O2(a1Δg) production and quenching by C60 and C70

Black, G.; Dunkle, E. A.; Dorko, Ernest A.; Schlie, L. A.

doi:10.1016/1010-6030(93)85034-6

Cited by 18 publications

(16 citation statements)

References 28 publications

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“…It is very clear from Figure 2 that the O 2 (a 1 Δ) phosphorescence spectrum in C 60 -CCl 4 solutions appears symmetric with its peak position at 1273 nm, in good agreement with the previous report in literature. 24 However, it is surprising that the PL spectrum from C 60 -H 2 O ultrasonic suspensions exhibits an asymmetric structure with its peak position at 1283 nm, which is evidently different from the above spectrum observed in C 60 organic solutions, and also from the symmetric spectrum centered at 1283 nm observed in C 60 aqueous suspensions by Bilski et al. 21 Interestingly, the similar asymmetric spectra were also found in some other nC 60 suspensions, such as C 60 -C 2 H 5 OH/D 2 O ultrasonic suspensions and aqueous stir-nC 60 suspensions, as well as in solid C 60 powder (see Figure S4).…”

Section: Methodsmentioning

confidence: 99%

Long-Lifetime and Asymmetric Singlet Oxygen Photoluminescence from Aqueous Fullerene Suspensions

et al. 2013

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The photoexcited aqueous fullerene (C 60 ) suspension was shown to exhibit an asymmetric photoluminescence (PL) spectrum, which, different from the symmetric spectrum observed previously in C 60 solutions or suspensions, still stems from the characteristic phosphorescence of singlet oxygen (O 2 (a 1 Δ)) owing to its dependence on oxygen concentration. In contrast to the microsecond-level lifetime of O 2 (a 1 Δ) in water solutions, that in our C 60 suspensions was measured at room temperature to be relatively long, about 2−3 ms, which is ∼1000 times longer than the value reported by Bilski et al. The physical mechanism for the asymmetric O 2 (a 1 Δ) PL from C 60 suspensions was studied in depth, indicating that it in fact originates from O 2 molecules trapped in the C 60 lattice within the suspended C 60 aggregates (nC 60 ). This mechanism, which can explain well our above results, was further validated by the nC 60 's high-resolution transmission electron microscopy (HRTEM) images with lattice fringes and the experimental temperature dependence of O 2 (a 1 Δ) lifetimes in nC 60 suspensions. Our findings suggest that the bulk-phase O 2 (a 1 Δ) in aqueous nC 60 suspensions results from the diffusion of the O 2 (a 1 Δ) generated within the interior of nC 60 aggregates.

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Section: Methodsmentioning

confidence: 99%

Long-Lifetime and Asymmetric Singlet Oxygen Photoluminescence from Aqueous Fullerene Suspensions

et al. 2013

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“…To the best of our knowledge, this is the first report of the fluorescence quenching of a water-soluble C 60 derivative, since previous quenching studies focused on the triplet excited state. [1][2][3][4][5][6][7]11 We now center on the elucidation of the quenching mechanism. In the case of bromobenzene and cyclohexyl iodide in ethanol and toluene, the quenching mechanism is likely to be the external heavyatom effect, as has been observed for C 70 and derivatives in halogenated solvents.…”

Section: Mechanism Of Fluorescence Quenchingmentioning

confidence: 99%

“…Intermolecular quenching of the triplet excited state of fullerenes by charge and electron [1][2][3][4] and energy [5][6][7] transfer has been extensively investigated in recent years. Quenching of the singlet excited state has received less attention, [8][9][10] in part owing to the very low fluorescence quantum yield of fullerenes.…”

Section: Introductionmentioning

confidence: 99%

Photophysics and Photochemistry of a Water-Soluble C₆₀ Dendrimer: Fluorescence Quenching by Halides and Photoinduced Oxidation of I^-

et al. 2001

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Using electronic absorption spectroscopy, and steady-state and time-resolved fluorescence, we studied the singlet state properties of dendro [60]fullerene, a C 60 methanoderivative whose addend is a water-soluble dendrimer. Fluorescence quenching, especially by halide ions in water, was characterized at several temperatures. From a new relation for the activation energy of a diffusion-influenced reaction and from a comparison with the quenching in organic solvents, it is concluded that the quenching occurs by the external heavy-atom effect. An efficient photoinduced oxidation of iodide in aerated solutions and in the presence of a fullerene is also reported. The photoinduced oxidation mechanism exclusively involves ground-state oxygen.

