Importance of C*–H Based Modes and Large Amplitude Motion Effects in Vibrational Circular Dichroism Spectra: The Case of the Chiral Adduct of Dimethyl Fumarate and Anthracene
| Autor: | Giovanna Longhi, Marco Passarello, Renzo Ruzziconi, Susan Lepri, Sergio Abbate, Valentin Paul Nicu |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Circular dichroism
Anthracene adducts Dimethyl Fumarate chirality Photochemistry Vibration Isotopomers Motion chemistry.chemical_compound Fumarates Absolute configuration Physical and Theoretical Chemistry Optical rotation Conformational isomerism Anthracenes Anthracene Circular Dichroism Water Stereoisomerism vibrational circular dichroism Deuterium Crystallography chemistry Asymmetric carbon Vibrational circular dichroism Quantum Theory Thermodynamics |
| Zdroj: | The Journal of Physical Chemistry A. 118:4339-4350 |
| ISSN: | 1520-5215 1089-5639 |
| DOI: | 10.1021/jp502544v |
| Popis: | The role played by the C*-H based modes (C* being the chiral carbon atom) and the large amplitude motions in the vibrational absorption (VA) and vibrational circular dichroism (VCD) spectra is investigated. The example of an adduct of dimethyl fumarate and anthracene, i.e., dimethyl-(+)-(11R,12R)-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylate, and two deuterated isotopomers thereof specially synthesized for this goal, are considered. By comparing the experimental and DFT calculated spectra of the undeuterated and deuterated species, we demonstrate that the C*-H bending, rocking, and stretching modes in the VA and VCD spectra are clearly identified in well defined spectroscopic features. Further, significant information about the conformer distribution is gathered by analyzing the VA and VCD data of both the fingerprint and the C-H stretching regions, with particular attention paid to the band shape data. Effects related to the large amplitude motions of the two methoxy moieties have been simulated by performing linear transit (LT) calculations, which consists of varying systematically the relative positions of the two methoxy moieties and calculating VCD spectra for the partially optimized structures obtained in this way. The LT method allows one to improve the quality of calculated spectra, as compared to experimental results, especially in regard to relative intensities and bandwidths. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|