Tetrapyrrole Singlet Excited State Quenching by Carotenoids in an Artificial Photosynthetic Antenna
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- 作者：Rodrigo E. Palacios ; Gerdenis Kodis ; Christian Herrero ; Ernesto Mariñ ; o Ochoa ; Miguel Gervaldo ; Stephanie L. Gould ; John T. M. Kennis ; Devens Gust ; Thomas A. Moore ; Ana L. Moore
- 刊名：Journal of Physical Chemistry B
- 出版年：2006
- 出版时间：December 21, 2006
- 年：2006
- 卷：110
- 期：50
- 页码：25411 - 25420
- 全文大小：394K
- 年卷期：v.110,no.50(December 21, 2006)
- ISSN：1520-5207
文摘
Two artificial photosynthetic antenna models consisting of a Si phthalocyanine (Pc) bearing two axially attachedcarotenoid moieties having either 9 or 10 conjugated double bonds are used to illustrate some of the functionof carotenoids in photosynthetic membranes. Both models studied in toluene, methyltetrahydrofuran, andbenzonitrile exhibited charge separated states of the type C
+-Pc- confirming that the quenching of the PcS1 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 semiclassicalanalysis of the data in hexane at temperatures ranging from 180 to 320 K was used to demonstrate thatphotoinduced electron transfer could occur. The model bearing the 10 double bond carotenoids exhibitsbiexponential fluorescence decay in toluene and in hexane, which is interpreted in terms of an equilibriummixture of two isomers comprising s-cis and s-trans conformers of the carotenoid. The shorter fluorescencelifetime is associated with an s-cis carotenoid conformer where the close approach between the donor andacceptor moieties provides through-space electronic coupling in addition to the through-bond component.
+-Pc- confirming that the quenching of the PcS1 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 semiclassicalanalysis of the data in hexane at temperatures ranging from 180 to 320 K was used to demonstrate thatphotoinduced electron transfer could occur. The model bearing the 10 double bond carotenoids exhibitsbiexponential fluorescence decay in toluene and in hexane, which is interpreted in terms of an equilibriummixture of two isomers comprising s-cis and s-trans conformers of the carotenoid. The shorter fluorescencelifetime is associated with an s-cis carotenoid conformer where the close approach between the donor andacceptor moieties provides through-space electronic coupling in addition to the through-bond component.