The Infrared and Vibrational Circular Dichroism Spectra of (S)-Proline in Water: an ab initio study

摘要

As main subject of the talk, the infrared and vibrational circular dichroism of proline in water solution are investigated ab initio employing density functional theory and the integral equation formalism (IEF) version of the polarizable continuum model (PCM). Three solvent models are exploited to evaluate solvent effects in the 1000-2000 cm~(-1) frequency range: a pure implicit continuum approach, a pure explicit model (limited to three solvent molecules) and a combined specific/continuum approach. Effects on spectra arising from different protonation states (neutral, zwitterionic, cationic and anionic are analyzed. The effect of specific (hydrogen bond) solute-solvent interactions, arising due to the unique features of the aqueous environment, and which can only partially be estimated by a pure continuum approach is accounted for by introducing cluster structures including explicitly three water molecules arranged around the proline moiety.