Charge-transfer emission of compact porphyrin–fullerene dyad analyzed by Marcus theory of electron-transfer

Vehmanen, Visa; Tkachenko, Nikolai V.; Imahori, Hiroshi; Fukuzumi, Shunichi; Lemmetyinen, Helge

doi:10.1016/s1386-1425(01)00496-6

Cited by 143 publications

(134 citation statements)

References 49 publications

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“…The instrumentation and the data analysis procedure have been described earlier. [20,21] 2-(3-Hydroxypropoxy)benzaldehyde: Potassium hydroxide (3.8 g, 56.3 mmol, 85 % purity) was dissolved in EtOH (60 mL). The flask was attached to a reflux condenser with a rubber septum on top and purged with nitrogen.…”

Section: Methodsmentioning

confidence: 99%

Synthesis, Conformational Interconversion, and Photophysics of Tethered Porphyrin–Fullerene Dyads with Parachute Topology

Fazio

Durandin

Tkachenko

et al. 2009

Chemistry A European J

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The synthesis of a porphyrin-fullerene dyad with "parachute" topology is reported. To determine whether the dyad is "flexing" at room temperature, low-temperature NMR experiments were used. Computational modeling has shown the low-energy conformation of the dyad to be nonsymmetric. Although, (1)H NMR spectroscopy at room temperature is consistent with a molecule with C(2v) symmetry, the spectrum changes on lowering the temperature consistent with "windshield wiper"-like motion, in which the porphyrin moiety rotates from one side of the C(60) sphere to the other. Nanosecond and picosecond fluorescence lifetime experiments show two components contribute to the fluorescence decay, also consistent with the presence of more than one conformer.

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Section: Methodsmentioning

confidence: 99%

Synthesis, Conformational Interconversion, and Photophysics of Tethered Porphyrin–Fullerene Dyads with Parachute Topology

Fazio

Durandin

Tkachenko

et al. 2009

Chemistry A European J

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“…The parameters S and V denote the solvent reorganization energy and the intramolecular reorganization energy, respectively. From charge-transfer emission spectra of a porphyrin-C 60 dyad with the donor-acceptor in close proximity, V ϭ 0.05 eV (1 eV ϭ 1.602 ϫ 10 Ϫ19 J) and ϭ 0.14 eV were determined for the CR to the ground state (53). For the porphyrin-C 60 dyad systems in Fig.…”

Section: Analyses Of Electronic Coupling Matrix Elementsmentioning

confidence: 99%

Primary charge-recombination in an artificial photosynthetic reaction center

Kobori

Yamauchi

Akiyama

et al. 2005

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

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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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“…64,66,72,87,101 We determined various ET parameters, including V and , for porphyrin-fullerene systems from the CT absorption and emission for the first time. 64,66,72,87,101 Such CT absorption and emission were also reported for other fullerene-porphyrin-linked [102][103][104][105] and fullerene-phthalocyanine-linked 106 systems. Furthermore, the specific -interaction has been successfully used in dye-sensitized bulk heterojunction solar cells consisting of porphyrin and fullerene (vide infra).…”

Section: Introductionmentioning

confidence: 99%

“…Porphyrinfullerene-linked dyad 4 and the freebase porphyrin (H 2 P) analog are good candidates to minimize the value, because porphyrin and fullerene with small are fixed in a close proximity. 49,66,72 The values of ET parameters including , ÀÁG 0 ET , and V were determined by analyzing the CT absorption and emission in nonpolar solvents for the first time. ably.…”

Section: Introductionmentioning

confidence: 99%

Creation of Fullerene-Based Artificial Photosynthetic Systems

Imahori¹

2007

Bulletin of the Chemical Society of Japan

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156

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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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Charge-transfer emission of compact porphyrin–fullerene dyad analyzed by Marcus theory of electron-transfer

Cited by 143 publications

References 49 publications

Synthesis, Conformational Interconversion, and Photophysics of Tethered Porphyrin–Fullerene Dyads with Parachute Topology

Synthesis, Conformational Interconversion, and Photophysics of Tethered Porphyrin–Fullerene Dyads with Parachute Topology

Primary charge-recombination in an artificial photosynthetic reaction center

Creation of Fullerene-Based Artificial Photosynthetic Systems

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