Photochemistry of Pheomelanin Building Blocks and Model Chromophores: Excited-State Intra- and Intermolecular Proton Transfer
(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:
https://lup.lub.lu.se/record/4609137
- author
- El Nahhas, Amal LU ; Pascher, Torbjörn LU ; Leone, Loredana ; Panzella, Lucia ; Napolitano, Alessandra and Sundström, Villy LU
- organization
- publishing date
- 2014
- 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}}, }