Isolation and Characterization of a New Isomer of Ca@C72

Ichikawa, Takafumi; Kodama, Tohru; Suzuki, Satoshi; Fujii, Ryosuke; Nishikawa, Hiroyuki; Ikemoto, Isao; Kikuchi, Kôichi; Achiba, Yohji

doi:10.1246/cl.2004.1008

Cited by 30 publications

(27 citation statements)

References 7 publications

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“…Two Ca@C 72 isomers have been isolated [2,3]. Based on theoretical calculations for Ca@C 72 and Mg@C 72 , four stable isomers have been predicted for each of them.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, isolation and characterization of new endohedral fullerenes M@C₇₂ (M = Eu, Sr, Yb)

Bucher

Epple

Mende

et al. 2006

Physica Status Solidi (b)

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We report on new europium, strontium and ytterbium endohedral fullerene cages of the type Eu@C 72 , Sr@C 72 and Yb@C 72 . Single isomers of Eu@C 72 -I, Sr@C 72 -I, Sr@C 72 -II and Yb@C 72 -I were isolated by multi-step HPLC for the first time. Details of their synthesis, separation and characterization by LDI-TOF mass spectrometry and UV-vis will be discussed. Additionally, EPR spectroscopy of Eu@C 72 -I was performed. A second isomer of europium and ytterbium endohedral C 72 , Eu@C 72 -II and Yb@C 72 -II, has been separated by HPLC and identified by LDI-TOF mass spectrometry.

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“…Two Ca@C 72 isomers have been isolated [2,3]. Based on theoretical calculations for Ca@C 72 and Mg@C 72 , four stable isomers have been predicted for each of them.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, isolation and characterization of new endohedral fullerenes M@C₇₂ (M = Eu, Sr, Yb)

Bucher

Epple

Mende

et al. 2006

Physica Status Solidi (b)

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“…In addition, to the conventional RRHO treatment with equation (1), also a modified approach to description of the encapsulate motions can be considered [39], following findings [14,16,40] that the encapsulated atoms can exercise large amplitude motions, especially so at elevated temperatures (unless the motions are restricted by cage derivatizations [41]). A simplified approach called [39] free, fluctuating, or floating encapsulate model (FEM) was suggested.…”

Section: Computationsmentioning

confidence: 99%

“…The cage was experimentally confirmed in Ca@C 74 [2], Ba@C 74 [4] and La@C 74 [8]. Obviously, with Yb@C 74 , a non-IPR cage should be involved as it is the case of Ca@C 72 [14] (empty C 72 could also not be isolated yet, possibly owing to solubility problems [2,15 -17]). …”

Section: Introductionmentioning

confidence: 99%

Computations of production yields for Ba@C₇₄ and Yb@C₇₄

Slanina

Uhlı́k

Lee

et al. 2007

Molecular Simulation

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The paper reports computations for two C 74 -based endohedrals-Ba@C 74 and Yb@C 74 . A set of six C 74 cages is considered, namely one cage with isolated pentagons, three isomers with a pentagon -pentagon junction, two structures with one pentagon -pentagon pair and one heptagon. However, the endohedral based on the cage with isolated pentagons is the most important species in both systems. Special interest is paid to the Gibbs energy-based evaluations of the production abundances for different metallofullerenes, for the first time including saturated metal pressures into consideration. The computations show that the saturated metal pressures can substantially modulate the production yields.

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“…Achiba et al [62] isolated a second isomer of Ca@C 72 so that it is clear that at least one of the two available Ca@C 72 isomers [18,62] has a non-IPR cage.…”

Section: Note Added In Proofmentioning

confidence: 99%

Gibbs energy-based treatment of metallofullerenes: Ca@C₇₂, Ca@C₇₄, Ca@C₈₂, and La@C₈₂

Slanina

Adamowicz

Kobayashi

et al. 2005

Molecular Simulation

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The paper surveys ongoing computations on endohedral fullerene systems, combining the treatments of quantum chemistry and statistical mechanics. Relative concentrations of four isomers of Ca@C 72 , six isomers of Ca@C 74 , nine isomers of Ca@C 82 , and four isomers of La@C 82 are evaluated using the Gibbs energy based on density-functional theory (DFT) computations. The results illustrate the enthalpy -entropy interplay in the systems produced under high temperatures. Approximations for description of the encapsulate motions are analyzed.

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Isolation and Characterization of a New Isomer of Ca@C72

Abstract: We isolated a new (second) isomer of Ca@C72. As a result of this discovery, it was confirmed that at least one of the two Ca@C72 isomers has a C72 cage that does not satisfy the so-called isolated pentagon rule (IPR), because C72 has only one IPR cage structure.

Cited by 30 publications

References 7 publications

Synthesis, isolation and characterization of new endohedral fullerenes M@C₇₂ (M = Eu, Sr, Yb)

Synthesis, isolation and characterization of new endohedral fullerenes M@C₇₂ (M = Eu, Sr, Yb)

Computations of production yields for Ba@C₇₄ and Yb@C₇₄

Gibbs energy-based treatment of metallofullerenes: Ca@C₇₂, Ca@C₇₄, Ca@C₈₂, and La@C₈₂

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Isolation and Characterization of a New Isomer of Ca@C72

Abstract: We isolated a new (second) isomer of Ca@C72. As a result of this discovery, it was confirmed that at least one of the two Ca@C72 isomers has a C72 cage that does not satisfy the so-called isolated pentagon rule (IPR), because C72 has only one IPR cage structure.

Cited by 30 publications

References 7 publications

Synthesis, isolation and characterization of new endohedral fullerenes M@C72 (M = Eu, Sr, Yb)

Synthesis, isolation and characterization of new endohedral fullerenes M@C72 (M = Eu, Sr, Yb)

Computations of production yields for Ba@C74 and Yb@C74

Gibbs energy-based treatment of metallofullerenes: Ca@C72, Ca@C74, Ca@C82, and La@C82

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Synthesis, isolation and characterization of new endohedral fullerenes M@C₇₂ (M = Eu, Sr, Yb)

Synthesis, isolation and characterization of new endohedral fullerenes M@C₇₂ (M = Eu, Sr, Yb)

Computations of production yields for Ba@C₇₄ and Yb@C₇₄

Gibbs energy-based treatment of metallofullerenes: Ca@C₇₂, Ca@C₇₄, Ca@C₈₂, and La@C₈₂