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• W2040337615 endingPage "3734" @default.
• W2040337615 startingPage "3727" @default.
• W2040337615 abstract "The structural factors underlying the peculiar optical properties and visible chromophore of eumelanin biopolymers are largely uncharted. It is known that synthetic eumelanins from 5,6-dihydroxyindole are black and display a featureless UV−visible absorption spectrum, whereas those from 5,6-dihydroxyindole-2-carboxylic acid (1) are lighter in color and exhibit a distinct band around 310 nm, but the origin of this difference has never been addressed in detail. Recently, we showed that 5,6-dihydroxyindole dimers generate on pulse radiolysis oxidation strongly absorbing transients with intense maxima in the 500−600 nm region, which have been attributed to planar extended quinone methide species. We now report the unexpectedly different behavior of three oligomers from 1, namely, the 4,4′-biindolyl 2, the 4,7′-biindolyl 3, and the 4,7′:4′,7′′-terindolyl 4. Pulse radiolysis oxidation of 2−4 led initially to semiquinone intermediates exhibiting similar absorption maxima at 360−380 nm. Semiquinone absorption decay followed second-order kinetics (2k = 1.4 × 108, 3.2 × 108, and 1.4 × 108 M−1 s−1 for 2, 3, and 4, respectively) but did not lead to significant chromophore development in the visible region. Similar absorption traces were obtained from monomer 1. DFT calculations predicted 5,6-dihydroxyindolyl-5,6-indolequinone structures with significant dihedral twists across the interunit single bonds for the most stable two-electron oxidation products of 2 and 3. The computed absorption spectra consistently featured strong bands around 310 nm but little or no absorption in the visible region. It is suggested that the effective conjugation length in oligomeric/polymeric eumelanin components from 1 may be controlled by hindered rotation around inter-ring bonds preventing planarization of the continuous array of indole units. This may provide an explanation for the difference in the absorption properties of polymers from the two key eumelanin monomers." @default.
• W2040337615 created "2016-06-24" @default.
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• W2040337615 date "2009-04-22" @default.
• W2040337615 modified "2023-10-18" @default.
• W2040337615 title "Lack of Visible Chromophore Development in the Pulse Radiolysis Oxidation of 5,6-Dihydroxyindole-2-carboxylic Acid Oligomers: DFT Investigation and Implications for Eumelanin Absorption Properties" @default.
• W2040337615 cites W1964490726 @default.
• W2040337615 cites W1967234505 @default.
• W2040337615 cites W1971731720 @default.
• W2040337615 cites W1972222358 @default.
• W2040337615 cites W1973171098 @default.
• W2040337615 cites W1985982307 @default.
• W2040337615 cites W1986787960 @default.
• W2040337615 cites W1987409772 @default.
• W2040337615 cites W1989327881 @default.
• W2040337615 cites W1990149232 @default.
• W2040337615 cites W1991437967 @default.
• W2040337615 cites W1991523967 @default.
• W2040337615 cites W1993742748 @default.
• W2040337615 cites W1995794402 @default.
• W2040337615 cites W1997151511 @default.
• W2040337615 cites W1999608519 @default.
• W2040337615 cites W2001727684 @default.
• W2040337615 cites W2004306557 @default.
• W2040337615 cites W2008423326 @default.
• W2040337615 cites W2009531950 @default.
• W2040337615 cites W2010816819 @default.
• W2040337615 cites W2016407422 @default.
• W2040337615 cites W2017472847 @default.
• W2040337615 cites W2020522570 @default.
• W2040337615 cites W2021502908 @default.
• W2040337615 cites W2025707010 @default.
• W2040337615 cites W2028273608 @default.
• W2040337615 cites W2030971064 @default.
• W2040337615 cites W2032341483 @default.
• W2040337615 cites W2032432859 @default.
• W2040337615 cites W2033990154 @default.
• W2040337615 cites W2035998662 @default.
• W2040337615 cites W2039169747 @default.
• W2040337615 cites W2041503571 @default.
• W2040337615 cites W2043017482 @default.
• W2040337615 cites W2046424037 @default.
• W2040337615 cites W2050299745 @default.
• W2040337615 cites W2050307366 @default.
• W2040337615 cites W2053539299 @default.
• W2040337615 cites W2054597947 @default.
• W2040337615 cites W2056046419 @default.
• W2040337615 cites W2057802887 @default.
• W2040337615 cites W2062055939 @default.
• W2040337615 cites W2062466402 @default.
• W2040337615 cites W2062894166 @default.
• W2040337615 cites W2063663126 @default.
• W2040337615 cites W2066594169 @default.
• W2040337615 cites W2068119928 @default.
• W2040337615 cites W2068228867 @default.
• W2040337615 cites W2069197437 @default.
• W2040337615 cites W2070709018 @default.
• W2040337615 cites W2074120588 @default.
• W2040337615 cites W2075306105 @default.
• W2040337615 cites W2078914111 @default.
• W2040337615 cites W2080584000 @default.
• W2040337615 cites W2082110869 @default.
• W2040337615 cites W2083509916 @default.
• W2040337615 cites W2085571306 @default.
• W2040337615 cites W2088456425 @default.
• W2040337615 cites W2089199196 @default.
• W2040337615 cites W2095474273 @default.
• W2040337615 cites W2108591023 @default.
• W2040337615 cites W2110110714 @default.
• W2040337615 cites W2118691572 @default.
• W2040337615 cites W2159882250 @default.
• W2040337615 cites W2160356714 @default.
• W2040337615 cites W2164563076 @default.
• W2040337615 cites W2165953552 @default.
• W2040337615 cites W2724780140 @default.
• W2040337615 cites W2949267072 @default.
• W2040337615 doi "https://doi.org/10.1021/jo900250v" @default.
• W2040337615 hasPubMedId "https://pubmed.ncbi.nlm.nih.gov/19385623" @default.
• W2040337615 hasPublicationYear "2009" @default.
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