Electronic states of emodin and its conjugate base

Synchrotron linear dichroism spectroscopy and quantum chemical calculations

Son Chi Nguyen, Bjarke Knud Vilster Hansen, Søren Vrønning Hoffmann, Jens Spanget-Larsen

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

The electronic transitions of emodin (1,3,8-trihydroxy-6-methyl-9,10-anthraquinone, E) and its conjugate base (3-oxido-6-methyl-1,8-dihydroxy-9,10-anthraquinone, Ecb) were investigated by UV-Vis linear dichroism (LD) spectroscopy on molecular samples aligned in stretched poly(vinylalcohol). The experiments in the UV region were performed with synchrotron radiation, thereby obtaining significantly improved signal to noise ratio compared with traditional technology. The LD spectra provided information on the polarization directions of the observed transitions, thereby leading to resolution of otherwise overlapping, differently polarized transitions. The investigation was supported by PCM-TD-DFT calculations; a mixed discrete/continuum solvation model was applied in the case of the strongly solvated Ecb anion. The calculations led to excellent agreement with the observed transitions, resulting in the assignment of at least 7 excited electronic states in the region 15000 - 50000 cm-1 for each species. A recent assignment of the absorption spectrum of E to a superposition of contributions from 9,10- and 1,10-anthraquinoid tautomeric forms was not supported by the results of the present investigation.
OriginalsprogEngelsk
TidsskriftChemical Physics
Vol/bind352
Udgave nummer1-3
Sider (fra-til)167-174
Antal sider8
ISSN0301-0104
DOI
StatusUdgivet - 2008

Citer dette

Nguyen, Son Chi ; Hansen, Bjarke Knud Vilster ; Hoffmann, Søren Vrønning ; Spanget-Larsen, Jens. / Electronic states of emodin and its conjugate base : Synchrotron linear dichroism spectroscopy and quantum chemical calculations. I: Chemical Physics. 2008 ; Bind 352, Nr. 1-3. s. 167-174.
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title = "Electronic states of emodin and its conjugate base: Synchrotron linear dichroism spectroscopy and quantum chemical calculations",
abstract = "The electronic transitions of emodin (1,3,8-trihydroxy-6-methyl-9,10-anthraquinone, E) and its conjugate base (3-oxido-6-methyl-1,8-dihydroxy-9,10-anthraquinone, Ecb) were investigated by UV-Vis linear dichroism (LD) spectroscopy on molecular samples aligned in stretched poly(vinylalcohol). The experiments in the UV region were performed with synchrotron radiation, thereby obtaining significantly improved signal to noise ratio compared with traditional technology. The LD spectra provided information on the polarization directions of the observed transitions, thereby leading to resolution of otherwise overlapping, differently polarized transitions. The investigation was supported by PCM-TD-DFT calculations; a mixed discrete/continuum solvation model was applied in the case of the strongly solvated Ecb anion. The calculations led to excellent agreement with the observed transitions, resulting in the assignment of at least 7 excited electronic states in the region 15000 - 50000 cm-1 for each species. A recent assignment of the absorption spectrum of E to a superposition of contributions from 9,10- and 1,10-anthraquinoid tautomeric forms was not supported by the results of the present investigation.",
keywords = "Hydroxy-anthraquinones, Electronic transitions, Polarization directions, Transition moments, Time-Dependent Density Functional Theory (TD-DFT), Solvation models",
author = "Nguyen, {Son Chi} and Hansen, {Bjarke Knud Vilster} and Hoffmann, {S{\o}ren Vr{\o}nning} and Jens Spanget-Larsen",
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Electronic states of emodin and its conjugate base : Synchrotron linear dichroism spectroscopy and quantum chemical calculations. / Nguyen, Son Chi; Hansen, Bjarke Knud Vilster; Hoffmann, Søren Vrønning; Spanget-Larsen, Jens.

I: Chemical Physics, Bind 352, Nr. 1-3, 2008, s. 167-174.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Electronic states of emodin and its conjugate base

T2 - Synchrotron linear dichroism spectroscopy and quantum chemical calculations

AU - Nguyen, Son Chi

AU - Hansen, Bjarke Knud Vilster

AU - Hoffmann, Søren Vrønning

AU - Spanget-Larsen, Jens

PY - 2008

Y1 - 2008

N2 - The electronic transitions of emodin (1,3,8-trihydroxy-6-methyl-9,10-anthraquinone, E) and its conjugate base (3-oxido-6-methyl-1,8-dihydroxy-9,10-anthraquinone, Ecb) were investigated by UV-Vis linear dichroism (LD) spectroscopy on molecular samples aligned in stretched poly(vinylalcohol). The experiments in the UV region were performed with synchrotron radiation, thereby obtaining significantly improved signal to noise ratio compared with traditional technology. The LD spectra provided information on the polarization directions of the observed transitions, thereby leading to resolution of otherwise overlapping, differently polarized transitions. The investigation was supported by PCM-TD-DFT calculations; a mixed discrete/continuum solvation model was applied in the case of the strongly solvated Ecb anion. The calculations led to excellent agreement with the observed transitions, resulting in the assignment of at least 7 excited electronic states in the region 15000 - 50000 cm-1 for each species. A recent assignment of the absorption spectrum of E to a superposition of contributions from 9,10- and 1,10-anthraquinoid tautomeric forms was not supported by the results of the present investigation.

AB - The electronic transitions of emodin (1,3,8-trihydroxy-6-methyl-9,10-anthraquinone, E) and its conjugate base (3-oxido-6-methyl-1,8-dihydroxy-9,10-anthraquinone, Ecb) were investigated by UV-Vis linear dichroism (LD) spectroscopy on molecular samples aligned in stretched poly(vinylalcohol). The experiments in the UV region were performed with synchrotron radiation, thereby obtaining significantly improved signal to noise ratio compared with traditional technology. The LD spectra provided information on the polarization directions of the observed transitions, thereby leading to resolution of otherwise overlapping, differently polarized transitions. The investigation was supported by PCM-TD-DFT calculations; a mixed discrete/continuum solvation model was applied in the case of the strongly solvated Ecb anion. The calculations led to excellent agreement with the observed transitions, resulting in the assignment of at least 7 excited electronic states in the region 15000 - 50000 cm-1 for each species. A recent assignment of the absorption spectrum of E to a superposition of contributions from 9,10- and 1,10-anthraquinoid tautomeric forms was not supported by the results of the present investigation.

KW - Hydroxy-anthraquinones

KW - Electronic transitions

KW - Polarization directions

KW - Transition moments

KW - Time-Dependent Density Functional Theory (TD-DFT)

KW - Solvation models

U2 - 10.1016/j.chemphys.2008.06.007

DO - 10.1016/j.chemphys.2008.06.007

M3 - Journal article

VL - 352

SP - 167

EP - 174

JO - Chemical Physics

JF - Chemical Physics

SN - 0301-0104

IS - 1-3

ER -