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Bisignate resonance Raman optical activity: a pseudo breakdown of the single electronic state model of RROA?
Author(s) -
Zajac Grzegorz,
Kaczor Agnieszka,
ChruszczLipska Katarzyna,
Dobrowolski Jan Cz.,
Baranska Malgorzata
Publication year - 2014
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.4563
Subject(s) - conformational isomerism , raman spectroscopy , astaxanthin , raman optical activity , density functional theory , chemistry , resonance (particle physics) , molecular physics , spectrum (functional analysis) , population , basis set , molecule , nuclear magnetic resonance , computational chemistry , atomic physics , physics , optics , quantum mechanics , organic chemistry , food science , demography , sociology , carotenoid
Raman optical activity (ROA) spectra were calculated for a set of conformers of astaxanthin, which is a non‐rigid molecule exhibiting strong resonance enhancement in the visible range. Single electronic state theory of the Resonance ROA (RROA) predicts the spectrum to be monosigned. For astaxanthin, it appeared that some of the conformers exhibit different sign of the bands than the other conformers. As a result, the conformer population averaged spectrum of astaxanthin can exhibit both signs of the bands, or be monosigned depending on which conformers are dominating, that reflects a departure from the single electronic state approximation. Moreover, use of different basis sets and/or density functional theory (DFT) functionals results in different conformer populations, thus yielding again either monosigned ROA spectrum or with bands of both signs. Consequences of these two findings for the astaxanthin RROA spectrum are discussed. Copyright © 2014 John Wiley & Sons, Ltd.