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Role of Solvent, pH, and Molecular Size in Excited-State Deactivation of Key Eumelanin Building Blocks: Implications for Melanin Pigment Photostability.

Gauden, Magdalena LU ; Pezzella, A; Panzella, L; Neves-Petersen, M; Skovsen, E; Petersen, S; Mullen, K; Napolitano, A; d'Ischia, M and Sundström, Villy LU (2008) In Journal of the American Chemical Society 130(50). p.17038-17043
Abstract
Ultrafast time-resolved fluorescence spectroscopy has been used to investigate the excited-state dynamics of the basic eumelanin building block 5,6-dihydroxyindole-2-carboxylic acid (DHICA), its acetylated, methylated, and carboxylic ester derivatives, and two oligomers, a dimer and a trimer in the O-acetylated forms. The results show that (1) excited-state decays are faster for the trimer relative to the monomer; (2) for parent DHICA, excited-state lifetimes are much shorter in aqueous acidic medium (380 ps) as compared to organic solvent (acetonitrile, 2.6 ns); and (3) variation of fluorescence spectra and excited-state dynamics can be understood as a result of excited-state intramolecular proton transfer (ESIPT). The dependence on the... (More)
Ultrafast time-resolved fluorescence spectroscopy has been used to investigate the excited-state dynamics of the basic eumelanin building block 5,6-dihydroxyindole-2-carboxylic acid (DHICA), its acetylated, methylated, and carboxylic ester derivatives, and two oligomers, a dimer and a trimer in the O-acetylated forms. The results show that (1) excited-state decays are faster for the trimer relative to the monomer; (2) for parent DHICA, excited-state lifetimes are much shorter in aqueous acidic medium (380 ps) as compared to organic solvent (acetonitrile, 2.6 ns); and (3) variation of fluorescence spectra and excited-state dynamics can be understood as a result of excited-state intramolecular proton transfer (ESIPT). The dependence on the DHICA oligomer size of the excited-state deactivation and its ESIPT mechanism provides important insight into the photostability and the photoprotective function of eumelanin. Mechanistic analogies with the corresponding processes in DNA and other biomolecules are recognized. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of the American Chemical Society
volume
130
issue
50
pages
17038 - 17043
publisher
The American Chemical Society
external identifiers
  • wos:000263320400043
  • pmid:19007162
  • scopus:58049208368
ISSN
1520-5126
DOI
10.1021/ja806345q
language
English
LU publication?
yes
id
eee2c984-85f7-481a-a41e-857188511f70 (old id 1271475)
date added to LUP
2009-01-22 16:01:58
date last changed
2017-11-05 03:37:21
@article{eee2c984-85f7-481a-a41e-857188511f70,
  abstract     = {Ultrafast time-resolved fluorescence spectroscopy has been used to investigate the excited-state dynamics of the basic eumelanin building block 5,6-dihydroxyindole-2-carboxylic acid (DHICA), its acetylated, methylated, and carboxylic ester derivatives, and two oligomers, a dimer and a trimer in the O-acetylated forms. The results show that (1) excited-state decays are faster for the trimer relative to the monomer; (2) for parent DHICA, excited-state lifetimes are much shorter in aqueous acidic medium (380 ps) as compared to organic solvent (acetonitrile, 2.6 ns); and (3) variation of fluorescence spectra and excited-state dynamics can be understood as a result of excited-state intramolecular proton transfer (ESIPT). The dependence on the DHICA oligomer size of the excited-state deactivation and its ESIPT mechanism provides important insight into the photostability and the photoprotective function of eumelanin. Mechanistic analogies with the corresponding processes in DNA and other biomolecules are recognized.},
  author       = {Gauden, Magdalena and Pezzella, A and Panzella, L and Neves-Petersen, M and Skovsen, E and Petersen, S and Mullen, K and Napolitano, A and d'Ischia, M and Sundström, Villy},
  issn         = {1520-5126},
  language     = {eng},
  number       = {50},
  pages        = {17038--17043},
  publisher    = {The American Chemical Society},
  series       = {Journal of the American Chemical Society},
  title        = {Role of Solvent, pH, and Molecular Size in Excited-State Deactivation of Key Eumelanin Building Blocks: Implications for Melanin Pigment Photostability.},
  url          = {http://dx.doi.org/10.1021/ja806345q},
  volume       = {130},
  year         = {2008},
}