Long‐Lived Charge‐Separated State Generated in a Ferrocene–<i>meso</i>,<i>meso</i>‐Linked Porphyrin Trimer–Fullerene Pentad with a High Quantum Yield

Imahori, Hiroshi; Sekiguchi, Yuji; Kashiwagi, Yukiyasu; Sato, Tohru; Araki, Yasuyuki; Ito, Osamu; Yamada, Hiroko; Fukuzumi, Shunichi

doi:10.1002/chem.200305308

Cited by 209 publications

(139 citation statements)

References 80 publications

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“…copper complex catalyst | donor-acceptor dyad | nanosized silica-alumina | p-xylene | photoinduced electron transfer E xtensive efforts have been devoted to develop a variety of electron donor-acceptor linked molecules, which mimic charge-separation processes in the photosynthetic reaction center (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11); however, long-lived charge separation has been attained only in frozen media at low temperature (12)(13)(14)(15)(16)(17)(18) because intermolecular back electron transfer in solution is predominant as compared to the corresponding intramolecular process. For example, photoexcitation of a charge-shift type donor-acceptor dyad, 9-mesityl-10-methylacridinium ion (Acr þ -Mes) affords the electron-transfer (ET) state (Acr • -Mes •þ ) with an extremely long lifetime (e.g., 2 h at 203 K) in frozen media (18,19).…”

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Formation of a long-lived electron-transfer state in mesoporous silica-alumina composites enhances photocatalytic oxygenation reactivity

Fukuzumi

Doi

Itoh

et al. 2012

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

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119

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A simple donor-acceptor linked dyad, 9-mesityl-10-methylacridinium ion (Acr þ -Mes) was incorporated into nanosized mesoporous silica-alumina to form a composite, which in acetonitrile is highly dispersed. In this medium, upon visible light irradiation, the formation of an extremely long-lived electron-transfer state (Acr • -Mes •þ ) was confirmed by EPR and laser flash photolysis spectroscopic methods. The composite of Acr þ -Mes-incorporated mesoporous silica-alumina with an added copper complex [ðtmpaÞCu II ]ðClO 4 − Þ 2 (tmpa ¼ trisð2-pyridylmethylÞamine) acts as an efficient and robust photocatalyst for the selective oxygenation of p-xylene by molecular oxygen to produce p-tolualdehyde and hydrogen peroxide. Thus, incorporation of Acr þ -Mes into nanosized mesoporous silica-alumina combined with an O 2 -reduction catalyst (½ðtmpaÞCu II 2þ ) provides a promising method in the development of efficient and robust organic photocatalysts for substrate oxygenation by dioxygen, the ultimate environmentally benign oxidant.copper complex catalyst | donor-acceptor dyad | nanosized silica-alumina | p-xylene | photoinduced electron transfer

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confidence: 99%

Formation of a long-lived electron-transfer state in mesoporous silica-alumina composites enhances photocatalytic oxygenation reactivity

Fukuzumi

Doi

Itoh

et al. 2012

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

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119

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“…The LUMO of C 60 is triply degenerate to be able to accept up to 6 electrons to produce C 60 6-. [27][28][29] The 6-6 bond lengths in C 60…”

Section: As Electron Donor and Acceptor Componentsmentioning

confidence: 99%

Nanocarbons as Electron Donors and Acceptors in Photoinduced Electron-Transfer Reactions

Fukuzumi

2017

ECS J. Solid State Sci. Technol.

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Nanocarbons composed of hybridized sp2 carbons such as fullerenes, carbon nanotubes (CNTs), carbon nanohorns (CNHs) and graphene have been successfully utilized as electron acceptors in electron donor-acceptor hybrids for photoinduced electron-transfer reactions to mimic well the function of the photosynthetic reaction center. However, sp2 hybridized nanocarbons can also be used as electron donors when higher fullerenes such as C76 and C78 or endohedral metallofullerenes are employed or when nanocarbons are combined with relatively strong electron acceptors. This paper focuses on photoinduced electron-transfer reactions of nanocarbons including fullerenes, CNTs, CNHs and graphene, which act as not only as electron acceptors but also as electron donors with strong electron acceptors such as tetracyanoethylene (TCNE) and tetracyano-p-quinodimethan (TCNQ) to produce the radical cations efficiently because of small reorganization energies of electron transfer. Alternatively the oxidizing ability of electron acceptors was enhanced by binding Lewis acids to the radical anions, which enabled to oxidize nanocarbons. The important roles of nanocarbons such as fullerenes, carbon nanotubes and graphenes on the stability of rapidly emerging perovskite based solar cells with high power conversion efficiency have also been discussed in this paper.

