Fullerene Isomerism: Isolation of
 C
 
 2
 v
 
 ,-C
 78
 and
 D
 3
 -C
 78

Diederich, François; Whetten, Robert L.; Thilgen, Carlo; Ettl, Roland; Chao, Ito; Alvarez, Marcos M.

doi:10.1126/science.254.5039.1768

Cited by 382 publications

(181 citation statements)

References 21 publications

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“…The final transposition of 5-and 6-membered rings from 32 to 17, on the other hand, simply represents a special case of the acenaphthylene bond-switch rearrangement already discussed (cf: Scheme 12). It is interesting to note, with respect to fullerene chemistry, that the 32 -> 17 transformation can be viewed as an "annealing mechanism" by which this tetracyclic C14l-I~ system can satisfy the "isolated pentagon rule" (36,37,38) (39,40). These authors have actually suggested a more circuitous mechanistic pathway from 33 to 34, but the evidence is equally compatible with the one-step isomerization in Scheme 18.…”

Section: (23)mentioning

confidence: 99%

Fragments of fullerenes: Novel syntheses, structures and reactions

Scott¹

1996

Pure and Applied Chemistry

342

150

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Abstract. The utility of high-temperature gas-phase cyclization reactions for constructing bowl-shaped polycyclic aromatic hydrocarbons related to C6o was first demonstrated by our simple synthesis of corannulene, 1. This strategy has subsequently been extended to the preparation of larger fullerene fragments and promises to play a central role in future syntheses of even more spectacular molecular bowls, baskets and tubes. Isomerization reactions of benzenoid hydrocarbons at high temperatures in the gas phase have also been studied and are now known to occur by reversible benzene ring contractions to fulvene intermediates. The relationship of these small molecule rearrangements to the mechanisms of fullerene production and isomerization ("annealing") is discussed. Finally, the conversion of simple benzenoid hydrocarbons to fragments of fullerenes containing fivemembered rings with two hydrogens fewer is shown to be a common high-temperature reaction of bay region polycyclic aromatic compounds, and a preliminary mechanistic proposal is offered along with supporting experimental evidence.The landmark synthesis of corannulene, 1, by Barth and Lawton was first announced in 1966 (l), more than two decades prior to the earliest preparative synthesis of C a and the higher fullerenes (2). This marvelous bowl-shaped C20H10 hydrocarbon represents the minimal structural subunit of a fullerene that retains a curved network of trigonal carbon atoms, and recent years have witnessed a resurgence of interest in corannulene and the larger fragments of fullerenes (3,4). My coworkers and I have been actively engaged in this area of research since 1990, and the first section of this paper presents an overview of our syntheses and selected transformations of bowl-shaped polycyclic aromatic hydrocarbons (PAHs). The latter portion of the paper describes some of our findings on the high temperature chemistry of PAHs that we believe provide insight into the mechanism of formation and isomerization of fullerenes.Buckminsterfullerene C, Corannulene 1 Strategies for Constructing Bowl-Shaped Fragments of FullerenesHow can one fashion a curved network of trigonal carbon atoms when all the constituent atoms have a natural tendency to remain planar? Any rational synthesis of a bowl-shaped fullerene fragment must overcome the angle strain associated with pyramidalization of numerous sp2 hybridized carbon atoms. Barth and Lawton solved this problem by first putting together the entire carbon skeleton of corannulene with very few centers of unsaturation and then aromatizing the rings in the final step (1,5). Our approach, on the other hand, is completely different. Inspired by the recognition that fullerenes, the most strikingly curved networks of trigonal carbon atoms, can be formed under high energy conditions in the gas phase (2, 6), we reasoned that it should be possible to capitalize on the principles at work there for a new synthesis of corannulene and related fragments of fullerenes. Toward this end, we prepared 7,1O-diethynylfluoranthene...

