A global search for the lowest energy isomer of C(26)

From C(58) to C(62) and back: Stability, structural similarity, and ring current

An increasing number of observations show that non-classical isomers may play an important role in the formation of fullerenes and their exo- and endo-derivatives. A quantum-mechanical study of all classical isomers of C₅₈ , C₆₀ , and C₆₂ , and all non-classical isomers with at most one square or heptagonal face, was carried out. Calculations at the B3LYP/6-31G* level show that the favored isomers of C₅₈ , C₆₀ , and C₆₂ have closely related structures and suggest plausible inter-conversion and growth pathways among low-energy isomers. Similarity of the favored structures is reinforced by comparison of calculated ring currents induced on faces of these polyhedral cages by radial external magnetic fields, implying patterns of magnetic response similar to those of the stable, isolated-pentagon C₆₀ molecule. © 2016 Wiley Periodicals, Inc.

Ab initio infrared vibrational modes for neutral and charged small fullerenes (C20, C24, C26, C28, C30 and C60)

We calculate the infrared (IR) absorption spectra using DFT B3LYP(6-311G) for a range of small closed-cage fullerenes, Cn, n=20, 24, 26, 28, 30 and 60, in both neutral and multiple positive and negative charge states. The results are of use, notably, for direct comparison with observed IR absorption in the interstellar medium. Frequencies fall typically into two ranges, with C-C stretch modes around 1100-1500 cm(-1) (6.7-9.1 μm) and fullerene-specific radial motion associated with under-coordinated carbon at pentagonal sites in the range 600-800 cm(-1) (12.5-16.7 μm). Notably, negatively charged fullerenes show significantly stronger absorption intensities than neutral species. The results suggest that small cage fullerenes, and notably metallic endofullerenes, may be responsible for many of the unassigned interstellar IR spectral lines.This article is part of the themed issue 'Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene'.

Systematic Construction and Calculation of Electronic Properties of Fullerene Series Related by Rotational Symmetry: From Fullerenes to Bicapped Nanotubes

The results herein demonstrate that the methods of circumscribing and the facile calculation of Hückel molecular orbital (HMO) eigenvalues by mirror-plane fragmentation have a broad application in the construction of carbon cluster series and the systematic study of trends in their electronic properties. In comparing open-ended nanotubes and their isomeric elongated fullerenes (bicapped nanotubes), we show that the former are more aromatic but the latter are more conjugated and that progressive elongation increases aromaticity and conjugation in both. Recursion equations that will allow one to obtain the eigenvalues to all 5-endcapped nanotubes are given.

Electronic properties and photoactivity of monolayer MoS2/fullerene van der Waals heterostructures

van der Waals (vdW) heterostructures have attracted immense interest recently due to their unusual properties and new phenomena.

Enhanced photocatalytic performance of an Ag3PO4 photocatalyst via fullerene modification: first-principles study

The coupling of carbon nanomaterials with semiconductor photocatalysts is a promising route to improve their photocatalytic performance.

The topology of fullerenes

Fullerenes are carbon molecules that form polyhedral cages. Their bond structures are exactly the planar cubic graphs that have only pentagon and hexagon faces. Strikingly, a number of chemical properties of a fullerene can be derived from its graph structure. A rich mathematics of cubic planar graphs and fullerene graphs has grown since they were studied by Goldberg, Coxeter, and others in the early 20th century, and many mathematical properties of fullerenes have found simple and beautiful solutions. Yet many interesting chemical and mathematical problems in the field remain open. In this paper, we present a general overview of recent topological and graph theoretical developments in fullerene research over the past two decades, describing both solved and open problems. WIREs Comput Mol Sci 2015, 5:96-145. doi: 10.1002/wcms.1207 Conflict of interest: The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website.

Carbon arc production of heptagon-containing fullerene[68]

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.

Chemical manipulation of fullerenes has allowed the production of heptagon-containing fullerenes, but they have not been synthesised using bottom-up approaches. Here, a heptagon-containing fullerene[68] is obtained as C₆₈Cl₆ from a carbon arc plasma.