Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Photochemistry of Pheomelanin Building Blocks and Model Chromophores: Excited-State Intra- and Intermolecular Proton Transfer

El Nahhas, Amal LU ; Pascher, Torbjörn LU ; Leone, Loredana ; Panzella, Lucia ; Napolitano, Alessandra and Sundström, Villy LU (2014) In The Journal of Physical Chemistry Letters 5(12). p.2094-2100
Abstract
Pheomelanins, the epidermal pigments of red-haired people responsible for their enhanced UV susceptibility, contain 1,4-benzothiazines and 1,3-benzothiazole as main structural components. Despite the major role played in pheomelanin phototoxicity, the photoreactivity of these species has so far remained unexplored. Static and time-resolved fluorescence spectroscopy was used to identify excited-state reactions of the two main pheomelanin benzothiazole building blocks, namely, the 6-(2-amino-2-carboxyethyl)-4-hydroxy-1,3-benzothiazole (BT) and the 2-carboxy derivative (BTCA) together with model chromophores lacking some of the ionizable functions. The results show that in aqueous buffer solution the OH at 4-position and the benzothiazole... (More)
Pheomelanins, the epidermal pigments of red-haired people responsible for their enhanced UV susceptibility, contain 1,4-benzothiazines and 1,3-benzothiazole as main structural components. Despite the major role played in pheomelanin phototoxicity, the photoreactivity of these species has so far remained unexplored. Static and time-resolved fluorescence spectroscopy was used to identify excited-state reactions of the two main pheomelanin benzothiazole building blocks, namely, the 6-(2-amino-2-carboxyethyl)-4-hydroxy-1,3-benzothiazole (BT) and the 2-carboxy derivative (BTCA) together with model chromophores lacking some of the ionizable functions. The results show that in aqueous buffer solution the OH at 4-position and the benzothiazole nitrogen atom control the photochemistry of both BT and BTCA via excited-state proton transfer to solvent (ESPT) and excited-state intramolecular proton transfer (ESIPT), while the amino acidic groups of the alanyl chain have a minor influence on the photochemistry. The ESPT and ESIPT produce several different excited-state ionic species with lifetimes ranging from similar to 100 ps to similar to 3 ns. (Less)
Please use this url to cite or link to this publication:
author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Letters
volume
5
issue
12
pages
2094 - 2100
publisher
The American Chemical Society (ACS)
external identifiers
  • wos:000337870100008
  • scopus:84903144136
  • pmid:26270498
ISSN
1948-7185
DOI
10.1021/jz500720g
language
English
LU publication?
yes
additional info
The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Chemical Physics (S) (011001060)
id
bc48f669-3ff4-4758-b947-a618616db091 (old id 4609137)
date added to LUP
2016-04-01 14:37:57
date last changed
2022-03-14 06:59:33
@article{bc48f669-3ff4-4758-b947-a618616db091,
  abstract     = {{Pheomelanins, the epidermal pigments of red-haired people responsible for their enhanced UV susceptibility, contain 1,4-benzothiazines and 1,3-benzothiazole as main structural components. Despite the major role played in pheomelanin phototoxicity, the photoreactivity of these species has so far remained unexplored. Static and time-resolved fluorescence spectroscopy was used to identify excited-state reactions of the two main pheomelanin benzothiazole building blocks, namely, the 6-(2-amino-2-carboxyethyl)-4-hydroxy-1,3-benzothiazole (BT) and the 2-carboxy derivative (BTCA) together with model chromophores lacking some of the ionizable functions. The results show that in aqueous buffer solution the OH at 4-position and the benzothiazole nitrogen atom control the photochemistry of both BT and BTCA via excited-state proton transfer to solvent (ESPT) and excited-state intramolecular proton transfer (ESIPT), while the amino acidic groups of the alanyl chain have a minor influence on the photochemistry. The ESPT and ESIPT produce several different excited-state ionic species with lifetimes ranging from similar to 100 ps to similar to 3 ns.}},
  author       = {{El Nahhas, Amal and Pascher, Torbjörn and Leone, Loredana and Panzella, Lucia and Napolitano, Alessandra and Sundström, Villy}},
  issn         = {{1948-7185}},
  language     = {{eng}},
  number       = {{12}},
  pages        = {{2094--2100}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{The Journal of Physical Chemistry Letters}},
  title        = {{Photochemistry of Pheomelanin Building Blocks and Model Chromophores: Excited-State Intra- and Intermolecular Proton Transfer}},
  url          = {{http://dx.doi.org/10.1021/jz500720g}},
  doi          = {{10.1021/jz500720g}},
  volume       = {{5}},
  year         = {{2014}},
}