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“…32 The lifetime of the final CS state (0.53 s at 163 K) has been attained without lowering the CS efficiency (È ¼ 0:83).…”

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confidence: 96%

Bioinspired Electron-Transfer Systems and Applications

Fukuzumi¹

2006

Bulletin of the Chemical Society of Japan

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199

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Bioinspired electron-transfer systems including artificial photosynthesis and respiration are presented herein together with some of their applications. First, multi-step electron-transfer systems composed of electron donor-acceptor ensembles have been developed, mimicking functions of the photosynthetic reaction center. However, a significant amount of energy is lost during the multi-step electron-transfer processes. Then, as an alternative to conventional charge-separation functional molecular models based on multi-step long-range electron transfer within redox cascades, simple donor-acceptor dyads have been developed to attain a long-lived and high energy charge-separated state without significant loss of excitation energy, by fine control of the redox potentials and of the geometry of donor-acceptor dyads that have small reorganization energies of electron transfer. Such simple molecular dyads, capable of fast charge separation but extremely slow charge recombination, have significant advantages with regard to synthetic feasibility, providing a variety of applications including construction of organic solar cells and development of efficient photocatalytic systems for the solar energy conversion. An efficient four-electron reduction of dioxygen to water by oneelectron reductants such as ferrocene derivatives as well as by an NADH analog has also been achieved as a respiration model by using a cofacial dicobalt porphyrin that can form the -peroxo Co(III)-O 2 -Co(III) complex. The catalytic mechanism of the four-electron reduction of dioxygen has been clarified based on the detailed kinetic study and the detection of the intermediate.There has been considerable interest in the photosynthetic reaction center of purple bacteria ever since the three-dimensional X-ray crystal structures of reaction centers of Rhodobacter (Rb.) sphaeroides 1 and other purple bacteria including Rhodopseudomonas (Rh.) viridis 2 have been disclosed. The photoinduced electron-transfer processes occur in a membrane-bound protein, which contains a number of cofactors, including four bacteriochlorophylls (BChl). Of these, the central part in Fig. 1 is referred to as the special pair [(BChl) 2 ], while the other two bacteriochlorophylls (BChl) are referred to as ''accessory'' bacteriochlorophylls. There are also two bacteriopheophytins (BPhe), two ubiquinones (Q A and Q B ), and a nonheme iron atom (not shown in Fig. 1), which together with the special pair are organized in pseudo-C 2 symmetry forming two branches (A and B). Light-initiated charge separation occurs between the special pair [(BChl) 2 ] and the neighboring pigments, leading to a radical cation [(BChl) 2 þ ]. Despite the quasi-symmetrical arrangement of the cofactors, the electrons are transported unidirectionally along the A-branch of the reaction center, 4-6 which suggests that the symmetry-breaking specific interactions with the protein are fundamentally important. The electron-transfer process is found to occur very rapidly from the special pair toward the quinones to pro...

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Long‐Lived Charge‐Separated State Generated in a Ferrocene–meso,meso‐Linked Porphyrin Trimer–Fullerene Pentad with a High Quantum Yield

Cited by 209 publications

References 80 publications

Formation of a long-lived electron-transfer state in mesoporous silica-alumina composites enhances photocatalytic oxygenation reactivity

Formation of a long-lived electron-transfer state in mesoporous silica-alumina composites enhances photocatalytic oxygenation reactivity

Nanocarbons as Electron Donors and Acceptors in Photoinduced Electron-Transfer Reactions

Bioinspired Electron-Transfer Systems and Applications

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