Theoretical Study of the Anisotropy Spectra of the Valine Zwitterion and Glyceraldehyde
Résumé
The absorption, electric circular dichroism, and anisotropy spectra of the L-valine zwitterion and D-glyceraldehyde are calculated by time-dependent density functional theory with the M06-2X and B3LYP functionals. It is found that the absorption and ECD spectra from TDDFT/M06-2X agree well with the experimental result measured from the L-valine amorphous film. Moreover, the theoretical calculation reproduces all three major peaks observed on the experimental anisotropy spectra. For D-glyceraldehyde, the TDDFT/M06-2X calculation indicates the excitation wavelengths of the first excited state of 32 stable conformers distribute from 288 to 320 nm, giving rise to two ECD peaks centered at 288 nm and 335 nm with the opposite sign. Both the anisotropy spectra of the L-valine zwitterion and D-glyceraldehyde exhibit a high negative peak in the ultraviolet (UV) region, which may lead to enantioenrichment of them by exposing the racemic films to the circular polarized light.
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