A Molecular Tetrad Allowing Efficient Energy Storage for 1.6 s at 163 K

Guldi, Dirk M.; Imahori, Hiroshi; Tamaki, Koichi; Kashiwagi, Yukiyasu; Yamada, Hiroko; Sakata, Yoshiteru; Fukuzumi, Shunichi

doi:10.1021/jp036382n

Cited by 170 publications

(97 citation statements)

References 54 publications

(52 reference statements)

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“…[17][18][19][20][21][22][23][24][25] Not surprising, ultrafast charge separation together with very slow charge recombination lead in fullerene based electron donor-acceptor systems to unprecedentedly long-lived radical ion pair states with high quantum efficiencies -vide infra. 4,[26][27][28] Next to influences stemming from reorganization energies, the intervening medium between electron donors and acceptors governs the electronic coupling and, thus, the electron transfer dynamics. In particular, the top region of the Marcus parabola is modulated by the magnitude of electronic coupling V. In principle, the electronic coupling depends on the involved states of electron donors and acceptors and their respective distances (R DA ).…”

Section: Etmentioning

confidence: 99%

A multicomponent molecular approach to artificial photosynthesis – the role of fullerenes and endohedral metallofullerenes

2016

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In this review article, we highlight recent advances in the field of solar energy conversion at a molecular level.We focus mainly on investigations regarding fullerenes as well as endohedral metallofullerenes in energy and/ or electron donor-acceptor conjugates, hybrids, and arrays, but will also discuss several more advanced systems. Hereby, the mimicry of the fundamental processes occurring in natural photosynthesis, namely light harvesting (LH), energy transfer (EnT), reductive/oxidative electron transfer (ET), and catalysis (CAT), which serve as a blue print for the rational design of artificial photosynthetic systems, stand at the focalpoint. Importantly, the key processes in photosynthesis, that is, LH, EnT, ET, and CAT, define the structure of this review with the only further differentiation in terms of covalent and non-covalent systems. Fullerenes as well as endohedral metallofullerenes are chosen by virtue of their small reorganization energies in electron transfer processes, on the one hand, and their exceptional redox behaviour, on the other hand.

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Section: Etmentioning

confidence: 99%

A multicomponent molecular approach to artificial photosynthesis – the role of fullerenes and endohedral metallofullerenes

2016

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“…70 Further improvement of the longest lifetime of a final charge-separated state (1.6 s in DMF at 164 K) together with a total CS efficiency (34%) was recorded for Fc-ZnP-ZnP-C 60 tetrad, in which the H 2 P moiety of 11 was replaced by ZnP. 90 Although the lifetimes of the final charge-separated states 70,90 are comparable to those of bacteriochlorophyll dimer radical cation ((Bchl) 2 þ )-secondary quinone radical anion (Q B À ) ion pair in bacteria photosynthetic reaction centers, 20,21 the maximal CS efficiency (34%) is still lower than the natural value (%100%) in bacteria photosynthetic reaction centers. To improve a quantum yield for the formation of a final charge-separated state, we focused on meso,meso-linked porphyrins 18 as an excellent electron carrier as well as a light-harvesting antenna.…”

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confidence: 94%

Creation of Fullerene-Based Artificial Photosynthetic Systems

Imahori¹

2007

Bulletin of the Chemical Society of Japan

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154

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Various porphyrin-fullerene-linked systems have been prepared to elucidate the intrinsic electron-transfer properties of fullerenes. Photodynamical studies on porphyrin-fullerene-linked systems showed that spherical fullerenes accelerated photoinduced electron transfer and charge-shift, but slowed down charge recombination, which is in sharp contrast with those of conventional planar acceptors such as quinones and imides. For the first time, it was shown that the unique electron-transfer properties result from the small reorganization energies of fullerenes arising from the delocalized system on the sphere together with the rigid structure. The small reorganization energies make it possible to produce a long-lived charge-separated state with a high quantum yield in donor-fullerene systems. The finding also will allow us to construct light energy conversion systems as well as artificial photosynthetic models. Highly efficient photoinduced energy and electron transfer were achieved on gold and ITO electrodes modified with self-assembled monolayers of the porphyrin-fullerene-linked systems. We also developed dye-sensitized bulk heterojunction solar cell possessing both characteristics of dye-sensitized and bulk heterojunction solar cells. These results showed the advantages of fullerenes as electron acceptors in artificial photosynthetic model, photonic molecular devices and machines, and organic molecular electronics including solar cells.

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“…The motivation to use OPE is threefold: (1) OPEs are known for their molecular wire properties, [42][43][44] and thus longer-lived CSS due to a better spatial separation of the charges could be expected; (2) the distance between two adjacent NDIs amounts to about 7-8 Å and is thus more favorable than POP for zippertype assembly via π stacking; 17,18 (3) the OPE scaffold absorbs around 400 nm and can also take part in light harvesting.…”

Section: Introductionmentioning

confidence: 99%

Excited-State Dynamics of Hybrid Multichromophoric Systems: Toward an Excitation Wavelength Control of the Charge Separation Pathways

et al. 2009

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The photophysical properties of two hybrid multichromophoric systems consisting of an oligophenylethynyl (OPE) scaffold decorated by 10 red or blue naphthalene diimides (NDIs) have been investigated using femtosecond spectroscopy. Ultrafast charge separation was observed with both red and blue systems. However, the nature of the charge-separated state and its lifetime were found to differ substantially. For the red system, electron transfer occurs from the OPE scaffold to an NDI unit, independently of whether the OPE or an NDI is initially excited. However, charge separation upon OPE excitation is about 10 times faster, and takes place with a 100 fs time constant. The average lifetime of the ensuing charge-separated state amounts to about 650 ps. Charge separation in the blue system depends on which of the OPE scaffold or an NDI is excited. In the first case, an electron is transferred from the OPE to an NDI and the hole subsequently shifts to another NDI unit, whereas in the second case symmetry-breaking charge separation between two NDI units occurs. Although the charges are located on two NDIs in both cases, different recombination dynamics are observed. This is explained by the location of the ionic NDI moieties that depends on the charge separation pathway, hence on the excitation wavelength. The very different dynamics observed with red and blue systems can be accounted for by the oxidation potentials of the respective NDIs that are higher and lower than that of the OPE scaffold. Because of this, the relative energies of the two charge-separated states (hole on the OPE or an NDI) are inverted.

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A Molecular Tetrad Allowing Efficient Energy Storage for 1.6 s at 163 K

Cited by 170 publications

References 54 publications

A multicomponent molecular approach to artificial photosynthesis – the role of fullerenes and endohedral metallofullerenes

A multicomponent molecular approach to artificial photosynthesis – the role of fullerenes and endohedral metallofullerenes

Creation of Fullerene-Based Artificial Photosynthetic Systems

Excited-State Dynamics of Hybrid Multichromophoric Systems: Toward an Excitation Wavelength Control of the Charge Separation Pathways

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