Formation of hydrogen bonds and vibrational processes in dimethyl sulfoxide and its aqueous solutions: raman spectroscopy and ab initio calculations

The intermolecular interaction in dimethyl sulfoxide (DMSO), which is a strong solvent, and its manifestation in vibrational spectra are studied by means of Raman spectroscopy and ab initio calculations. The optimal structure and vibrational spectra of DMSO monomer, dimer, and trimer, as well as complexes of DMSO with water molecules, are calculated, and the potential energy distribution (PED) analysis is carried out. In the Raman spectra of DMSO and its water solutions, a red shift of the S=O stretching band due to the conventional hydrogen bonding and a blue shift of the C-H stretching band due to non-classical hydrogen bonding are detected. The MEP surfaces (changes in the charge distribution) of DMSO monomer, dimer, and DMSO-water cluster are plotted.