Infrared spectroscopy of isolated molecules having a dimethyl group in CCl4

초록

The in-situ inclusion of acetone, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), and 2-propanol into carbon tetrachloride (CCl4) were investigated by infrared vibrational spectroscopy. IR spectra in the CH stretch region were very different although the dimethyl group responsible for this region of the spectra is common for all these molecules. The difference between the spectra was explained in terms of the DFT calculations of the monomer molecules. The spectra changed appreciably in the in-situ inclusion process for acetone and 2-propanol, while did not change for DMSO and DMF, aside from an increase proportional to increased concentration. The structures of the molecules in the time series were verified by quantum chemical calculations of monomers and dimers for these molecules, and their vibrational spectra were also calculated. The results indicate that DMSO and DMF having large molecular dipole moments are included as a dimer (or multimer) into the CCl4 matrix due to the strong dipole interaction, while the other molecules first enter the CCl4 phase as monomers and take multimer structures afterwards.

키워드