Investigating the Effect of Solvent Polarity on the IR and NMR Spectra of Acetone

Abstract

Both IR and NMR spectra of molecules are one of the most accurately measured quantities. The sensitivity of these two spectroscopic observables to the environment is investigated in the present study. Our quantum chemical calculations have shown that the bond polarization of the carbonyl bond happens due to the external electric field exerted by the solvent on the solute. This picture is used to explain the sensitivity of these two spectroscopic observables.

Further, to explain the redshift in IR there are two popular models in the literature. One is the Vibrational Stark Effect (VSE) and another is the bond polarization model. Our study shows that there can be contributions from both of these models to the IR redshifts of C=O stretch of acetone and further, the study shows that the contribution due to VSE is around one and a half times more than the bond polarization model.