Rapid energy transfer in a dendrimer having π-conjugated light-harvesting antennas

Akai, Ichiro; Miyanari, K.; Shimamoto, Tadashi; Fujii, Atsuhiro; Nakao, Hiroyuki; Okada, Akira; Kanemoto, Katsuichi; Karasawa, T.; Hashimoto, Hideki; Ishida, Akihiro; Yamada, Akira; Katayama, Ikufumi; Takeda, Jun; Kimura, Mutsumi

doi:10.1088/1367-2630/10/12/125024

Cited by 10 publications

(14 citation statements)

References 36 publications

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“…In our recent studies [1], we found that a highly efficient ET takes place rapidly prior to achieving quasiequilibrium in the photoexcited state of the antenna in a star-shaped stilbenoid phthalocyanine dendrimer (SSS1Pc) [2], and also clarified that the ET quantum efficiency β ET improves at temperatures higher than ∼ 100 K. From this result, it was demonstrated that the rapid ET occurs at higher temperatures through the π-conjugated network mediated by the thermally activated torsional vibration of the LH-antenna subunit [3].…”

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confidence: 68%

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Vibration analyses and rapid energy transfer in π‐conjugated dendrimers having oligo phenylenevinylene antennas

Shimamoto

Miyanari

Fujii

et al. 2010

Phys. Status Solidi (c)

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From analyses of molecular vibrations, we have studied rapid energy transfer (ET) process in a series of star‐shaped stilbenoid phthalocyanines (SSSnPc;n=1,2) having π‐conjugated light harvesting antennas. In SSSnPc, the highly efficient ET occurs through a π‐conjugation network between the core and the antenna. However, a different temperature dependency of the ET efficiencies were found between SSS1Pc and SSS2Pc. In this report, molecular structures and torsional vibrations of the antenna subunits were analyzed in model molecules for SSSnPc. Consequently, it was found that the co‐planarities between the core and the antenna sub‐unit are different between SSS1Pc and SSS2Pc, and the variance in the temperature dependence of the ET efficiency in these dendrimers is originated from such difference of the co‐planarity (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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confidence: 68%

“…In optical measurements, these molecules were diluted in anhydrous tetrahydrofuran (THF) to concentrations in the range 10 −5 ∼ 10 −6 M. Sealed quartz tubes filled with the sample solution were prepared for measurements of the temperature dependence. More details of the experimental setup were described in [3]. PM6 Hamiltonian [5].…”

Section: Methodsmentioning

confidence: 99%

Vibration analyses and rapid energy transfer in π‐conjugated dendrimers having oligo phenylenevinylene antennas

Shimamoto

Miyanari

Fujii

et al. 2010

Phys. Status Solidi (c)

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“…Recently, we found that ET occurs rapidly prior to achieving quasi-equilibrium in the photoexcited state of the LH antenna in a star-shaped stilbenoid phthalocyanine dendrimer [4]. In addition, it was also clarified that the ET quantum efficiency improves at temperatures higher than ∼ 100 K. These results imply that highly efficient ET occurs at higher temperatures through the π-conjugated network mediated by the thermally activated torsional vibration of the LH-antenna subunit.…”

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confidence: 86%

“…In a π-conjugated LH dendrimer, we have reported that the quantum efficiency of the rapid ET increases with heating from 4 K to ∼ 200 K [4] and the thermally activated torsional vibration of the antenna subunit mediates the highly efficient rapid ET at room temperature (RT).…”

Section: Temperature Dependencementioning

confidence: 99%

Rapid energy transfer process through π‐conjugation network in meta* ‐linked branching dendrimers

Akai

Miyanari

Shimamoto

et al. 2010

Phys. Status Solidi (c)

