Photophysics of Open C<sub>60</sub> Derivatives

Stackow, Robert; Schick, Georg; Jarrosson, Thibaut; Rubin, and Yves; Foote, Christopher S.

doi:10.1021/jp001358k

Cited by 18 publications

(13 citation statements)

References 24 publications

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“…The Φ T values of substituted fullerenes are lower than 134, 35 and are reported to be 0.8 for methanofullerenes 21, 34. Importantly, the values of Φ Δ and Φ T are found to be identical for C 60 and its closed‐cage26 or open‐cage36 derivatives as well as for higher fullerenes such as C 70 37 and C 76 38. Therefore, the measure of Φ Δ can be taken as an indirect evaluation of Φ T for all fullerenes 39…”

Section: Resultsmentioning

confidence: 88%

Photophysical Properties of the ReI and RuII Complexes of a New C60-Substituted Bipyridine Ligand

et al. 2002

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The rhenium(I) and ruthenium(II) complexes of a fullerene‐substituted bipyridine ligand have been prepared. Electrochemical studies indicate that some ground state electronic interaction between the fullerene subunit and the metal‐complexed moiety are present in the ReI but not the RuII complex. The photophysical properties have been investigated by steady‐state and time‐resolved UV/Vis‐NIR luminescence spectroscopy and nanosecond laser flash photolysis in CH2Cl2 solution, and compared to those of the corresponding model compounds. Excitation of the methanofullerene moiety in the dyads does not lead to excited state intercomponent interactions. Instead, excitation of the metal‐complexed unit shows that the lowest triplet metal‐to‐ligand‐charge‐transfer excited state (3MLCT) centered on the ReI‐ or RuII‐type unit is quenched with a rate constant of about 2.5×108 s−1. The quenching is attributed to an electron‐transfer (ElT) process leading to the reduction of the carbon sphere, as determined by luminescence spectroscopy for the RuII dyad. Experimental detection of electron transfer in the ReI dyad is prevented due to the unfavorable absorption of the metal‐complexed moiety relative to the fullerene unit. However, it can be postulated on the basis of energetic/kinetic arguments and by comparison with the RuII‐type array. The primary ElT process is followed by charge‐recombination to give the lowest‐lying fullerene triplet excited state (3C60) with quantitative yield, as determined by sensitized singlet oxygen luminescence experiments. Direct 3MLCT→3C60 triplet–triplet energy‐transfer (EnT) does not successfully compete with ElT since it is highly exoergonic and located in the Marcus inverted region. The quantum yield of singlet oxygen sensitization (ΦΔ) of the ReI‐based dyad is found to be lower (0.80) than for the corresponding RuII derivative (1.0). This is likely to be the consequence of different conformational structures for the two dyads, rather than a different yield of 3C60 formation.

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Section: Resultsmentioning

confidence: 88%

Photophysical Properties of the ReI and RuII Complexes of a New C60-Substituted Bipyridine Ligand

et al. 2002

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“…[45] The quantum yield of singlet oxygen sensitization (F D ) and of fullerene triplet formation (F T ) are found to be identical for C 60 , for its closed-cage [46] and open-cage [47] derivatives, as well as for higher fullerenes like C 70 [48] and C 76 . The excited 1 O 2 * state deactivates to the ground state, giving rise to a characteristic IR emission band centered at l = 1268 nm.…”

Section: Triplet Behaviormentioning

confidence: 98%

“…The excited 1 O 2 * state deactivates to the ground state, giving rise to a characteristic IR emission band centered at l = 1268 nm. [45] The quantum yield of singlet oxygen sensitization (F D ) and of fullerene triplet formation (F T ) are found to be identical for C 60 , for its closed-cage [46] and open-cage [47] derivatives, as well as for higher fullerenes like C 70 [48] and C 76 . [49] Therefore, the value of F D , which is proportional to the intensity of the sensitized IR emission of 1 O 2 *, [42,50] can be used as an indirect measurement of F T for all fullerenes.…”

Section: Triplet Behaviormentioning

confidence: 99%

Structure‐Dependent Photoinduced Electron Transfer in Fullerodendrimers with Light‐Harvesting Oligophenylenevinylene Terminals

