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Title: Photoinduced Electron and Energy Transfer in a Molecular Triad Featuring a Fullerene Redox Mediator

Authors:
; ; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Bio-Inspired Solar Fuel Production (BISfuel)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1369662
DOE Contract Number:
SC0001016
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry; Journal Volume: 120; Journal Issue: 27; Related Information: BISfuel partners with Arizona State University.
Country of Publication:
United States
Language:
English

Citation Formats

Antoniuk-Pablant, Antaeres, Kodis, Gerdenis, Moore, Ana L., Moore, Thomas A., and Gust, Devens. Photoinduced Electron and Energy Transfer in a Molecular Triad Featuring a Fullerene Redox Mediator. United States: N. p., 2016. Web. doi:10.1021/acs.jpcb.6b03470.
Antoniuk-Pablant, Antaeres, Kodis, Gerdenis, Moore, Ana L., Moore, Thomas A., & Gust, Devens. Photoinduced Electron and Energy Transfer in a Molecular Triad Featuring a Fullerene Redox Mediator. United States. doi:10.1021/acs.jpcb.6b03470.
Antoniuk-Pablant, Antaeres, Kodis, Gerdenis, Moore, Ana L., Moore, Thomas A., and Gust, Devens. 2016. "Photoinduced Electron and Energy Transfer in a Molecular Triad Featuring a Fullerene Redox Mediator". United States. doi:10.1021/acs.jpcb.6b03470.
@article{osti_1369662,
title = {Photoinduced Electron and Energy Transfer in a Molecular Triad Featuring a Fullerene Redox Mediator},
author = {Antoniuk-Pablant, Antaeres and Kodis, Gerdenis and Moore, Ana L. and Moore, Thomas A. and Gust, Devens},
abstractNote = {},
doi = {10.1021/acs.jpcb.6b03470},
journal = {Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry},
number = 27,
volume = 120,
place = {United States},
year = 2016,
month = 7
}
  • Excitation of carotenoid-porphyrin-quinone (C-P-Q) triads yields the porphyrin first excited singlet state, which decays by electron transfer to give a C-P[sup [center dot]+]-Q[sup [center dot]-] charge-separated state. Competing with rapid charge recombination is electron transfer from the carotenoid to produce a long-lived C[sup [center dot]+]-P-Q[sup [center dot]-] species. High quantum yields of the final state require tuning of electronic and thermodynamic factors to favor forward electron transfer over charge recombination. Triad 1 illustrates a new strategy for slowing charge recombination based on coupling photoinduced electron transfer to a change in proton chemical potential. The quantum yields and lifetimes of themore » final charge-separated states in the triads were assessed by monitoring the transient carotenoid radical cation absorptions. The results demonstrate that the yield of charge separation in multicomponent molecular photovoltaics can be increased by a coordinated electron and proton transfer process. It is also interesting that in 1 a substantial fraction of the intramolecular redox potential produced by photoinduced electron transfer is transformed into proton chemical potential. Elaboration of this concept could lead to photoinduced generation of proton motive force in a heterogeneous system. 24 refs., 3 figs.« less
  • Time-resolved fluorescence and absorption techniques have been used to investigate energy and photoinduced electron transfer in a covalently linked free-base porphyrin-fullerene dyad and its zinc analogue. In toluene, the porphyrin first excited singlet states decay in about 20 ps by singlet-singlet energy transfer to the fullerene. The fullerene first excited singlet state is not quenched and undergoes intersystem crossing to the triplet, which exists in equilibrium with the porphyrin triplet state. In benzonitrile, photoinduced electron transfer from the porphyrin first excited singlet state to the fullerene competes with energy transfer. The fullerene excited singlet state is also quenched by electronmore » transfer from the porphyrin. Overall, the charge-separated state is produced with a quantum yield approaching unity. This state lives for 290 ps in the free-base dyad and 50 ps in the zinc analog. These long lifetimes suggest that such dyads may be useful as components of more complex light-harvesting systems. 32 refs., 12 figs., 1 tab.« less
  • We report ultrafast transient absorption studies of photoinduced electron transfer in the triad molecule zinc methyl 13{sup 1}-desoxopyropheophorbide a-pyromellitimide-1,8:4, 5-naphthalenediimide (ZC-PI-NI) in solution. The absorption spectra of the radical anions of PI and NI possess narrow and well-separated absorption bands which permit the direct observation of both the intermediate and final charge-separated states. Selective optical excitation of the ZC donor results in the formation of the intermediate charge-separated state, ZC{sup +}-PI{sup -}-NI, in less than 2 ps in nonpolar solvents. The PI radical ion within the ZC{sup +}-PI{sup -}-NI intermediate is vibrationally excited as illustrated by time-dependent changes in themore » band shape of its transient absorption spectrum. The rate of the initial charge separation reaction forming ZC{sup +}-PI{sup -}-NI and the subsequent charge shift reaction to form the final state, ZC{sup +}-PI-NI{sup -}, as well as the appearance of the vibrationally excited intermediate are all highly solvent dependent even for solvents with similar dielectric constants. Analogous dyad control molecules ZCPI and ZCNI were also studied and compared with the results for ZCPINI. 41 refs., 8 figs., 3 tabs.« less
  • Charge separation of photogenerated ion pairs was achieved in nearly quantitative yields by employing zinc tetrakis(N-methylpyridinium)porphyrin as a sensitizer, zwitterionic (sulfonatopropyl)viologen as an electron mediator, and a bilayer membrane of amphipathic viologen as an electron pool. The quantum yield of viologen ion radicals, in the presence of triethanolamine as a sacrificial electron donor, remained high (0.80 +/- 0.02) over a wide range of amphipathic viologen concentration (20 ..mu..M-5mM). This value coincided with the quantum yield of initially generated viologen ion radicals as estimated from laser flash photolysis of the sensitizer-electron mediator binary system. The high quantum yield was attributed tomore » the rapid and very efficient harvesting of the electron-carrying mediator and the successive electron transfer to the surface of the viologen bilayer membrane, which enables temporary storage of the captured electron. Relevance of the present system to chemical conversion and storage of solar energy is discussed. 30 references, 8 figures.« less
  • A molecular triad consisting of a diarylporphyrin (P) covalently linked to a carotenoid polyene (C) and a fullerene (C{sub 60}) has been prepared and studied using time-resolved spectroscopic methods. In 2-methyltetrahydrofuran solution, the triad undergoes photoinduced electron transfer to yield C-P{sup .+}-C{sub 60}{sup .-}, which evolves into C{sup .+}-P-C{sub 60}{sup .-} with an overall quantum yield of 0.14. This state decays by charge recombination to yield the carotenoid triplet state with a time constant of 170 ns. Even in a glass at 77 K, C{sup .+}-P-C{sub 60}{sup .-} is formed with a quantum yield of nearly 0.10 and again decaysmore » mainly by charge recombination to give {sup 3}C-P-C{sub 60}. The fullerene triplet, formed through normal intersystem crossing, is also observed at 77K. the generation in the triad of a long-lived charge separated state by photoinduced electron transfer, the low-temperature electron transfer behavior, and the formation of a triplet state by charge recombination are phenomena previously observed mostly in photosynthetic reaction centers. 36 refs., 5 figs.« less