Electronic structures, stabilities, and spectroscopies of the fullerene derivatives C68X4 (X=H, F, Cl)

Xu, Lei; Shao, Xueguang; Cai, Wensheng

doi:10.1016/j.theochem.2010.01.002

Cited by 5 publications

(5 citation statements)

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“…At a temperature above 2,100 K, however, the heptagon-incorporating C 68 becomes the most abundant species as entropic factors have a decisive role in their relative Gibbs free energies and relative concentrations/abundances (Supplementary Tables S8 and S9). In agreement with this prediction about the temperature-dependent stability, several theoretical studies have suggested the prevalence of heptagons in the world of the cage-closed all-carbon allotropes1112131415161718192021232425263536. Experimental corroboration of such a prevalence of heptagons heavily depends on the in situ capture of heptafullerene in the carbon clustering venue for the growth of the whole family of fullerenes.…”

Section: Discussionmentioning

confidence: 64%

“…Heptafullerene[72], which has been predicted by Akasaka and Nagase 21 from 431,240 isomeric possibilities, is more stable than the Isolated Pentagon Rule 22 satisfying isomer in form of endofullerene Ca@C 72 . A bare heptafullerene[62] with C s -symmetry 23 , as well as the exohedral heptagon-containing C 68 X 4 (X=H, F, Cl) 24 , has been calculated to be more stable than all the classical non-heptagon isomers. Very recently, a number of smaller heptafullerenes (C 46 –C 58 ) have also been suggested to be viable 18 25 26 .…”

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confidence: 99%

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Carbon arc production of heptagon-containing fullerene[68]

et al. 2011

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A carbon heptagon ring is a key unit responsible for structural defects in sp2-hybrized carbon allotropes including fullerenes, carbon nanotubes and graphenes, with consequential influences on their mechanical, electronic and magnetic properties. Previous evidence concerning the existence of heptagons in fullerenes has been obtained only in off-line halogenation experiments through top-down detachment of a C2 unit from a stable fullerene. Here we report a heptagon-incorporating fullerene C68, tentatively named as heptafullerene[68], which is captured as C68Cl6 from a carbon arc plasma in situ. The occurrence of heptagons in fullerenes is rationalized by heptagon-related strain relief and temperature-dependent stability. 13C-labelled experiments and mass/energy conservation equation simulations show that heptafullerene[68] grows together with other fullerenes in a bottom-up fashion in the arc zone. This work extends fullerene research into numerous topologically possible, heptagon-incorporating isomers and provides clues to an understanding of the heptagon-involved growth mechanism and heptagon-dependent properties of fullerenes.

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Section: Discussionmentioning

confidence: 64%

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confidence: 99%

Carbon arc production of heptagon-containing fullerene[68]

et al. 2011

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“…Because of its interesting electronic properties, thiophene-based derivatives revealed to be promising molecules for SONLO purposes. − Thus, the presence of redox-active metal centers together with a thiophene-based conjugated framework provides good opportunities for modulation of molecular NLO responses and is hence a primary justification for the study of these systems. In recent years, our group has focused in the study of intrinsic hyperpolarizabilities of η 5 -monocyclopentadienyliron(II)/ruthenium(II) complexes presenting thiophene conjugated ligands coordinated to the metal center through nitrile or acetylide linkages. − Our ongoing work in this field was attracted by benzo[ c ]thiophene-based chromophores, whose unique electronic behavior originated by their low HOMO–LUMO energy gaps can be potentially on the basis of strong NLO effects. , …”

Section: Introductionmentioning

confidence: 99%

Switchable Nonlinear Optical Properties of η⁵-Monocyclopentadienylmetal Complexes: A DFT Approach

Mendes

Silva

Garcia

et al. 2012

J. Chem. Inf. Model.

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Density functional theory (DFT) calculations have been carried out to investigate the switching of the second-order nonlinear optical (NLO) properties of η(5)-monocyclopentadienyliron(II) and ruthenium(II) model complexes presenting 5-(3-(thiophen-2-yl)benzo[c]thiophen-1-yl)thiophene-2-carbonitrile as a ligand. The switching properties were induced by redox means. Both oxidation and reduction stimulus have been considered, and calculations have been performed both for the complexes and for the free benzo[c]thiophene derivative ligand in order to elucidate the role played by the organometallic fragment on the second-order NLO properties of these complexes. B3LYP, CAM-B3LYP, and M06 functionals were used for our calculations. The results show some important structural changes upon oxidation/reduction that are accompanied by significant differences on the corresponding second-order NLO properties. TD-DFT calculations show that these differences on the second-order NLO response upon oxidation/reduction are due to a change in the charge transfer pattern, in which the organometallic iron and ruthenium moieties play an important role. The calculated static hyperpolarizabilities were found to be strongly functional dependent. CAM-B3LYP, however, seems to predict more reliable structural and optical data as well as hyperpolarizabilities when compared to experimental data. The use of this functional predicts that the studied complexes can be viewed as acting as redox second-order NLO switches, in particular using oxidation stimulus. The β(tot) value of one-electron oxidized species is at least ~8.3 times (for Ru complex) and ~5.5 times (for Fe complex) as large as that of its nonoxidized counterparts.

