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melanin_oligomers_photophysics_blancafort_chemrxiv.pdf (18.32 MB)

Computational Study of Absorption Spectra of Eumelanin Constituents: Key Role of Oxidized Species in the Red Edge Absorption

preprint
submitted on 13.03.2019, 02:11 and posted on 13.03.2019, 13:48 by Gerard Riesco, Aleix Casademont, Lluís Blancafort
We have computed the vertical absorption of the basic components of eumelanin, oligomers of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA), at the TD-DFT level. Here we present a preliminary report on the results for 73 DHI and 58 DHICA oligomers that cover the structural and redox diversity found in eumelanin. We have identified several structures that absorb at wave lengths above 800 nm, all of which contain oxidized DHI units, ie quinones or quinone methides. The transitions also have a pronounced charge transfer character, which suggests that they may give rise to proton-coupled electron transfer radiationless decay mechanisms that are important for the photoprotecting function.

Funding

Ministerio de Economía y Competitividad, Spain (CTQ2015-69363-P)

History

Email Address of Submitting Author

lluis.blancafort@udg.edu

Institution

Universitat de Girona

Country

Spain

ORCID For Submitting Author

0000-0002-0003-5540

Declaration of Conflict of Interest

No conflict of interest

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