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Section: (23)mentioning

confidence: 99%

Fragments of fullerenes: Novel syntheses, structures and reactions

Scott¹

1996

Pure and Applied Chemistry

342

150

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“…The D 3h -C 78 (4) isomer possesses the lowest stability; it has never been found in the fullerene soot. These differences are satisfactorily explained by the differences in the relative formation energies of the C 78 (1) -C 78 (5) isomers [3].…”

Section: Introductionmentioning

confidence: 60%

“…The abundances of C 78 (1) -C 78 (3) isomers in the fullerene soot are comparable, being dependent on the method of fullerene synthesis [3,4]. The D 3 -C 78 (1) and C 2v -C 78 (2) isomers were isolated chromatographically and their cage structures were confirmed by 13 C NMR spectroscopy [3]. At the same time, isomer D 3h -C 78 (5) is elusive because of a small band gap resulting in a very low solubility; its presence in the fullerene soot could be unambiguously confirmed by the structural study of a CF 3 derivative, C 78 (5)(CF 3 ) 12 [5].…”

Section: Introductionmentioning

confidence: 80%

“…The C 78 (2) -C 78 (5) isomers can be converted into each other by Stone -Wales rearrangements (SWR) of the pyracylene type, whereas C 78 (1) cannot be transformed into other isomers of C 78 by SWRs. The abundances of C 78 (1) -C 78 (3) isomers in the fullerene soot are comparable, being dependent on the method of fullerene synthesis [3,4]. The D 3 -C 78 (1) and C 2v -C 78 (2) isomers were isolated chromatographically and their cage structures were confirmed by 13 C NMR spectroscopy [3].…”

Section: Introductionmentioning

confidence: 85%

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Synthesis, isolation, and X-ray structural characterization of trifluoromethylated C78 fullerenes: C78(2)(CF3)10/12 and C78(3)(CF3)12/14

Tamm¹,

Kosaya²,

Fritz³

et al. 2016

Nanosystems: Phys. Chem. Math.

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Four CF 3 derivatives of C 78 , C 78 (2)(CF 3 ) 10/12 and C 78 (3)(CF 3 ) 12/14 , have been isolated via HPLC from the products of high-temperature trifluoromethylation of a C 76 -C 96 fullerene mixture or a C 78 fraction. Their molecular structures were determined by single crystal X-ray crystallography using synchrotron radiation. The addition patterns of the new compounds are compared with each other and with the previously known C 78 (2)(CF 3 ) 10 and C 78 (3)(CF 3 ) 12 .

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“…Besides CgQ, larger fuUerene clusters can also be isolated from the soot [42,43,44,45,46], but the structures of many of these large fuUerenes are stiU not clear.…”

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confidence: 99%

Theoretical studies of zirconium and carbon clusters with molecular dynamics simulations

Zhang

1993

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Zhang, Bulin, "Theoretical studies of zirconium and carbon clusters with molecular dynamics simulations " (1993 INFORMATION TO USERSThis manuscript has been reproduced from the microfilm master, UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer.The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely afreet reproduction.In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion.Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand corner and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book.

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Fullerene Isomerism: Isolation of C _{2
v} ,-C ₇₈ and D ₃ -C ₇₈

Cited by 382 publications

References 21 publications

Fragments of fullerenes: Novel syntheses, structures and reactions

Fragments of fullerenes: Novel syntheses, structures and reactions

Synthesis, isolation, and X-ray structural characterization of trifluoromethylated C78 fullerenes: C78(2)(CF3)10/12 and C78(3)(CF3)12/14

Theoretical studies of zirconium and carbon clusters with molecular dynamics simulations

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Fullerene Isomerism: Isolation of C 2 v ,-C 78 and D 3 -C 78

Cited by 382 publications

References 21 publications

Fragments of fullerenes: Novel syntheses, structures and reactions

Fragments of fullerenes: Novel syntheses, structures and reactions

Synthesis, isolation, and X-ray structural characterization of trifluoromethylated C78 fullerenes: C78(2)(CF3)10/12 and C78(3)(CF3)12/14

Theoretical studies of zirconium and carbon clusters with molecular dynamics simulations

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Fullerene Isomerism: Isolation of C _{2
v} ,-C ₇₈ and D ₃ -C ₇₈