C 60 + defect centers: effect of rubidium intercalation into C 60 studied by EPR

Kempiński, W.; Piekara-Sady, L.; Katz, Eugene A.; Shames, Alexander I.; Shtutina, S.

doi:10.1016/s0038-1098(00)00014-4

Cited by 15 publications

(21 citation statements)

References 12 publications

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“…This effect was confirmed by a solid-state dilution experiment where the Gd 2 @C 79 N sample was mixed with an empty cage fullerene C 60 (ratio of C 60 : Gd 2 @C 79 N ∼9:1, See SI). There is a small sharp peak with the observed g-factor (g 0 =2.001), which has been previously reported as defect sites in C 60 cages 30 (See SI). The ambient temperature EPR spectrum of the solution and mixed solid sample suggests considerable motional averaging motion of the Gd 2 @C 79 N molecule and/or Gd-Gd cluster motional averaging in the C 60 solid matrix without an observable nuclear hyperfine interaction.…”

Section: Resultssupporting

confidence: 67%

Gd₂@C₇₉N: Isolation, Characterization, and Monoadduct Formation of a Very Stable Heterofullerene with a Magnetic Spin State of S = 15/2

et al. 2011

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The dimetallic endohedral heterofullerene (EHF), Gd2@C79N, was prepared and isolated in a relatively high yield when compared with the earlier reported heterofullerene, Y2@C79N. Computational (DFT), chemical reactivity, Raman, and electrochemical studies all suggest that the purified Gd2@C79N, with the heterofullerene cage, (C79N)5- has comparable stability with other better known isoelectronic metallofullerene (C80)6- cage species (e.g., Gd3N@C80). These results describe an exceptionally stable paramagnetic molecule with low chemical reactivity with the unpaired electron spin density localized on the internal diatomic gadolinium cluster and not on the heterofullerene cage. EPR studies confirm that the spin state of Gd2@C79N is characterized by a half-integer spin quantum number of S = 15/2. The spin (S = 1/2) on the N atom of the fullerene cage and two octet spins (S = 7/2) of two encapsulated gadoliniums are coupled with each other in a ferromagnetic manner with a small zero-field splitting parameter D. Because the central line of Gd2@C79N is due to the Kramer's doublet with a half-integer spin quantum number of S = 15/2, this relatively sharp line is prominent and the anisotropic nature of the line is weak. Interestingly, in contrast with most Gd3+ ion environments, the central EPR line (g=1.978) is observable even at room temperature in a toluene solution. Finally, we report the first EHF derivative, a diethyl bromomalonate monoadduct of Gd2@C79N, was prepared and isolated via a modified Bingel-Hirsch reaction.

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Section: Resultssupporting

confidence: 67%

Gd₂@C₇₉N: Isolation, Characterization, and Monoadduct Formation of a Very Stable Heterofullerene with a Magnetic Spin State of S = 15/2

et al. 2011

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“…Nevertheless C 60 in fuming sulfuric acid gives at least one oxidized state with g value above the free electron one [12]. Defected C + 60 centers can be also generated by the exposure of C 60 powders or thin films to air (oxygen) and/or light (visible or UV) [13][14][15][16].…”

Section: Ionsmentioning

confidence: 99%

“…This way negatively charged fullerene paramagnetic centers can be generated. The first effect of this process is the decrease of C + 60 EPR signal -the electron introduced into the system from a donor neutralizes the positively charged C 60 [16]. At the same time another EPR signal evolves due to the generation of negative C n− 60 radicals [7].…”

Section: Ionsmentioning

confidence: 99%

“…Since alkali ion radii are r K+ = 1.33Å and r Rb+ = 1.47Å, the rubidium intercalation process is much slower compared to potassium one. It enables us to determine the kinetics of the decrease of the C + 60 signal versus time of the reaction for the Rb intercalated C 60 [16]. After the first 7 h of Rb doping, besides the C signal corresponds to the Rb diffusion into the C 60 grains [16].…”

Section: Rb X C 60mentioning

confidence: 99%

“…It enables us to determine the kinetics of the decrease of the C + 60 signal versus time of the reaction for the Rb intercalated C 60 [16]. After the first 7 h of Rb doping, besides the C signal corresponds to the Rb diffusion into the C 60 grains [16]. Therefore, after 60 h, when the C [36].…”

Section: Rb X C 60mentioning

confidence: 99%

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Superconductivity of Carbon Materials - Unstable Phases

Kempiński

2004

Acta Phys. Pol. A

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Different intercalated carbon systems: K x C 60 , Rb x C 60 as well as highly oriented pyrolytic graphite + potassium with unstable structural and superconducting behavior were investigated with the EPR and magnetically modulated microwave absorption techniques. Three characteristic, well--separated EPR signals were observed for A x C 60 (A = K or Rb) systems at the early stages of doping process. We ascribed these signals to C = (18.5 ± 0.5) K (final, stable) were distinctly separated for K x C 60 system. For C 60 intercalated by rubidium a similar evolution of EPR spectrum is observed. Prior to well-defined superconducting Rb 3 C 60 phase was created, strong instabilities of the magnetically modulated microwave absorption signal were observed at the narrow part of the doping process. For potassium intercalated highly oriented pyrolytic graphite, EPR oscillations below 100 K were observed as well as Josephson hysteresis loops were registered at 5 K.

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EPR study of the crystalline polymerized phases of C₆₀

Zhilinskaya¹,

Rakhmanina²,

Davydov³

et al. 2010

Physica Status Solidi (a)

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Comparative electron paramagnetic resonance (EPR) study of the monomer and 1D (orthorhombic) and 2D (tetragonal and rhombohedral) polymerized phases of C60 has been carried out. It was shown that the concentration of paramagnetic centers (PC) depends on the phase structure. Temperature dependences of the EPR spectra enabled separation of temperature‐dependent from temperature‐independent components of the main doublet signals, which were attributed to C 60+ radical (PC1) and to conducting electrons, respectively. Additional weak EPR signals, observed for the tetragonal and rhombohedral phases, were attributed to dimer PC2 formed by coupling of two PC1. Possible models for these centers are discussed.

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C 60 + defect centers: effect of rubidium intercalation into C 60 studied by EPR

Cited by 15 publications

References 12 publications

Gd₂@C₇₉N: Isolation, Characterization, and Monoadduct Formation of a Very Stable Heterofullerene with a Magnetic Spin State of S = 15/2

Gd₂@C₇₉N: Isolation, Characterization, and Monoadduct Formation of a Very Stable Heterofullerene with a Magnetic Spin State of S = 15/2

Superconductivity of Carbon Materials - Unstable Phases

EPR study of the crystalline polymerized phases of C₆₀

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C 60 + defect centers: effect of rubidium intercalation into C 60 studied by EPR

Cited by 15 publications

References 12 publications

Gd2@C79N: Isolation, Characterization, and Monoadduct Formation of a Very Stable Heterofullerene with a Magnetic Spin State of S = 15/2

Gd2@C79N: Isolation, Characterization, and Monoadduct Formation of a Very Stable Heterofullerene with a Magnetic Spin State of S = 15/2

Superconductivity of Carbon Materials - Unstable Phases

EPR study of the crystalline polymerized phases of C60

Contact Info

Product

Resources

About

Gd₂@C₇₉N: Isolation, Characterization, and Monoadduct Formation of a Very Stable Heterofullerene with a Magnetic Spin State of S = 15/2

Gd₂@C₇₉N: Isolation, Characterization, and Monoadduct Formation of a Very Stable Heterofullerene with a Magnetic Spin State of S = 15/2

EPR study of the crystalline polymerized phases of C₆₀