Tetrapyrrole singlet excited state quenching by carotenoids in an artificial phótosynthetic antenna

Rodrigo E. Palacios, Gerdenis Kodis, Christian Herrero, Ernesto Mariño Ochoa, Miguel Gervaldo, Stephanie L. Gould, John T M Kennis, Devens Gust, Thomas Moore, Ana Moore

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Two artificial photosynthetic antenna models consisting of a Si phthalocyanine (Pc) bearing two axially attached carotenoid moieties having either 9 or 10 conjugated double bonds are used to illustrate some of the function of carotenoids in photosynthetic membranes. Both models studied in toluene, methyltetrahydrofuran, and benzonitrile exhibited charge separated states of the type C.+-Pc.- confirming that the quenching of the Pc S1 state is due to photoinduced electron transfer. In hexane, the Pc S1 state of the 10 double bond carotenoid-Pc model was slightly quenched but the C.+-Pc.- transient was not spectroscopically detected. A semiclassical analysis of the data in hexane at temperatures ranging from 180 to 320 K was used to demonstrate that photoinduced electron transfer could occur. The model bearing the 10 double bond carotenoids exhibits biexponential fluorescence decay in toluene and in hexane, which is interpreted in terms of an equilibrium mixture of two isomers comprising s-cis and s-trans conformers of the carotenoid. The shorter fluorescence lifetime is associated with an s-cis carotenoid conformer where the close approach between the donor and acceptor moieties provides through-space electronic coupling in addition to the through-bond component.

Original languageEnglish (US)
Pages (from-to)25411-25420
Number of pages10
JournalJournal of Physical Chemistry B
Volume110
Issue number50
DOIs
StatePublished - Dec 21 2006

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Tetrapyrroles
carotenoids
Carotenoids
Excited states
Quenching
antennas
quenching
Antennas
Hexanes
Bearings (structural)
Hexane
excitation
Toluene
toluene
Photosynthetic membranes
electron transfer
Fluorescence
fluorescence
Electrons
Isomers

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Tetrapyrrole singlet excited state quenching by carotenoids in an artificial phótosynthetic antenna. / Palacios, Rodrigo E.; Kodis, Gerdenis; Herrero, Christian; Ochoa, Ernesto Mariño; Gervaldo, Miguel; Gould, Stephanie L.; Kennis, John T M; Gust, Devens; Moore, Thomas; Moore, Ana.

In: Journal of Physical Chemistry B, Vol. 110, No. 50, 21.12.2006, p. 25411-25420.

Research output: Contribution to journalArticle

Palacios, Rodrigo E. ; Kodis, Gerdenis ; Herrero, Christian ; Ochoa, Ernesto Mariño ; Gervaldo, Miguel ; Gould, Stephanie L. ; Kennis, John T M ; Gust, Devens ; Moore, Thomas ; Moore, Ana. / Tetrapyrrole singlet excited state quenching by carotenoids in an artificial phótosynthetic antenna. In: Journal of Physical Chemistry B. 2006 ; Vol. 110, No. 50. pp. 25411-25420.
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