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Title
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Raman and ROA spectra of (-)- and (+)-2-Br-hexahelicene : experimental and DFT studies of a -conjugated chiral system
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Author
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Abstract
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| The Raman optical activity (ROA) spectra of both enantiomers of 2-Br-hexahelicene in chloroform solution have been measured in the range 1700-300 cm(-1). Density functional theory (DFT) calculations accurately reproduce the observed features. The most intense ROA features are also the most intense Raman features, in the region 1350-1400 cm(-1), and correspond to the so-called D-modes, which play a major role in coronene and other PAHs (polycyclic aromatic hydrocarbons). Together with a detailed analysis of the normal mode structure, the polarizability tensors for the intense Raman features are investigated and related to the principal characteristics of helicene systems, namely, chirality and pi-conjugation. Through electron-phonon coupling analysis, we propose a mechanism that justifies the intense ROA signals. |
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Language
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English
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Source (journal)
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The journal of physical chemistry : B : condensed matter, materials, surfaces, interfaces and biophysical. - Washington, D.C.
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Publication
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Washington, D.C.
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2013
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ISSN
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1520-6106
1520-5207
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DOI
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10.1021/JP312425M
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Volume/pages
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117
:7
(2013)
, p. 2221-2230
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ISI
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000315432200027
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Full text (Publisher's DOI)
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