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“…5 CS 2 was selected as solvent based on the relatively long lifetime of 1 O 2 (τ ) 79 ms) 6 and high solubility of C 60 in CS 2 (7.9 mg/ mL). 7 The 1 O 2 quenching was monitored by its characteristic phosphorescence at 1270 nm.…”

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confidence: 99%

Can H₂ Inside C₆₀ Communicate with the Outside World?

et al. 2007

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The recent synthesis 1 of H 2 @C 60 and D 2 @C 60 has provided photochemists with an opportunity to investigate whether the simplest molecule, H 2 , incarcerated inside a fullerene, can communicate with the electronically excited walls of its fullerene container and with excited molecules in the "outside world". 2 We report investigations comparing the photophysical characteristics of triplet C 60 and triplet H 2 @C 60 and the quenching of singlet molecular oxygen, 1 O 2 by C 60 , H 2 @C 60 , and D 2 @C 60 . For comparison, the quenching of 1 O 2 by H 2 and D 2 in solution is reported for the first time. Although the interactions of hydrogen with the walls of triplet C 60 were found to be too weak to be determined by either triplet-triplet absorption or EPR spectroscopy, we report a significant interaction between singlet molecular oxygen ( 1 O The interaction of incarcerated H 2 and D 2 with the walls of triplet fullerene was examined by laser flash photolysis, employing pulses from a Nd:YAG laser (532 nm, ∼5 ns pulse width). C 60 shows a triplet-triplet absorption centered at 747 nm, which was utilized to determine the triplet lifetimes of C 60 , H 2 @C 60 , and D 2 @C 60 in benzene solutions. No differences in the triplet lifetimes were observed within our experimental error (τ ) 110 ( 8 µs; for further details see Supporting Information). Thus, the interaction of incarcerated H 2 and D 2 with the paramagnetic walls of the triplet fullerene is too weak to be determined by triplet lifetime measurements.The magnitude of the interaction of incarcerated H 2 and D 2 with the triplet fullerene was also examined by time-resolved EPR (TREPR). TREPR spectra and transient decay kinetics of C 60 , H 2 @C 60 , and D 2 @C 60 were studied in benzene, toluene, and methylcyclohexane at 285 K. No differences in the spectra and transient decay kinetics of 3 C 60 , H 2 @ 3 C 60 , and D 2 @ 3 C 60 were found.Although there was no measurable interaction of incarcerated H 2 or D 2 with the triplet walls of C 60 , we searched for an interaction with the incarcerated H 2 and D 2 with an external electronically excited molecule, singlet molecular oxygen, 1 O 2 .Large differences in the quenching of 1 O 2 by H-X and D-X bonds are well-known. 3 To the best of our knowledge, there are no reports of the rate constants for quenching of 1 O 2 by H 2 or D 2 in solution, although a large isotope effect is found in the gas phase. 4 It was therefore of interest to determine the quenching rate constants of 1 O 2 by H 2 and D 2 in solution and to compare these rate constants with those for H 2 @C 60 and D 2 @C 60 in solution.The absolute quenching rate constants of 1 O 2 by H 2 @C 60 and D 2 @C 60 were determined using a time-resolved method, employing the host, C 60 , which is known to be an efficient 1 O 2 sensitizer. 5 CS 2 was selected as solvent based on the relatively long lifetime of 1 O 2 (τ ) 79 ms) 6 and high solubility of C 60 in CS 2 (7.9 mg/ mL). 7 The 1 O 2 quenching was monitored by its characteristic phosphorescence at 1270 nm. ...

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O2(a1Δg) production and quenching by C60 and C70

Cited by 18 publications

References 28 publications

Long-Lifetime and Asymmetric Singlet Oxygen Photoluminescence from Aqueous Fullerene Suspensions

Long-Lifetime and Asymmetric Singlet Oxygen Photoluminescence from Aqueous Fullerene Suspensions

Photophysics and Photochemistry of a Water-Soluble C₆₀ Dendrimer: Fluorescence Quenching by Halides and Photoinduced Oxidation of I^-

Can H₂ Inside C₆₀ Communicate with the Outside World?

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O2(a1Δg) production and quenching by C60 and C70

Cited by 18 publications

References 28 publications

Long-Lifetime and Asymmetric Singlet Oxygen Photoluminescence from Aqueous Fullerene Suspensions

Long-Lifetime and Asymmetric Singlet Oxygen Photoluminescence from Aqueous Fullerene Suspensions

Photophysics and Photochemistry of a Water-Soluble C60 Dendrimer: Fluorescence Quenching by Halides and Photoinduced Oxidation of I-

Can H2 Inside C60 Communicate with the Outside World?

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Photophysics and Photochemistry of a Water-Soluble C₆₀ Dendrimer: Fluorescence Quenching by Halides and Photoinduced Oxidation of I^-

Can H₂ Inside C₆₀ Communicate with the Outside World?