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Absorption shifts in carotenoids - Influence of index of refraction and submolecular electric fields

Renge, I. and Sild, Elin LU (2011) In Journal of Photochemistry and Photobiology, A: Chemistry 218(1). p.156-161
Abstract
Most biological functions of carotenoids relate to strong visible absorption. In a quest to protein matrix effects on spectra, the shifts produced by solvent refractive index (n) and static dielectric permittivity (ε) were quantified for visible absorption maxima of β-carotene and a model compound with sharper bands, tetra-tert-butylnonaene ttbP9. The dispersive red shift that depends on optical dielectric constant n 2 is insensitive to polarity, in disagreement with previous work (H. Nagae, et al., J. Chem. Phys. 101 (1994) 6750). Small residual red shift in polar liquids obtained after subtraction of the dispersive component, obeys a static susceptibility function (ε - n 2)/(ε - n 2 + 4). Because polyenes show little inhomogeneous band... (More)
Most biological functions of carotenoids relate to strong visible absorption. In a quest to protein matrix effects on spectra, the shifts produced by solvent refractive index (n) and static dielectric permittivity (ε) were quantified for visible absorption maxima of β-carotene and a model compound with sharper bands, tetra-tert-butylnonaene ttbP9. The dispersive red shift that depends on optical dielectric constant n 2 is insensitive to polarity, in disagreement with previous work (H. Nagae, et al., J. Chem. Phys. 101 (1994) 6750). Small residual red shift in polar liquids obtained after subtraction of the dispersive component, obeys a static susceptibility function (ε - n 2)/(ε - n 2 + 4). Because polyenes show little inhomogeneous band broadening in polar solvents, the shift was assigned mainly to quadratic Stark effect, rather than to a reaction field of quadrupolar origin, proposed earlier (N. Ghoneim, P. Suppan, Spectrochim. Acta A, 51 (1995) 1043). It is highly plausible that the chromophore is polarized in short-range "edge fields", according to molecular dynamics/semiempirical simulations (F. Cichos, et al., J. Chem. Phys. 114 (2001) 6824), not in a uniform cavity field, as usually presumed. © 2011 Elsevier B.V. (Less)
Please use this url to cite or link to this publication:
author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Absorption spectrum, Carotenoid, Polyene, Quadratic Stark effect, Solvent shift
in
Journal of Photochemistry and Photobiology, A: Chemistry
volume
218
issue
1
pages
156 - 161
publisher
Elsevier
external identifiers
  • scopus:79551539286
ISSN
1873-2666
DOI
10.1016/j.jphotochem.2010.12.015
language
English
LU publication?
no
id
683fec17-1f51-4f1a-a208-435315b8c7a3 (old id 3359203)
alternative location
http://www.sciencedirect.com/science/article/pii/S1010603010005204
date added to LUP
2013-01-16 13:11:29
date last changed
2017-01-01 04:13:57
@article{683fec17-1f51-4f1a-a208-435315b8c7a3,
  abstract     = {Most biological functions of carotenoids relate to strong visible absorption. In a quest to protein matrix effects on spectra, the shifts produced by solvent refractive index (n) and static dielectric permittivity (ε) were quantified for visible absorption maxima of β-carotene and a model compound with sharper bands, tetra-tert-butylnonaene ttbP9. The dispersive red shift that depends on optical dielectric constant n 2 is insensitive to polarity, in disagreement with previous work (H. Nagae, et al., J. Chem. Phys. 101 (1994) 6750). Small residual red shift in polar liquids obtained after subtraction of the dispersive component, obeys a static susceptibility function (ε - n 2)/(ε - n 2 + 4). Because polyenes show little inhomogeneous band broadening in polar solvents, the shift was assigned mainly to quadratic Stark effect, rather than to a reaction field of quadrupolar origin, proposed earlier (N. Ghoneim, P. Suppan, Spectrochim. Acta A, 51 (1995) 1043). It is highly plausible that the chromophore is polarized in short-range "edge fields", according to molecular dynamics/semiempirical simulations (F. Cichos, et al., J. Chem. Phys. 114 (2001) 6824), not in a uniform cavity field, as usually presumed. © 2011 Elsevier B.V.},
  author       = {Renge, I. and Sild, Elin},
  issn         = {1873-2666},
  keyword      = {Absorption spectrum,Carotenoid,Polyene,Quadratic Stark effect,Solvent shift},
  language     = {eng},
  number       = {1},
  pages        = {156--161},
  publisher    = {Elsevier},
  series       = {Journal of Photochemistry and Photobiology, A: Chemistry},
  title        = {Absorption shifts in carotenoids - Influence of index of refraction and submolecular electric fields},
  url          = {http://dx.doi.org/10.1016/j.jphotochem.2010.12.015},
  volume       = {218},
  year         = {2011},
}