PMID- 19007162
OWN - NLM
STAT- MEDLINE
DCOM- 20090206
LR  - 20081222
IS  - 1520-5126 (Electronic)
IS  - 0002-7863 (Linking)
VI  - 130
IP  - 50
DP  - 2008 Dec 17
TI  - Role of solvent, pH, and molecular size in excited-state deactivation of key 
      eumelanin building blocks: implications for melanin pigment photostability.
PG  - 17038-43
LID - 10.1021/ja806345q [doi]
AB  - 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.
FAU - Gauden, M
AU  - Gauden M
AD  - Department of Chemical Physics, Lund University, Box 124, S 22100 Lund, Sweden. 
      Magdalena.Gauden@chemphys.lu.se
FAU - Pezzella, A
AU  - Pezzella A
FAU - Panzella, L
AU  - Panzella L
FAU - Neves-Petersen, M T
AU  - Neves-Petersen MT
FAU - Skovsen, E
AU  - Skovsen E
FAU - Petersen, S B
AU  - Petersen SB
FAU - Mullen, K M
AU  - Mullen KM
FAU - Napolitano, A
AU  - Napolitano A
FAU - d'Ischia, M
AU  - d'Ischia M
FAU - Sundstrom, V
AU  - Sundstrom V
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Am Chem Soc
JT  - Journal of the American Chemical Society
JID - 7503056
RN  - 0 (Fluorescent Dyes)
RN  - 0 (Ions)
RN  - 0 (Melanins)
RN  - 0 (Solvents)
RN  - 12627-86-0 (eumelanin)
SB  - IM
MH  - Fluorescent Dyes/chemistry
MH  - Hydrogen-Ion Concentration
MH  - Ions/chemistry
MH  - Kinetics
MH  - Melanins/*chemistry
MH  - Molecular Structure
MH  - Molecular Weight
MH  - Photochemistry
MH  - Solvents/*chemistry
MH  - Spectrophotometry
MH  - Time Factors
EDAT- 2008/11/15 09:00
MHDA- 2009/02/07 09:00
CRDT- 2008/11/15 09:00
PHST- 2008/11/15 09:00 [pubmed]
PHST- 2009/02/07 09:00 [medline]
PHST- 2008/11/15 09:00 [entrez]
AID - 10.1021/ja806345q [doi]
PST - ppublish
SO  - J Am Chem Soc. 2008 Dec 17;130(50):17038-43. doi: 10.1021/ja806345q.