Anion radicals of [60]-fullerene and its ortho-quinodimethane adducts generated by cathodic reduction and photochemical electron transfer: an EPR and vis—near-IR study

Staško, Andrej; Brezová, Vlasta; Biskupič, Stanislav; Dinse, Klaus−Peter; Groß, Ralf; Baumgarten, Martin; Gügel, Andreas; Belik, Pavel

doi:10.1016/s0022-0728(96)04693-1

Cited by 21 publications

(8 citation statements)

References 36 publications

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“…We notice that the charge absorption of C 60 in Figure C is very broad and featureless, which is in contrast with much sharper ion bands reported for fullerenes in literature. ,,, The spectral broadness can, on the one hand, be attributed to the overlap of the C 60 anion and cation bands, but it is also related to the delocalization of the charges in C 60 aggregates. To confirm this, we compare the spectral signature to the photoinduced anion band obtained when the C 60 film is blended with the prototypical small-molecule donor TAPC.…”

contrasting

confidence: 54%

Femtosecond Dynamics of Photoexcited C₆₀ Films

Causa

Ramírez

Hardigree

et al. 2018

J. Phys. Chem. Lett.

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The well known organic semiconductor C is attracting renewed attention due to its centimeter-long electron diffusion length and high performance of solar cells containing 95% fullerene, yet its photophysical properties remain poorly understood. We elucidate the dynamics of Frenkel and intermolecular (inter-C) charge-transfer (CT) excitons in neat and diluted C films from high-quality femtosecond transient absorption (TA) measurements performed at low fluences and free from oxygen or pump-induced photodimerization. We find from preferential excitation of either species that the CT excitons give rise to a strong electro-absorption (EA) signal but are extremely short-lived. The Frenkel exciton relaxation and triplet yield strongly depend on the C aggregation. Finally, TA measurements on full devices with applied electric field allow us to optically monitor the dissociation of CT excitons into free charges for the first time and to demonstrate the influence of cluster size on the spectral signature of the C anion.

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contrasting

confidence: 54%

Femtosecond Dynamics of Photoexcited C₆₀ Films

Causa

Ramírez

Hardigree

et al. 2018

J. Phys. Chem. Lett.

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“…Recently, the attention has been drawn also to the effects on the spin relaxation of the fullerene radical anions caused by the equilibria between different aggregates in solution . The tendency of fullerenes to give rise to aggregates is now well documented .…”

Section: Discussionmentioning

confidence: 99%

“…The high symmetry of the spin distribution can give rise to anomalously large line widths. , The fullerenes form easily aggregates, whose structure is not known. There are clear evidences that the multiple EPR signals detected can be attributed to different aggregates, whose nature and interconversion dynamics depend on solvent, concentration, and temperature . Moreover, the multistage reduction is very easy, and the spin multiplicity of some of the multireduction products is still discussed .…”

