Solvent Effects on Raman Optical Activity Spectra Calculated Using the Polarizable Continuum Model

Abstract

The integral equation formulation of the polarizable continuum model (IEFPCM) has been extended to the calculation of solvent effects on vibrational Raman optical activity spectra. Gauge-origin independence of the differential scattering intensities of right and left circularly polarized light is ensured through the use of London atomic orbitals. Density functional theory (DFT) calculations have been carried out for bromochlorofluoromethane, methyloxirane, and epichlorhydrin. The results indicate that solvent effects on the ROA differential scattering intensities can be substantial, and vary in sign and magnitude for different vibrational modes. It is demonstrated that both direct and indirect effects are important in determining the total solvent effects on the ROA differential scattering intensities. Local field effects are shown to be in general small, whereas electronic nonequilibrium solvation has a profound effect on the calculated solvent effects compared to an equilibrium solvation model. For molecules with several conformations, the changes in the relative stability of the different conformers also lead to noticeable changes in the ROA spectra.

Where does the Raman optical activity of [Rh(en)3]3+come from? Insight from a combined experimental and theoretical approach

“…32,33 The calculations were performed with the B3LYP hybrid exchange-correlation functional [34][35][36] because of its good performance for ROA calculations 25,26,[37][38][39][40] . In order to have a good description of the dispersion interactions, we employed the D2 dispersion correction of Grimme.…”

“…The study combines the measurement of Raman and ROA spectra and their analyses based on quantum chemical calculations. Because the solutesolvent interactions are likely to significantly influence the recorded spectra 25,26 , solvents effects were included in the calculations. In a first approach, an implicit solvation model was used.…”

Cavity field effects within a polarizable continuum model of solvation: Application to the calculation of electronic circular dichroism spectra of R‐(+)‐3‐methyl‐cyclopentanone

“…The formulation of CF effects within the polarizable continuum model (PCM) [16,17] for many spectroscopic [18][19][20][21][22] properties, birefringences [23,24], and response properties [25][26][27] has been so far the subject of many studies involving the present authors. Recent reviews of such a matter can be found in Refs.…”

First-Principles Approach to Vibrational Spectroscopy of Biomolecules

“…As far as the calculation of VCD and ROA spectra is concerned, solvent effects can become even more important than for techniques which are not sensitive to chirality, since not only the relative magnitudes, but also the signs of vibrational bands may change in different solvents [156,157], either indirectly Experimental ROA spectrum of poly-l-alanine in 30% dichloroacetic acid/70% CHCl 3 (reproduced from data presented in [127]). Top right: Symbolical representation of (all-S)-deca-alanine.…”

“…In [156] for example, solvent effects on VCD spectra of proline, modeled by a combination of the integral equation formulation of the polarizable continuum model (PCM) and explicit water molecules, are found to influence the relative energies of different conformations considerably, whereas the structural parameters are quite invariant to solvent effects. A complementary study has been carried out for ROA [157], employing the same PCM version but no explicit solvent molecules, which points out the importance of considering the solvent influence on both the vibrational normal modes and the property tensors. It has been reported in previous studies that the explicit consideration of water molecules in the first solvation shell of solvated alanine improves ROA results considerably in combination with an Onsager continuum model [158].…”