Self-assembled aggregates of the carotenoid zeaxanthin: time-resolved study of excited states
(2005) In The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory 109(8). p.1521-1529- Abstract
- In this study, we present a way of controlling the formation of the two types of zeaxanthin aggregates in hydrated ethanol: J-zeaxanthin (head-to-tail aggregate, characteristic absorption band at 530 nm) and H-zeaxanthin (card-pack aggregate, characteristic absorption band at 400 run). To control whether J- or H-zeaxanthin is formed, three parameters are important: (1) pH, that is, the ability to form a hydrogen bond; (2) the initial concentration of zeaxanthin, that is, the distance between zeaxanthin molecules; and (3) the ratio of ethanol/water. To create H-aggregates, the ability to form hydrogen bonds is crucial, while J-aggregates are preferentially formed when hydrogen-bond formation is prevented. Further, the formation of... (More)
- In this study, we present a way of controlling the formation of the two types of zeaxanthin aggregates in hydrated ethanol: J-zeaxanthin (head-to-tail aggregate, characteristic absorption band at 530 nm) and H-zeaxanthin (card-pack aggregate, characteristic absorption band at 400 run). To control whether J- or H-zeaxanthin is formed, three parameters are important: (1) pH, that is, the ability to form a hydrogen bond; (2) the initial concentration of zeaxanthin, that is, the distance between zeaxanthin molecules; and (3) the ratio of ethanol/water. To create H-aggregates, the ability to form hydrogen bonds is crucial, while J-aggregates are preferentially formed when hydrogen-bond formation is prevented. Further, the formation of J-aggregates requires a high initial zeaxanthin concentration and a high ethanol/water ratio, while H-aggregates are formed under the opposite conditions. Time-resolved experiments revealed that excitation of the 530-nm band of J-zeaxanthin produces a different relaxation pattern than excitation at 485 and 400 run, showing that the 530-nm band is not a vibrational band of the S-2 state but a separate excited state formed by J-type aggregation. The excited-state dynamics of zeaxanthin aggregates are affected by annihilation that occurs in both J- and H-aggregates. In H-aggregates, the dominant annihilation component is on the subpicosecond time scale, while the main annihilation component for the J-a-gregate is 5 ps. The S-1 lifetimes of aggregates are longer than in solution, yielding 20 and 30 ps for H- and J-zeaxanthin, respectively. In addition, H-type aggregation promotes a new relaxation channel that forms the zeaxanthin triplet state. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/151977
- author
- Billsten, Helena LU ; Sundström, Villy LU and Polivka, Tomas LU
- organization
- publishing date
- 2005
- type
- Contribution to journal
- publication status
- published
- subject
- in
- The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
- volume
- 109
- issue
- 8
- pages
- 1521 - 1529
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- wos:000227247900005
- scopus:14844363437
- ISSN
- 1520-5215
- DOI
- 10.1021/jp044847j
- 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
- b57e4c11-e639-4388-aadc-b7c01a09e750 (old id 151977)
- date added to LUP
- 2016-04-01 16:18:39
- date last changed
- 2022-03-30 06:58:51
@article{b57e4c11-e639-4388-aadc-b7c01a09e750,
abstract = {{In this study, we present a way of controlling the formation of the two types of zeaxanthin aggregates in hydrated ethanol: J-zeaxanthin (head-to-tail aggregate, characteristic absorption band at 530 nm) and H-zeaxanthin (card-pack aggregate, characteristic absorption band at 400 run). To control whether J- or H-zeaxanthin is formed, three parameters are important: (1) pH, that is, the ability to form a hydrogen bond; (2) the initial concentration of zeaxanthin, that is, the distance between zeaxanthin molecules; and (3) the ratio of ethanol/water. To create H-aggregates, the ability to form hydrogen bonds is crucial, while J-aggregates are preferentially formed when hydrogen-bond formation is prevented. Further, the formation of J-aggregates requires a high initial zeaxanthin concentration and a high ethanol/water ratio, while H-aggregates are formed under the opposite conditions. Time-resolved experiments revealed that excitation of the 530-nm band of J-zeaxanthin produces a different relaxation pattern than excitation at 485 and 400 run, showing that the 530-nm band is not a vibrational band of the S-2 state but a separate excited state formed by J-type aggregation. The excited-state dynamics of zeaxanthin aggregates are affected by annihilation that occurs in both J- and H-aggregates. In H-aggregates, the dominant annihilation component is on the subpicosecond time scale, while the main annihilation component for the J-a-gregate is 5 ps. The S-1 lifetimes of aggregates are longer than in solution, yielding 20 and 30 ps for H- and J-zeaxanthin, respectively. In addition, H-type aggregation promotes a new relaxation channel that forms the zeaxanthin triplet state.}},
author = {{Billsten, Helena and Sundström, Villy and Polivka, Tomas}},
issn = {{1520-5215}},
language = {{eng}},
number = {{8}},
pages = {{1521--1529}},
publisher = {{The American Chemical Society (ACS)}},
series = {{The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory}},
title = {{Self-assembled aggregates of the carotenoid zeaxanthin: time-resolved study of excited states}},
url = {{http://dx.doi.org/10.1021/jp044847j}},
doi = {{10.1021/jp044847j}},
volume = {{109}},
year = {{2005}},
}