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Photochem Photobiol Sci. 2005 Mar;4(3):298-303. Epub 2005 Jan 20.

Comparative study of the photophysical properties of indoprofen photoproducts in relation with their DNA photosensitizing properties.

Author information

  • 1Laboratoire des Interactions Moleculaires et Reactivite Chimique et Photochimique, UMR 5623 au CNRS, Universite Paul Sabatier, 118, route de Narbonne, 31062, Toulouse cedex 4, France.

Abstract

The photophysical properties of indoprofen photoproducts have been examined in various solvents by absorbance and emission spectroscopies in relation with their photosensitizing properties. The photophysical properties of 2-[4-(1-hydroxy)ethylphenyl]isoindolin-1-one (HOINP) and 2-(4-ethylphenyl)isoindolin-1-one (ETINP) are typical of a singlet excited state when the ones of 2-(4-acetylphenyl)isoindolin-1-one (KINP) are based on its triplet excited state according to previous work. The effect of solvent polarity on the absorption and fluorescence properties of HOINP and ETINP has been investigated as a function of Delta f, the Lippert solvent polarity parameter. A solvatochromic effect, function of the polarity region, has been observed for both photoproducts due to a change in the dipole moment of the compound upon excitation. In low-polarity regions, the excited state dipole moment of HOINP undergoes only a moderate increase (11.5 D) as compared to the dipole moment of the ground state (4.5 D) suggesting that the fluorescence arises from the locally excited state while in high-polarity regions it is strongly increased (42.9 D), which can imply that the emission takes place from a charge transfer state. In the case of ETINP, it would seem that the emitting state is rather a charge transfer state whatever the region is (16.9 and 31.8 D for the calculated excited-state dipole moments in the low and high-polarity regions, respectively). HOINP and ETINP do not produce thymine dimers by photosensitization but induce photooxidative damage via an electron transfer mechanism.

PMID:
15738999
[PubMed - indexed for MEDLINE]
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