Ab initio studies on structure and vibrational spectra of ubiquinone and its radical anion

Balakrishnan, Gurusamy and Mohandas, Pothukattil and Umpathy, Siva (1997) Ab initio studies on structure and vibrational spectra of ubiquinone and its radical anion. In: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 53 (10). pp. 1553-1561.

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Abstract

The structure and vibrational spectra of ubiquinone (UQ) and its radical anion (UQ) has been studied by ab initio MO calculations. For UQ, as in the case of its unsubstituted counterpart p-benzoquinone (p-BQ), calculations show extensive coupling between the C=C and C=O stretching local modes giving rise to four frequencies in $1600-1750 cm^{-1}$ region. However, the vibrational structure of these modes are found to be different from that of p-BQ because of a near complete decoupling between the two C=O stretching local modes. For $UQ^{\cdot-}$, these frequencies are shifted significantly to lower wave numbers. The ring C-C stretching frequencies show noticeable increase. These shifts in the frequencies are explained on the basis of the structural changes associated with the reduction of UQ to $UQ^{\cdot-}$. Assignment of the vibrational frequencies are made on the basis of PEDs, isotopic shifts and comparison with the experimental results.

Item Type: Journal Article Copyright of this article belongs to Elsevier. Ubiquinone;Vibrational spectra;Ab initio;Radical anion Division of Chemical Sciences > Inorganic & Physical Chemistry 11 Apr 2007 19 Sep 2010 04:37 http://eprints.iisc.ernet.in/id/eprint/10650