Reaction studies of carbon clusters

Hallett, R.; McKay, K. G.; Balm, S. P.; Allaf, A.W.; Kroto, Harold W.; Stace, A. J.

doi:10.1007/bf01443738

Cited by 13 publications

(5 citation statements)

References 38 publications

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“…Hallett et al 10 have studied the carbon clusters in the range n ) 8-37, produced by laser vaporization in a supersonic nozzle and investigated with time-of-flight (TOF) mass spectrometry confirming the existence of C 26 , C 28 , and other small fullerenes. C 28 fullerene has been known to be the smallest fullerene molecule and becomes stable as M@C 28 (M ) Ti, Mg, etc.).…”

Section: Methodsmentioning

confidence: 99%

Quantum Chemical AM1 Treatment of the Circumscribing Algorithm: Fullerene Growth Mechanism

Mishra¹,

Lin²,

Lee³

1999

J. Chem. Inf. Comput. Sci.

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A graph theoretically formulated circumscribing algorithm for the fullerene growth mechanism has been analyzed using the quantum chemical AM1 method. Following different routes, two small fullerenes C 28 (T d and D 2 ) and C 26 (D 3h ) have been constructed from monocyclic/polycyclic precursors and circumscribed with appropriate carbon belts. The deformation energies (DE) and the average bond lengths 〈R〉 of the precursors have been computed. The DE values suggest that there is a chance of bond cleavage of the polycyclic precursors as the growth process proceeds toward the cage formation. On the other hand, the monocyclic precursors are found to have significantly lower deformation energies than the polycyclic precursors. Further, with analysis of 〈R〉 values of the polycyclic and monocyclic cases at different stages, it is observed that the 〈R〉 values of the polycyclic cases decrease gradually, depicting a shrinkage in the precursors which may be detrimental to the growth process, whereas monocyclic precursors tend to swell, corroborating the tendency of the system to grow which may be conducive for the growth process.Low-mass fullerenes possessing high curvature and increased strain owing to the presence of adjacent pentagonal rings could lead to solids with unusual intermolecular bonding and electronic properties.1 The recent synthesis 1 of macroscopic quantities of solid fullerene C 36 might be viewed as another milestone in the study of fullerene chemistry. The C 36 fullerene synthesis begs the question of a possible synthesis of even smaller fullerenes than C 36 . After the epoch making discovery of C 60 (Buckminsterfullerene 2 ) in 1985, fullerene chemistry had to wait reluctantly for 6 more years until C 60 was synthesized in bulk quantity for the full experimental characterization. 3 At that juncture the progress in the characterization of the lower fullerenes is considered to be only of theoretical interest. But, now with the synthesis of C 36 by Piskoti et al., 1 a new area in the lower fullerene domain has emerged. Though fullerene is now wellrecognized as an attractive new material and numerous reports regarding its applications have been proposed, the mechanism of how such a symmetric hollow cage structure can be self-assembled has remained as an intriguing problem.In recent years, several attempts have been made both theoretically and experimentally in order to unveil the mystery of fullerene growth mechanism. Experiments on resistive evaporation of two carbon rods with different degrees of enrichment in 13 C have revealed that the carbon vapor consists of smaller clusters before the process of fullerene formation starts. 4 Further, experimental gas ion chromatography studies of the structure of the carbon clusters lead to the formation of the possible paths of fullerene formation through the coagulation of monocycles and gradual transformations of polycyclic structures into fullerene cages. 5-7These elementary carbon clusters such as monocyclic rings or polycyclic rings are termed as precursors 5,...

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Section: Methodsmentioning

confidence: 99%

Quantum Chemical AM1 Treatment of the Circumscribing Algorithm: Fullerene Growth Mechanism

Mishra¹,

Lin²,

Lee³

1999

J. Chem. Inf. Comput. Sci.

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“…302 In some of these studies, information about the neutral structures was obtained by seeding the reactant in the carrier gas of a laser vaporizationsupersonic expansion source. [294][295][296] Neutral species formed in the expansion were then ionized and observed using time-of-flight mass spectrometry. Long polyacetylenic chains (HC n H, n e 40) were thought to be present with H 2 as the reactant gas, leading to the conjecture that neutral carbon chains of this size may be forming.…”

Section: Ion−molecule Reactivity Studiesmentioning

confidence: 99%

“…These studies of course provide much useful information about the ion−molecule chemistry of carbon cluster ions. In recent years, carbon cluster cation structural and reactive properties have been investigated by reactions with such species as H 2 , − O 2 , N 2 O, − benzene, naphthalene, nitriles, , chloropropenes, and polyaromatic hydrocarbons . Pozniak and Dunbar recently showed that C 10 + to C 24 + ions whose cyclic isomers satisfied the conditions for aromaticity were less reactive than the other ions in this size range …”

Section: Ion−molecule Reactivity Studiesmentioning

confidence: 99%

Small Carbon Clusters: Spectroscopy, Structure, and Energetics

1998

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“…Consensus of opinion now favours closed shell fullerene structures for the C32-C 100 clusters, with each containing, by definition, the twelve pentagons required for closure (Euler's rule) plus (n -20)/2 hexagons. There is now convincing all fullerenes (C20, C24 ...) may form from graphite (Kroto 1987;Hallet et al 1992), however, the mechanism is very much an open question, with concrete evidence hard to come by. One possibility would be for long polyyne chains, formed from C2 or C4 units, to spirocyclize forming a complete or part fullerene.…”

Section: Fullerenes From Polyynesmentioning

confidence: 99%

Polyynes and the formation of fullerenes

Kroto

Walton

Jones³

et al. 1993

Phil. Trans. R. Soc. Lond. A

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The synthesis and microwave study of linear cyanopolyynes, HC 5 N and HC 7 N, in the mid-1970s was followed by the unanticipated detection of these, and longer chains (HC 9 N and HC 11 N), in space. To gain insight into the way in which such species and carbon clusters in general might form, an experiment was devised in 1985 to simulate conditions in carbon stars, involving the laser vaporization of graphite in a supersonic nozzle and detection of the resulting carbon species by mass spectrometry. This initiative resulted in the serendipitious discovery of an entirely new allotrope of carbon, C 60 , named buckminsterfullerene after the inventor of the geodesic dome. Five to seven years later, C 60 and other members of what is now know as the fullerene family have been isolated in macroscopic amounts, however, these exciting developments have tended to overshadow fundamental problems associated with the aggregation of carbon atoms in which acetylenes, and polyynes in particular, may play a key role.

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Reaction studies of carbon clusters

Cited by 13 publications

References 38 publications

Quantum Chemical AM1 Treatment of the Circumscribing Algorithm: Fullerene Growth Mechanism

Quantum Chemical AM1 Treatment of the Circumscribing Algorithm: Fullerene Growth Mechanism

Small Carbon Clusters: Spectroscopy, Structure, and Energetics

Polyynes and the formation of fullerenes

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