Contribution of relaxation and chemical shift results to the elucidation of the structure of the water-DMSO liquid system

Abstract

The contribution of intramolecular vibrations to the observed structure of liquid water J. Chem. Phys. 82, 5289 (1985); 10.1063/1.448606 Ultrasonic measurements and liquid structure of DMSO-water mixture Proton spin-lattice relaxation times (T 1) of water and dimethyl sulfoxide (DMSO) in H20-DMSO (I), H 2 0-DMSO-d 6 (II), and D 2 0-DMSO (IV) systems at 9.8, 18.7,29.9, and 41.4°C exhibited minima near 0.65 mole fraction of water (X H,O)' The depth of the minimum, relative to T 1 values at higher and lower X H,O' increased as the temperature was lowered. The intramolecular contribution to the relaxation of DMSO protons was always greater than the intermolecular DMSO-DMSO contribution and the former showed a minimum at X D 0::::0.6 as compared with the latter's minimum at X D,0::::0.4-0.6. There is almost no contrib~tion to water proton T 1 from the interaction of water protons-DMSO protons in the DMSO·rich mixtures, while this contribution is rather significant in the DMSO·poor mixtures. The proton chemical shifts of water with reference to DMSO protons (over a temperature range of -60-45'C) moves to higher fields with rising temperatures, and this temperature dependence is affected considerably by the changes in composition. All these experimental results suggest the presence of strong intermolecular interactions between water and DMSO molecules that contribute to the "structuring" of this binary mixture. The structure of this liquid system is very sensitive to composition and temperature.In this work the dynamic liquid structure of DMSOwater mixtures was investigated by measuring T 1 , T 2 , and chemical shift values of the protons of both compo-

Polarizability anisotropy relaxation in pure and aqueous dimethylsulfoxide

“…4 -14 The prevailing view is that most of these effects are associated with DMSO's strong hydrophilic nature, which leads to the formation of stoichiometrically well-defined DMSO-water aggregates, with the concomitant formation of a hydrogen bond network and pronounced structural microheterogeneities. 10,[15][16][17][18] No evidence of hydrophobic association between DMSO molecules, as suggested by early experiments, 19,20 has been found by neutron diffraction analyses. 17 More recently, DMSO-water systems have been studied by experimental techniques such as time-resolved Kerr spectroscopy, 21 quasi-elastic neutron scattering, 22,23 timeresolved fluorescence upconversion spectroscopy, 23 and mass spectrometry, 24 devised to investigate molecular clustering.…”

Concentration‐Dependent Hydrogen‐Bonding Effects on the Dimethyl Sulfoxide Vibrational Structure in the Presence of Water, Methanol, and Ethanol

“…[10] At this mixing ratio a viscosity maximum is reached and an extended reordering process takes place, [10] thus leading to different diffusion dynamics, hindered rotation, and the absence of stable HBs between DMSO and water. [11][12][13] Along with the mentioned nonideal mixing behavior, a local heterogeneity of DMSO/ water mixtures has been discovered by both experimental techniques [14] and molecular dynamics simulation methods. [15][16][17] Aside from the molecular formations of DMSO molecules, the origin of inter-and intramolecular interactions leadThe effects of hydrogen bonding between dimethyl sulfoxide (DMSO) and the co-solvents water, methanol, and ethanol on the symmetric and antisymmetric CSC stretching vibrations of DMSO are investigated by means of Raman spectroscopy.…”

“…[43] Furthermore, this is in concert with the main cluster type found at high water mole fractions, which consists of icelike hexagonal water structures each stabilized by two DMSO molecules leading to a highly ordered mixture. [12] Therefore, one can state that the higher the slopes the more significant the blue shift and eventually the stronger the bond strengthening due to intermolecular interactions between water and DMSO. Of course, as mentioned in the Introduction, effects such as rehybridization or the increasing electric field of water make their contribution to the steeper course of the curve.…”

Orientation of Water Molecules around Small Polar and Nonpolar Groups in Solution: A Neutron Diffraction and Computer Simulation Study

“…[13][14][15] Inelastic neutron scattering and X-ray diffraction on this system have also been reported. 16 The interpretation of those data in terms of water structure tends to be qualitative: the results for the dilute aqueous solutions of DMSO have been interpreted 10,16 as indicating that the presence of DMSO enhances the water hydrogen bond network, due to the hydrophobic hydration of the methyl groups.…”