Details

Autor(en) / Beteiligte

• Katsyuba, Sergey A.
• Gerasimova, Tatiana P.
• Spicher, Sebastian
• Bohle, Fabian
• Grimme, Stefan

Titel

Computer‐aided simulation of infrared spectra of ethanol conformations in gas, liquid and in CCl4 solution

Ist Teil von

• Journal of computational chemistry, 2022-02, Vol.43 (4), p.279-288

Ort / Verlag

Hoboken, USA: John Wiley & Sons, Inc

Erscheinungsjahr

2022

Quelle

Wiley Online Library All Journals

Beschreibungen/Notizen

• The recently developed efficient protocol combining implicit and explicit, accurate quantum‐mechanical modeling of the condensed state (Katsyuba et al., J. Chem. Phys. 155, 024507 [2021]) is used to describe the IR spectra of liquid ethanol and its solutions in CCl4. The relative abundance of the anti and gauche conformers of ethanol is shown to increase from ~40:60 in the gas phase to ~55:45 in the liquid phase. In spite of a moderate impact of media effects on the conformational composition of the liquid, the solvent strongly influences vibrational frequencies, IR intensities, and normal modes of each conformer, producing qualitatively different spectra compared to the gas phase and CCl4 solution. Further, these solvent effects affecting IR frequencies and intensities depend not only on the conformation of the solvated molecule but also on the solvating species. Nevertheless, vibrational frequencies of anti and gauche conformers of liquid ethanol and its several isotopomers practically coincide with each other. Convenient liquid‐state conformational markers in the fingerprint region of IR spectra are revealed for the hydroxyl‐deuterated species: CH3CH2OD, CH3CHDOD, CH3CD2OD, and CD3CD2OD. The protocol for the calculation of infrared spectra in the condensed phase (which combines the determination of conformer populations using implicit solvation model, the automatic construction of solvent clusters using semi‐empirical methods, and the Density Functional Theory calculation of the spectra using these explicitly solvated cluster models) is applied to ethanol, with a focus on distinguishing spectral signatures of the anti and gauche conformers. The computations accurately reproduce experimental spectra and their changes in the different phases.