Seminatural Occurrence of Fullerenes

In continuation to our search of fullerenes in usual soots, sixteen additional samples of Chinese ink stick have been analyzed by HPLC. When combined with our previous results, we recognize that C₆₀-content in Chinese ink sticks decreases with time following the first order rate law. This novel observation was interpreted in terms of diffusion-dissipation of C₆₀ molecules through the solid stick.     

Time-Resolved Mass Spectrometric Studies of Fullerenes and Endohedral Fullerenes

Abstract

The energetics and dynamics of C₂ evaporations from fullerene radical cations C_n ^?+ were studied with and without ion trapping techniques. Electron space charge trapping was applied in electron ionization experiments. RF trapping in a Paul type ion source was applied for Laser MPI. Appearance energies, kinetic energy releases and metastable fractions were determined. the experimental data were modeled by finite heat bath theory (FHBT) and by RRKM/QET. Evaporation (binding) energies as well as conventional and intrinsic kinetic shifts were deduced. Our results support the following conclusions: (a) C₆₀ sits on the leading edge of a magic shell, with C₅₈ only slightly less stable and C₆₂ considerably less stable than C₆₀; (b) Dissociative decay is able to compete with radiative decay of C₆₀ ^?+ only at internal energies in excess of 37.6 eV (T_b>2300 K); (c) a Ne endohedral atom has a slightly stabilizing effect on the C₆₀ ^?+ cage whereas La is strongly stabilizing the C₈₂ ^?+ cage; (d) C₂ loss is a true evaporation in the sense of having a loose transition state with no reverse activation energy; (e) the C₂ evaporations are statistical in nature and theories such RRKM/QET and FHBT are in excellent agreement with experimental observations.     

Sulphur Contaminated Fullerenes

We report on the presence of sulphur in a commercial C₆₀/C₇₀ mixture and in C₆₀ separated by column chromatography on activated carbon. By heating under dynamic vacuum, ca. 2 wt% sulphur was eliminated from the mixture and ca. 4 wt% from C₆₀.     

Photoelectrochemical Investigation of Fullerenes

Fullerene solar cells are demonstrated. Illuminated, C₆₀ drives oxidation of redox couples in solution. a photoelectrochemical solid/liquid, rather than a solid state, junction, improves photocurrent, and a C₆₀ single crystal, and not polycrystalline film, decreases dark current, and thereby light driven charge transfer dominates.     

Zirconium Cage-Doped Fullerenes

Abstract

Some zirconium containing fullerenes were synthesized by vaporizing a zirconium-containing graphite anode with DC arc discharge technique, extracted by CS2 through low temperature extraction method, and characterized by field desorption mass spectra (FDMS). The results show that these doped fullerenes were zirconium cage-doped fullerenes.     

Fullerenes and Viruses

Abstract

It is well known that any, sometimes very small, changes in the chemical structure can lead to the dramatic changes in biological properties. Therefore it is necessary to divide into two different topics the studies of biological properties of fullerene and fullerene‐like compounds. In the enormous variety of data on the biological activity of fullerenes it is possible to select some with defined mechanism of action. This selection showed that in case of using the fullerene‐containing compositions the main mechanisms of drug action, namely unspecific, specific (ligand–receptor) interaction and membranotropic can be obtained. Therefore fullerenes as compounds with broad biological potential are very promising not only for the design of antiviral compounds, but also for the design of various types of drugs.     

Cycloaddition Reactions of Fullerenes

In the review examples of [1 + 2], [2 + 2], [3 + 2] and [4 + 2] cycloaddition reactions of fullerenes are described.     

Zirconium Cage-Doped Fullerenes

Some zirconium containing fullerenes were synthesized by vaporizing a zirconium-containing graphite anode with DC arc discharge technique, extracted by CS2 through low temperature extraction method, and characterized by field desorption mass spectra (FDMS). The results show that these doped fullerenes were zirconium cage-doped fullerenes.     

Fullerenes in Russia

Structure and main features of the Russian Research Program “Fullerenes and Atomic Clusters” are presented. Results of investigations in the framework of this Program in 1996 are briefly reviewed.     

Fullerenes in Russia

Abstract

Structure and main features of the Russian Research Program “Fullerenes and Atomic Clusters” are presented. Results of investigations in the framework of this Program in 1996 are briefly reviewed.     

Photoelectrochemical Investigation of Fullerenes

Abstract

Fullerene solar cells are demonstrated. Illuminated, C₆₀ drives oxidation of redox couples in solution. a photoelectrochemical solid/liquid, rather than a solid state, junction, improves photocurrent, and a C₆₀ single crystal, and not polycrystalline film, decreases dark current, and thereby light driven charge transfer dominates.     

A Note on Fullerenes

The existence of fullerenes with any number of hexagons different from 1 is proven in a simple way.     

Oxidation of Fullerenes by Ozone

Like typical alkenes, fullerenes can be oxidized by ozone. Epoxidation reaction takes place on C₆₀, and C₆₀On (n=l-5) are formed. Mass spectrometry and chromatography identified the stable existence of two isomers for the dioxides and three for the trioxides in the product mixtures. At lower temperatures, fragmentation occurs and results in the formation of the polar products. C₇₀ and carbon nanotubes also react with ozone but at a much slower rate.     

Gas Storage in Fullerenes

Fullerenes and in particular C₆₀ have been shown to store effectively a wide range of gases from simple monatomic rare gases to diatomics and polyatomics. A review of the research in this area conducted at ANSTO is given. The trapping of Ar, Kr, Xe, and CO₂ are discussed in detail whilst preliminary results pertaining to N₂O, CH₄, CF₄, C₂H₆ and SF₆ are also reported. A range of techniques have been used to elucidate both the structure of the new fullerene intercalated solid and the trapped gas itself. The preponderant techniques used, include infra-red absorption spectroscopy (IR), X-ray powder diffraction a (XRD), neutron powder diffraction (NRD), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA).     

Gas Storage in Fullerenes

Abstract

Fullerenes and in particular C₆₀ have been shown to store effectively a wide range of gases from simple monatomic rare gases to diatomics and polyatomics. A review of the research in this area conducted at ANSTO is given. The trapping of Ar, Kr, Xe, and CO₂ are discussed in detail whilst preliminary results pertaining to N₂O, CH₄, CF₄, C₂H₆ and SF₆ are also reported. A range of techniques have been used to elucidate both the structure of the new fullerene intercalated solid and the trapped gas itself. The preponderant techniques used, include infra-red absorption spectroscopy (IR), X-ray powder diffraction a (XRD), neutron powder diffraction (NRD), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA).     

Terrestrial and Extraterrestrial Fullerenes

This paper reviews reports of occurrences of fullerenes in circumstellar media, interstellar media, meteorites, interplanetary dust particles (IDPs), lunar rocks, hard terrestrial rocks from Shunga (Russia), Sudbury (Canada) and Mitov (Czech Republic), coal, terrestrial sediments from the Cretaceous-Tertiary-Boundary and Permian-Triassic-Boundary, fulgurite, ink sticks, dinosaur eggs, and a tree char. The occurrences are discussed in the context of known and postulated processes of fullerene formation, including the suggestion that some natural fullerenes might have formed from biological (algal) remains.     

Double-Toroid,Almost-Polyhex Fullerenes

Abstract

This study presents examples of double-toroid fullerenes comprised entirely of hexagonal faces except as required by Euler's polyhedron closure rule. Kekulé structure counts give a rough idea of stability of these structures relative to each other and to other types of fullerenes with the same carbon number (C₁₂₀). Electronic constraints demanded by the various atomic arrangements are discussed, along with possible applications.