Armaroli

Accorsi

Clifford

et al. 2006

Chemistry An Asian Journal

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Oligophenylenevinylene (OPV)-terminated phenylenevinylene dendrons G1-G4 with one, two, four, and eight "side-arms", respectively, were prepared and attached to C60 by a 1,3-dipolar cycloaddition of azomethine ylides generated in situ from dendritic aldehydes and N-methylglycine. The relative electronic absorption of the OPV moiety increases progressively along the fullerodendrimer family C60G1-C60G4, reaching a 99:1 ratio for C60G4 (antenna effect). UV/Vis and near-IR luminescence and transient absorption spectroscopy was used to elucidate photoinduced energy and electron transfer in C60G1-C60G4 as a function of OPV moiety size and solvent polarity (toluene, dichloromethane, benzonitrile), taking into account the fact that the free-energy change for electron transfer is the same along the series owing to the invariability of the donor-acceptor couple. Regardless of solvent, all the fullerodendrimers exhibit ultrafast OPV-->C60 singlet energy transfer. In CH2Cl2, the OPV-->C60 electron transfer from the lowest fullerene singlet level ((1)C60*) is slightly exergonic (deltaG(CS) approximately = 0.07 eV), but is observed, to an increasing extent, only in the largest systems C60G2-C60G4 with lower activation barriers for electron transfer. This effect has been related to a decrease of the reorganization energy upon enlargement of the molecular architecture. Structural factors are also at the origin of an unprecedented OPV-->C60 electron transfer observed for C60G3 and C60G4 in apolar toluene, whereas in benzonitrile, electron transfer occurs in all cases. Monitoring of the lowest fullerene triplet state by sensitized singlet oxygen luminescence and transient absorption spectroscopy shows that this level is populated through intersystem crossing and is not involved in photoinduced electron transfer.

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“…Previous reports have shown that small perturbations in the π system give similar photophysical properties as those of pristine fullerene, but a larger number of substitutions result in more significant changes. [18][19][20][21][22][23][24][25][26][27][28][29] In light of the large number of applications for these novel compounds, there has been widespread effort to elucidate the relationship between the structure of these derivatives and their photophysical properties. [30][31][32][33][34] Pratt et al have reported a homologous series of methanofullerenes showing that the number of perturbations of the π system at different sites within the fullerene framework cause systematic changes in the triplet state properties.…”

Section: Introductionmentioning

confidence: 99%

Photophysical Properties of a 1,2,3,4,5,6-Hexasubstituted Fullerene Derivative

et al. 2006

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The photophysical properties of a novel 1,2,3,4,5,6-hexasusbstituted fullerene derivative (1) are examined in this study. In addition to the ground state absorption spectrum of 1 we report its triplettriplet absorption spectrum and molar extinction coefficient (Δε T-T ), as well as the triplet quantum yield (Φ T ), lifetime (τ T ), and energy (E T ). The saturation of a single six-member ring on the fullerene cage results in significant changes in the triplet state properties as compared to that of pristine C 60 . The triplet-triplet absorption spectrum shows a hypsochromic shift in long wavelength absorption and both the triplet state lifetime and triplet quantum yield are decreased. The triplet energy was found to be similar to that of C 60 . In addition, the quantum yield (Φ Δ ) of singlet oxygen generated by 1 was calculated and is found to be significantly less than in the case of C 60 .

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Photophysics of Open C₆₀ Derivatives

Cited by 18 publications

References 24 publications

Photophysical Properties of the ReI and RuII Complexes of a New C60-Substituted Bipyridine Ligand

Photophysical Properties of the ReI and RuII Complexes of a New C60-Substituted Bipyridine Ligand

Structure‐Dependent Photoinduced Electron Transfer in Fullerodendrimers with Light‐Harvesting Oligophenylenevinylene Terminals

Photophysical Properties of a 1,2,3,4,5,6-Hexasubstituted Fullerene Derivative

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Photophysics of Open C60 Derivatives

Cited by 18 publications

References 24 publications

Photophysical Properties of the ReI and RuII Complexes of a New C60-Substituted Bipyridine Ligand

Photophysical Properties of the ReI and RuII Complexes of a New C60-Substituted Bipyridine Ligand

Structure‐Dependent Photoinduced Electron Transfer in Fullerodendrimers with Light‐Harvesting Oligophenylenevinylene Terminals

Photophysical Properties of a 1,2,3,4,5,6-Hexasubstituted Fullerene Derivative

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Photophysics of Open C₆₀ Derivatives