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“…Nagase et al’s theoretical investigation with DFT methods demonstrated that a Ca@C 72 isomer whose carbon cage was a nonclassical heptagon-containing one was the most stable isomer of the Ca@C 72 series . Cai and co-workers proved that the nonclassical C 68 exohedral derivatives C 68 X 4 (X = H, F, and Cl) were more stable than the classical counterparts by first-principles calculation . These theoretical investigations suggest that nonclassical fullerene and derivatives can be synthesized.…”

Section: Introductionmentioning

confidence: 99%

“…30 Cai and co-workers proved that the nonclassical C 68 exohedral derivatives C 68 X 4 (X = H, F, and Cl) were more stable than the classical counterparts by first-principles calculation. 31 These theoretical investigations suggest that nonclassical fullerene and derivatives can be synthesized.…”

Section: ■ Introductionmentioning

confidence: 99%

How to Stabilize a Heptagon-Containing C₈₀Cage by Endohedral Derivation

2020

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Nonclassical fullerene is a new member of the fullerene family. In the present work, a systematic investigation on La x Sc 3−x N@C 80 (x = 0−3) covering both classical and nonclassical C 80 cages was performed utilizing density functional theory combined with statistical mechanics. At absolute zero, LaSc 2 N@Hept(6)-C s (2)-C 80 with a heptagon-containing nonclassical carbon is the second most stable isomer, whereas at the temperature range of endohedral metallofullerene (EMF) formation, due to the large vibrational frequencies, LaSc 2 N@Hept(6)-C s (2)-C 80 is the third most abundant isomer, and its mole fraction is very low, accounting for the low experimental yield of LaSc 2 N@Hept(6)-C s (2)-C 80 ; La 2 ScN@Hept(6)-C s (2)-C 80 , and La 3 N@Hept(6)-C s (2)-C 80 are the overwhelming isomers of the corresponding series, but compared with the cases of Sc 3 N@C 80 and LaSc 2 N@C 80 , La 2 ScN and La 3 N clusters suffer much larger constraints from the C 80 cages, perhaps preventing the synthesis of La 2 ScN@C 80 and La 3 N@C 80 species. Because of the large mole fractions and large electron donation and back-donation of La 2 ScN@Hept(6)-C s (2)-C 80 and La 3 N@Hept(6)-C s (2)-C 80 , it can be inferred that La 2 ScN and La 3 N clusters may be used to stabilize some other larger nonclassical fullerene cages. This work will provide useful insights into the origins of stabilization of nonclassical fullerene cages by endohedral derivation and guidelines for synthesis EMF with nonclassical cages.

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Electronic structures, stabilities, and spectroscopies of the fullerene derivatives C68X4 (X=H, F, Cl)

Cited by 5 publications

References 35 publications

Carbon arc production of heptagon-containing fullerene[68]

Carbon arc production of heptagon-containing fullerene[68]

Switchable Nonlinear Optical Properties of η⁵-Monocyclopentadienylmetal Complexes: A DFT Approach

How to Stabilize a Heptagon-Containing C₈₀Cage by Endohedral Derivation

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Electronic structures, stabilities, and spectroscopies of the fullerene derivatives C68X4 (X=H, F, Cl)

Cited by 5 publications

References 35 publications

Carbon arc production of heptagon-containing fullerene[68]

Carbon arc production of heptagon-containing fullerene[68]

Switchable Nonlinear Optical Properties of η5-Monocyclopentadienylmetal Complexes: A DFT Approach

How to Stabilize a Heptagon-Containing C80Cage by Endohedral Derivation

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Switchable Nonlinear Optical Properties of η⁵-Monocyclopentadienylmetal Complexes: A DFT Approach

How to Stabilize a Heptagon-Containing C₈₀Cage by Endohedral Derivation