Abstract
The effects of hydrogen bonds on the molecular structure of water-tetrahydrofuran (H2O–THF), water-dimethyl sulfoxide (H2O–DMSO), and water-tetrahydrofuran-dimethyl sulfoxide (H2O–THF–DMSO) in binary aqueous solutions and ternary aqueous solutions were studied using Raman spectroscopy. The results indicate that in the binary aqueous solution, the addition of THF and DMSO will generate hydrogen bonds with water molecules, resulting in changes in the peak positions of S=O bonds and C–O bonds. Compared with the binary aqueous solutions, the hydrogen bonds between DMSO and THF, and the hydrogen bonds between DMSO and H2O in the ternary aqueous solutions are competitive, and the hydrogen bond competition is susceptible to water content. In addition, the formation of hydrogen bonds will destroy the fully hydrogen-bonded water and make it change to the partially hydrogen-bonded water. By fitting the spectra into the three Gaussian components assigned to water molecules with different hydrogen bonding (HB) environments, these spectral features are interpreted by a mechanism that H2O in different solution systems has equal types of water molecules with similar HB degrees-fully hydrogen-bonded H2O (FHW) and partially hydrogen-bonded H2O (PHW). The ratio of the intensity transition from FHW to PHW is determined based on Gaussian fitting. Therefore, the variation of hydrogen bond competition can be supplemented by the intensity ratio of PHW/FHW ((IC2 + IC3)/IC1). This study provides an experimental basis for enriching the hydrogen bonding theory of multivariate aqueous solution systems.
Highlights
Water, as a simple and peculiar substance in nature, has been widely used in many fields, and has become a hot scientific topic of widespread concern [1,2,3,4,5]
Bond moves to a low wave number after adding water to DMSO, which indicates that the vibration frequency of the S=O bond decreases
By observing the change of the S=O bond in the binary mixture solution (Figure 2B), we found that its Raman peak position and peak pattern of THF–DMSO binary solution changed noticeably in the range of 1000–1100 cm−1 wave number, and was divided into two peaks
Summary
As a simple and peculiar substance in nature, has been widely used in many fields, and has become a hot scientific topic of widespread concern [1,2,3,4,5]. Taking the binary mixture of water and organic liquids as an example, the increased content of the organic liquid typically destroys the three-dimensional water–hydrogen bond, thereby changing the macroscopic properties of the solution [13]. The effect of hydrogen bonds on the surface tension of a binary mixture (acetone-water) was studied using Raman spectroscopy. There is no complete system for the law of hydrogen bond interaction in binary, ternary and multivariate aqueous solution systems. In a study on hydrogen bonding in different solution systems, we observed the change of the intensity ratio of PHW/FHW in the OH stretch region in terms of (IC2 + IC3 )/IC1. Raman spectroscopy is used to study the interaction between different substances in ternary aqueous solutions (H2O–THF–DMSO). THF, DMSO and H2O molecules, and the Raman peak position of C–O and S=O, and the hydrogen bond between THF and DMSO can cause the shift of the Raman peak position
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