Investigation of hydrogen bonding in Water/DMSO binary mixtures by Raman spectroscopy

Raman spectra of water/dimethyl sulfoxide (DMSO) mixtures have been observed at room temperature and atmospheric pressure. We find that the Raman peaks corresponding to the symmetric and asymmetric O-H stretching vibration mode of water rapidly move to lower wavenumber with increasing DMSO concentration. These results indicate that the strong hydrogen bond between DMSO-water complexes helps to strengthen the tetrahedral structure of water when the volume fraction of DMSO is less than 0.6. Moreover, the blue/red shifts of SO and C-H are obvious when the concentration of DMSO reaches 0.6, which may be due to changes in the structure of the DMSO-water complex. Furthermore, the frequency shift of the C-H group indicates that the non-polar methyl group of DMSO forms a hydrophobic hydrated structure. Finally, the frequency shift of the Raman peaks of SO and C-H exhibited a highly consistent concentration dependence due to the cooperation effect of the C-H⋯O with the O-H⋯OS.