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We investigated rapid energy transfer (ET) processes in dendrimers having meta ‐linked branching light harvesting antennas. It was found that, at room temperature (RT), the rapid ET occurs efficiently from the antennas to the core and gives rise to intense core‐PL bands under the selective excitation on the antenna. However, the ET efficiency impairs at lower temperatures than ∼100 K. For understanding these experimental results, we analyzed molecular vibrations and molecular orbitals (MOs) of a simple model molecule. From these analyses, it was demonstrated that, at RT, the torsional vibration of the entire antenna subunit is excited sufficiently and the torsional vibration improves the co‐planarity between the core and the antenna subunit, consequently, the rapid ET is realized by the short‐range interaction between the π*‐MOs of the core and the antenna. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…In such LH dendrimers, we found that the ET quantum efficiency exhibits obvious temperature dependence and improves at higher temperatures than 100 K. [2] In addition, we also demonstrated that low frequency vibrational modes such as torsional vibrations of the aromatic rings in the peripheral LH antenna subunit are sufficiently activated at such higher temperatures and the thermally excited torsional vibrations improve co-planarities between the neighbor aromatic rings in the LH antenna subunit and between the core and LH antenna subunits dynamically. [3] Such improvement of the co-planarities guarantees the highly efficient ET at higher temperatures than 100 K. [3] Probing of coherent phonon (CP) signals after pumping by femto-second laser pulses [4] is very useful to identify such low frequency vibrational modes because they have longer vibrational periods than the time duration (∼ 100 fs) of the pumping pulses. In this study, we focused on a typical LH antenna component molecule: 1, 3, 5-tri-phenylbenzene (tri-ph), in which three peripheral aromatic rings connect with the central rings at meta-positions.…”

Section: Introductionmentioning

confidence: 99%

Coherent Phonons in a 1,3,5-Tri-Phenylbenzene Crystal

Kawamoto¹,

Yoshizaki²,

Yamashiro³

et al. 2014

Proceedings of the 12th Asia Pacific Physics Conference (APPC12)

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We studied low frequency vibrational modes in a light-harvesting (LH) antenna component molecule (1, 3, 5-tri-phenylbenzene: tri-ph) of a LH dendrimer by measuring a coherent phonon (CP) signal and molecular vibration analyses with semi-empirical molecular orbital calculations. In a Fourier transform spectrum obtained from the transient CP signal, we found three vibrating components with the frequencies of 35 ± 13, 60 ± 10, and 84 ± 14 cm −1 . In the lower frequency range than 100 cm −1 , the molecular vibration analyses give the following three kinds of vibrational modes: torsional vibrations, a butterfly vibration and bending vibrations, in which peripheral aromatic rings librate against the central ring in different manners. We identified the lowest frequency vibrating component (35 ± 13 cm −1 ) as the torsional vibrational mode changing dihedral angles and co-planarities between the central and the peripheral aromatic rings. In addition, it was also found that the vibrational frequencies obtained by our measurements are higher than those of the vibrational mode analyses. These hardenings are considered to account for steric hindrance between the neighbor molecules after the crystallization.

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Rapid energy transfer in a dendrimer having π-conjugated light-harvesting antennas

Cited by 10 publications

References 36 publications

Vibration analyses and rapid energy transfer in π‐conjugated dendrimers having oligo phenylenevinylene antennas

Vibration analyses and rapid energy transfer in π‐conjugated dendrimers having oligo phenylenevinylene antennas

Rapid energy transfer process through π‐conjugation network in meta* ‐linked branching dendrimers

Coherent Phonons in a 1,3,5-Tri-Phenylbenzene Crystal

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Rapid energy transfer in a dendrimer having π-conjugated light-harvesting antennas

Cited by 10 publications

References 36 publications

Vibration analyses and rapid energy transfer in π‐conjugated dendrimers having oligo phenylenevinylene antennas

Vibration analyses and rapid energy transfer in π‐conjugated dendrimers having oligo phenylenevinylene antennas

Rapid energy transfer process through π*‐conjugation network in meta ‐linked branching dendrimers

Coherent Phonons in a 1,3,5-Tri-Phenylbenzene Crystal

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Rapid energy transfer process through π‐conjugation network in meta* ‐linked branching dendrimers