09 g g⁻¹ at low x ₂, indicating that DMSO molecules preferentially solvate lysozyme at low x ₂. In solutions with high x ₂, the amount of preferential solvation (∂g ₂/∂g ₃) decreased to negative values when lysozyme was denatured. These results indicated that DMSO molecules do not interact directly with lysozyme as denaturants such as guanidine hydrochloride and urea do. The DMSO molecules interact indirectly with lysozyme leading to denaturation, probably due to a strong interaction between water and DMSO molecules.     

Complex formation of silver(I) with glycinate ion in aqueous ethanol and dimethyl sulfoxide solutions

The complex formation reaction of silver(I) with glycinate ion in aqueous ethanol and dimethyl sulfoxide solutions of variable compositions was studied by potentiometric titration at 298 K. The stabilities of Ag(I) glycinate complexes were found to increase with the increasing content of the organic cosolvent. The contribution of ΔG° of the reagent resolvation to the change in the Gibbs energy of the complex formation reaction was estimated using the literature data. The change in the ligand solvate state was shown to give the main contribution to the stability of the title complexes in water-organic solvents.