Photodriven charge separation in a carotenoporphyrin–quinone triad

Moore, Thomas A.; Gust, Devens; Mathis, Paul; Mialocq, J.C.; Chachaty, C.; Bensasson, René V.; Land, Edward J.; Doizi, D.; Liddell, Paul A.; Lehman, William R.; Nemeth, Gregory A.; Moore, Ana L.

doi:10.1038/307630a0

Cited by 285 publications

(106 citation statements)

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“…11−15 Most reports utilized a nanometers-thick lipid bilayer membrane containing molecular dyes, which initiated the proton pumping process by a photoinduced proton-coupled electron-transfer reaction. [4][5][6]8,9 The report by Bakker and colleagues was unique, because it used a 30 μm thick microporous polyethylene membrane impregnated with merocyanine photoacid dye molecules to sensitize the light-to-ionic energy conversion process. 15 The authors observed a ∼210 mV photovoltage using bidirectional excitation from a Xe arc lamp.…”

Section: ■ Introductionmentioning

confidence: 99%

Observation of Photovoltaic Action from Photoacid-Modified Nafion Due to Light-Driven Ion Transport

et al. 2017

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Replacing passive ion-exchange membranes, like Nafion, with membranes that use light to drive ion transport would allow membranes in photoelectrochemical technologies to serve in an active role. Toward this, we modified perfluorosulfonic acid ionomer membranes with organic pyrenol-based photoacid dyes to sensitize the membranes to visible light and initiate proton transport. Covalent modification of the membranes was achieved by reacting Nafion sulfonyl fluoride poly-(perfluorosulfonyl fluoride) membranes with the photoacid 8-hydroxypyrene-1,3,6-tris(2-aminoethylsulfonamide). The modified membranes were strongly colored and maintained a high selectivity for cations over anions. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and ionexchange measurements together provided strong evidence of covalent bond formation between the photoacids and the polymer membranes. Visible-light illumination of the photoacid-modified membranes resulted in a maximum power-producing ionic photoresponse of ∼100 μA/cm 2 and ∼1 mV under 40 Suns equivalent excitation with 405 nm light. In comparison, membranes that did not contain photoacids and instead contained ionically associated Ru II −polypyridyl coordination compound dyes, which are not photoacids, exhibited little-to-no photoeffects (∼1 μA/cm 2 ). These disparate photocurrents, yet similar yields for nonradiative excited-state decay from the photoacids and the Ru II dyes, suggest temperature gradients were not likely the cause of the observed photovoltaic action from photoacid-modified membranes. Moreover, spectral response measurements supported that light absorption by the covalently bound photoacids was required in order to observe photoeffects. These results represent the first demonstration of photovoltaic action from an ion-exchange membrane and offer promise for supplementing the power demands of electrochemical processes with renewable sunlight-driven ion transport.

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Section: ■ Introductionmentioning

confidence: 99%

Observation of Photovoltaic Action from Photoacid-Modified Nafion Due to Light-Driven Ion Transport

et al. 2017

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“…T o construct nanoscale devices or molecular wires that efficiently convert photon energies to chemical potentials, extensive studies have produced photoinduced, long-distance charge separation (CS) states by using donor (D)-acceptor (A)-linked multiarray systems that mimic natural photosynthesis (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11). In each intramolecular, sequential electron transfer (ET) step, an electron or a hole tunnels between D and A over substantial distances (Ͼ10 Å) as in the natural photosynthetic reaction centers (12).…”

mentioning

confidence: 99%

Primary charge-recombination in an artificial photosynthetic reaction center

Kobori

Yamauchi

Akiyama

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

101

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Photoinduced primary charge-separation and charge-recombination are characterized by a combination of time-resolved optical and EPR measurements of a fullerene-porphyrin-linked triad that undergoes fast, stepwise charge-separation processes. The electronic coupling for the energy-wasting charge recombination is evaluated from the singlet-triplet electronic energy gap in the short-lived, primary charge-separated state. The electronic coupling is found to be smaller by Ϸ40% than that for the primary charge-separation. This inhibition of the electronic interaction for the charge-recombination to excited triplet state largely results from a symmetry-broken electronic structure modulated by configuration interaction between 3 (b1u,b3g) and 3 (au, b3g) electronic states of the free-base porphyrin.electronic coupling ͉ long-range electron transfer ͉ molecular orbital symmetry T o construct nanoscale devices or molecular wires that efficiently convert photon energies to chemical potentials, extensive studies have produced photoinduced, long-distance charge separation (CS) states by using donor (D)-acceptor (A)-linked multiarray systems that mimic natural photosynthesis (1-11). In each intramolecular, sequential electron transfer (ET) step, an electron or a hole tunnels between D and A over substantial distances (Ͼ10 Å) as in the natural photosynthetic reaction centers (12). From Marcus theory (13)(14)(15)(16)(17)(18)(19)(20), the ET rate constant (k ET ) is described (in the weak coupling regime) aswhere -h is Planck's constant divided by 2 and V, the electronic coupling matrix element, represents the electronic tunneling interaction between D and A. FCWDS denotes Franck-Condon weighted density of states parameterized by the reorganization energy ( ) and the driving force (Ϫ⌬G) for the ET reaction. The FCWDS term is given by (4where k B is the Boltzmann constant and T is the temperature. Although for several long-range ET systems, V has been interpreted in terms of a superexchange coupling model (21) that bridges the redox sites (22-28), much remains to be resolved regarding the tunneling mechanism (29-34). In addition, characterizations of V will be useful for designing molecular electronic devices (35). Key to efficient photoinduced CS is prevention of the energywasting charge recombination (CR) characterized in part by V. Although V and have been investigated for various ET steps by experimentally measuring k ET s in systems such as D 2 -D 1 -A triad (7, 9, 36) and protein complexes (24,25,34), primary CR,-A has escaped elucidation, especially in the efficient stepwise CS systems because the CR kinetics is hidden by subsequent CS processes,In the photosynthetic reaction center protein of Rhodobacter sphaeroides, which contains as cofactors a special pair (P), two bacteriopheopheophytins (H A and H B ), and two quinones (Q A and Q B ), the CR kinetics of the primary CS state of P ؉• H A Ϫ• Q A cannot easily be observed, because H A Ϫ• 3 Q A forward ET (Ϸ200 ps) is much faster than the primary CR (10-20 ns, which has b...

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“…The synthesis of a molecule that mimics the reaction centre in natural photosynthesis was reported in 1984 by 12 scientists from three countries [11]. The molecule consists of three parts in a 'triad'.…”

Section: Light-driven Charge Separation In a Carotenoporphyrin-quinonmentioning

confidence: 99%

Photosynthesis: From Natural Towards Artificial

Chow

2003

Journal of Biological Physics

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Abstract. Photosynthesis, the natural process that yields food, fuel and fibre, spans physical and biological sciences, spatially from atomic scales to the global and temporally from electronic transitions to the evolutionary time frame. Photosynthesis is highly efficient in its primary energy capture, but much less so in terms of conversion to crop yield. The natural photosynthetic system provides fertile ground for exploring and dissecting partial processes that may be mimicked in artificial systems for human needs, perhaps with improved efficiency. Future developments are limited only by the imagination.

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Photodriven charge separation in a carotenoporphyrin–quinone triad

Cited by 285 publications

References 28 publications

Observation of Photovoltaic Action from Photoacid-Modified Nafion Due to Light-Driven Ion Transport

Observation of Photovoltaic Action from Photoacid-Modified Nafion Due to Light-Driven Ion Transport

Primary charge-recombination in an artificial photosynthetic reaction center

Photosynthesis: From Natural Towards Artificial

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