Homodesmotic reaction for fullerenes

The ASE (aromatic stabilization energy) for C₆₀ and C₇₀ have been evaluated by a new homodesmotic reaction and the results support the early established fact that C₇₀ is more stable than C₆₀.     

Metalloporphyrin hosts for supramolecular chemistry of fullerenes

This paper is a tutorial review of the host-guest chemistry of fullerenes and metalloporphyrin. Among various host molecules for fullerenes, cyclic hosts composed of metalloporphyrin moieties possess one of the highest affinities toward fullerenes, which can be widely tuned simply by changing the central metal ions of the porphyrin moieties. Inclusion of fullerenes occurs not only by van der Waals interactions but also, in some cases, via pi-electronic charge-transfer from the host metalloporphyrin moieties to the guest fullerenes. Fullerenes such as C(120), upon inclusion with cyclic metalloporphyrin dimers, show an oscillatory motion within the host cavity, whose frequency reflects the solvation/desolvation dynamics of the fullerenes. A molecularly engineered metalloporphyrin host with a self-assembling capability allows a guest-directed formation of a supramolecular peapod, where included fullerenes, as peas, are aligned along the self-assembled metalloporphyrin nanotube, as a pod. Furthermore, certain metalloporphyrin hosts are applicable to the selective extraction of low-abundance higher fullerenes from an industrial production source and also allow spectroscopic discrimination of chiral fullerenes.     

Methods for the chemical synthesis of fullerenes

C(60) has been synthesized by chemical methods in 12 steps. Lessons learned in the author's laboratory during a decade devoted to the synthesis and study of open geodesic polyarenes strongly influenced the strategy and methodology ultimately employed for preparing a suitable 60-carbon precursor and for closing it up to the fullerene ball. This review provides a personal account of how the new synthetic tools were developed and put to use.     

Transmutation of fullerenes

Fullerenes were pyrolyzed by subliming them into a stream of flowing argon gas and then passing them through an oven heated to approximately 1000 degrees C. C(76), C(78), and C(84) all readily lost carbons to form smaller fullerenes. In the case of C(78), some isomerization was seen. Pyrolysis of (3)He@C(76) showed that all or most of the (3)He was lost during the decomposition. C(60) passes through the apparatus with no decomposition and no loss of helium.     

Experimental evidence for the photoisomerization of higher fullerenes

The initial relaxation dynamics of the photoexcited fullerenes C60, C70, C76, C84, C86, and C90 were investigated by dispersion-free femtosecond pump-probe spectroscopy. Under identical excitation conditions, the formation of the lowest excited state slows down for the larger fullerenes. This trend in dynamics, monitored throughout the visible and NIR range, is found to correlate with the number of isomers in accordance with the isomerization mechanism suggested by Stone and Wales. The Stone-Wales isomerization was calculated as thermally inaccessible but photoinduced barrierless. The energy difference of the isomers is in the 1 meV range, and back-isomerization is observed on the picosecond time scale. The characteristic spectrally broad transient absorption of the investigated fullerenes is promising for fast optical gating applications.     

Technology for manufacture of pure fullerenes C60, C70 and a concentrate of higher fullerenes

An integrated technology for manufacture of fullerenes was developed. It includes the following stages: synthesis of a fullerene black, extraction of a mixture of fullerenes from the black, preliminary separation of the mixture into concentrates enriched in C₆₀ and C₇₀ fullerenes, and production of C₆₀ and C₇₀ fullerenes of purity exceeding 99.5 and 98.0 wt %, respectively, from the concentrates.     

碳笼化学 1

本文介绍并评述了碳笼化学的最新进展, 指出这是一个前景十分诱人的现代化学新兴领域。     

Increasing cost of pentagon adjacency for larger fullerenes

The cost of a pentagon adjacency in a fullerene cage grows linearly from 72 kJ mol⁻¹ for C₃₀ to 111 kJ mol⁻¹ for C₆₀, according to systematic QCFF/PI model calculations on a set of 2624 structural isomers.     

Reactivity of boron fullerenes

The properties of carbon and boron fullerenes are compared, and similarities and distinctions are pointed out. The ionization potentials and electron affinities of boron nanoparticles are estimated, and the binding energy for these systems is calculated.     

Chirality of toroidal molecular graphs

Symmetry properties of a class of toroidal molecular graphs, arising as covers of certain bipartite cubic Cayley graphs of dihedral groups, are studied. Although these symmetries make all vertices and all edges indistinguishable, they imply intrinsic chirality.     

New structural parameters of fullerenes for principal component analysis

The Kekulé structure count and the permanent of the adjacency matrix of fullerenes are related to structural parameters involving the presence of contiguous pentagons p, q, r, q/p and r/p, where p is the number of edges common to two pentagons, q is the number of vertices common to three pentagons and r is the number of pairs of nonadjacent pentagons adjacent to another common pentagon. The cluster analysis of the structural parameters allows classification these parameters. Principal component analysis (PCA) of the structural parameters and the cluster analyses of the fullerenes permit their classification. PCA clearly distinguishes five classes of fullerenes. The cluster analysis of fullerenes is in agreement with PCA classification. Cluster analysis shows greatest similarity for the q–q/p and r–r/p pairs. PCA provides five orthogonal factors F ₁–F ₅. The use of F ₁ gives an error of 28%. The inclusion of F ₂ decreases the error to 2%.From the Proceedings of the 28th Congreso de Químicos Teóricos de Expresión Latina (QUITEL 2002)     

Oxidation of fullerenes with ozone

Heterophase and liquid-phase oxidation reactions of fullerene with ozone and the data on chemiluminescence generated in these reactions were considered and classified for the first time.     

On decompositions of leapfrog fullerenes

It is shown that given a fullerene F with the number of vertices n divisible by 4, and such that no two pentagons in F share an edge, the corresponding leapfrog fullerene Le(F) contains a long cycle of length 3n − 6 missing out only one hexagon.     

Aziridinofullerene: a versatile platform for functionalized fullerenes

An aziridine moiety on the fullerene core can serve as an acid-triggered reacting template for the controlled synthesis of a range of functionalized fullerenes that are otherwise difficult to synthesize in an efficient and selective manner. A copper-catalyzed aziridination of C(60) for the practical synthesis of aziridinofullerene 1 and acid-catalyzed reactions of 1 with mono- and bifunctional nucleophiles as well as alkynes are described. The rapid generation of structural diversity in a single chemical operation using the common platform 1 is notable.     

Direct delocalization for calculating electron transfer in fullerenes

A method is introduced for simple calculation of charge transfer between very large solvated organic dimers (fullerenes here) from isolated dimer calculations. The individual monomers in noncentrosymmetric dimers experience different chemical environments, so that the dimers do not necessarily represent bulk‐like molecules. Therefore, we apply a delocalizing bias directly to the Fock matrix of the dimer system, and verify that this is almost as accurate as self‐consistent solvation. As large molecules like fullerenes have a plethora of excited states, the initially excited state orbitals are thermally populated, so that the rate is obtained as a thermal average over Marcus thermal transfers. © 2013 Wiley Periodicals, Inc.