Intermolecular interactions in aqueous dimethyl sulphoxide and acetic acid probed by high-pressure FTIR

摘要

The infrared spectra of DMSO/D_2O and CH_3COOD/D_2O were measured under various concentrations and pressue.The frequencies of the C-H stretching vibration bands for DMSO/D_2O mixtures increase with increasing the mole fraction of D_2O ,implying the ontraction of the C-H bonds.As the pressure was elevated to 1.5 GPa,the C-H vibrations of DMSO/D_2O were altered into four bands at approx 2927 cm~(-1),approx 2941 cm~(-1),approx 3007 cm~(-1),and approx 3025 cm~(-1).Further concentration-dependent studies indicated that the spectral features at approx2941 cm~(-1) and approx 3036 cm~(-1) arise from pressure-induced C-H…O hydrogen bonding between C-H in DMSO and oxygen atominD_2O.Ab initio calculations were performed,while the calculated results are consistent with the interpretations based onthe high-pressure infrared experiments.Analogous to DMSO/D_2O,the pressure-dependent studies on CH_3COOD/D_2O mixtures provide the evidence of the C-H…O hydrogen bonding as the pressure was elevated.