Section: Introductionmentioning

confidence: 99%

Radical Anions of Mono- and Bis-fulleropyrrolidines: An EPR Study

Brustolon¹,

Zoleo²,

Agostini³

et al. 1998

J. Phys. Chem. A

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The radical anions of three C60 derivatives (N-methyl-3,4-fulleropyrrolidine, N-methyl-2-(3,6,9-trioxadecyl)-3,4-fulleropyrrolidine, and bis-N-methyl-3,4-fulleropyrrolidine are respectively MFP-, tegMFP-, and bisMFP-) have been investigated by continuous wave (cw) and pulsed EPR in methyltetrahydrofuran and tetrahydrofuran solutions. The EPR spectra for MFP- and tegMFP- show a 1:1:1 triplet, due to the hyperfine coupling with the pyrrolidine nitrogen. The EPR spectrum of bisMFP- shows a superimposition of two signals, each due to a 1:2:3:2:1 quintet. Each quintet is due to the hyperfine coupling with the two pyrrolidine nitrogen atoms. The two signals are attributed to two different conformers of the radical. A direct transfer of spin density from the sphere to the nitrogen atoms is discussed as arising from the bent conformation of the pyrrolidine rings. All the spectra show several weaker satellite lines, due to the radical anions containing a 13C atom. From their analysis a C 2 v symmetry for the spin distribution is obtained in the case of MFP- and tegMFP-. The EPR line widths of these latter radicals at room temperature are larger than those expected on the basis of spin relaxation due to rotational diffusion in solution, and the line widths decrease upon decreasing the temperature. Pulsed EPR measurements of T 1 in liquid and frozen solutions show that the EPR line widths are determined by the anomalously short lifetimes of the spin states. The temperature dependence of T 1 obeys to the Arrhenius law, giving an activation energy of 7 kJ/mol. The latter results are compared with those obtained in the past for the lone . They are attributed to the closeness of the electronic levels, due to the weak perturbation of the pyrrolidine ring on the symmetrical electronic distribution of C60. On the other hand, the spin relaxation properties of bisMFP- are shown those expected for a nonsymmetrical radical. The comparison of cw- and pulsed-EPR spectra of MFP- in frozen solutions of MeTHF and THF indicates the presence of aggregates of interacting radicals in THF.

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“…367 Studies on fullerene derivatives of the type R 2 C 60 -are more appropriate models for the sharp signal in C 60 -. Signals ascribable to such species have been reported to have g values close to 2.000 and line widths of 1-2 G. 108,132,230,232,[368][369][370] In temperaturedependent studies on the well characterized anion of N-methyl [60]fulleropyrollidine, the g value was 2.0006 and the line width was 3 G at room temperature. It decreased to about 1 G at liquid helium temperatures with the onset of noticeable anisotropy.…”

Section: Origins Of Sharp Signalsmentioning

confidence: 99%

Discrete Fulleride Anions and Fullerenium Cations

2000

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His research interests include reactive cation and superacid chemistry with inert carborane counterions, ionic liquids, bioinorganic chemistry, spin-coupling phenomena, fullerene chemistry, and new carbon-or porphyrin-based materials. He is a Sloan Fellow, a Dreyfus Teacher−Scholar Awardee, and a Guggenheim Fellow. Robert Bolskar received his B.S. degree in Chemistry from Carroll College in Waukesha, WI, in 1992. He earned his Ph.D. degree at the University of Southern California in Los Angeles under the direction of Christopher Reed in 1997, investigating the synthetic redox chemistry of fullerene anions and cations. In 1998 he moved to the University of California, Riverside, as Managing Research Associate. He is currently Senior Chemist at TDA Research in Wheat Ridge, CO. His research interests include the chemistry and physics of fullerene compounds, supramolecular chemistry, strongly oxidizing systems, and electrophilic cations.

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Anion radicals of [60]-fullerene and its ortho-quinodimethane adducts generated by cathodic reduction and photochemical electron transfer: an EPR and vis—near-IR study

Cited by 21 publications

References 36 publications

Femtosecond Dynamics of Photoexcited C₆₀ Films

Femtosecond Dynamics of Photoexcited C₆₀ Films

Radical Anions of Mono- and Bis-fulleropyrrolidines: An EPR Study

Discrete Fulleride Anions and Fullerenium Cations

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Anion radicals of [60]-fullerene and its ortho-quinodimethane adducts generated by cathodic reduction and photochemical electron transfer: an EPR and vis—near-IR study

Cited by 21 publications

References 36 publications

Femtosecond Dynamics of Photoexcited C60 Films

Femtosecond Dynamics of Photoexcited C60 Films

Radical Anions of Mono- and Bis-fulleropyrrolidines: An EPR Study

Discrete Fulleride Anions and Fullerenium Cations

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Femtosecond Dynamics of Photoexcited C₆₀ Films

Femtosecond Dynamics of Photoexcited C₆₀ Films