Manufactured nanoparticles: An overview of their chemistry, interactions and potential environmental implications

Electrochemistry of Fullerenes and Their Derivatives

Encapsulating atoms or molecules inside fullerene cages could give rise to a myriad of novel molecules and materials. The existence of such species is now strongly supported by a growing body of experimental evidence. Fullerene& ndash;metal complexes generally thought to be endohedral are being produced and purified in milligram quantities, and their structure and properties are beginning to be explored

Atoms in carbon cages: the structure and properties of endohedral fullerenes

Initially envisaged as rather unreactive, aromatic-like molecules, the fullerenes instead undergo a wide variety of reactions characteristic of alkenes. The many derivatives of C60, and the few of C70, that have now been reported offer new directions for organic chemistry.

The Chemistry of Fullerenes

Life on earth is based on compounds that have carbon frames and backbones. Today, chemists have added to the world of biomolecules and biopolymers approximately 107 different synthetic molecules and polymers, the structures of which also depend on the formation of strong, stable carbon–carbon bonds. Although the stability of carbon–carbon bonds has been recognized for more than a century, the two natural modifications graphite and diamond were, until recently, the only allotropic forms of carbon on earth that were available in macroscopic quantities and were structurally well characterized. With the synthesis of macroscopic quantities of buckminsterfullerene (C60) and the higher fullerenes (C70, C76, C78, etc.) and the exploration of the fascinating properties of these all-carbon spheres, this situation has completely changed. In the coming decades, the design, preparation, and study of novel molecular and polymeric allotropic forms of carbon will be a central topic in chemistry. Research in this area will dramatically advance the fundamental knowledge on carbon-based matter and, as already illustrated by the ongoing work on C60, generate unprecedented technological perspectives. This review surveys synthetic organic-chemical approaches toward the preparation and study of all-carbon molecules and polymers that differ from the familiar networks of graphite and diamond as well as from the fullerenes. We will also discuss the ongoing research on fullerenes with a particular focus on the synthetic approaches to these all-carbon spheres and their transition metal complexes.

Synthetic approaches toward molecular and polymeric carbon allotropes

FOLLOWING the development of a method for bulk synthesis of C60 and other fullerenes1, the isolation of higher fullerenes ranging from C76 to C96 has been achieved using chromatographic techniques2–5. Whereas C60 and C70 have unique, high-symmetry structures6, theoretical calculations for fullerenes larger than C76 have suggested that each may exist in at least two isomeric forms7. For C84, 24 isomers have been postulated7, and for C96calculations have yielded 196 distinct isomers8. Diederich et al.9 have used liquid chromatography and 13C NMR to identify two isomers of C78, but previous experimental studies of other higher fullerenes2 have produced ambiguous results. Here we use 13C NMR to determine the structures of some principal isomers of C78, C82 and C84. We find a third isomer of C78, which was not reported in ref. 9. Characterization of the structures of these larger fullerenes should provide new understanding of the factors determining the stability of hollow carbon clusters.

NMR characterization of isomers of C 78 , C 82 and C 84 fullerenes

Isolation and identification of fullerene family: C76, C78, C82, C84, C90 and C96

Isolation and characterization of the metallofullerene LaC82

New kinds of fullerenes were separated by HPLC with benzene from carbon soot. At least four fractions were well separated. Mass analysis confirmed the separation of C60, C70, C84 and the mixture of C76 and C78. Absorption spectra of C76, C78, and C84 were measured for the first time.

N. Nakahara

Papers

NMR characterization of isomers of C 78 , C 82 and C 84 fullerenes

Isolation and identification of fullerene family: C76, C78, C82, C84, C90 and C96

Isolation and characterization of the metallofullerene LaC82

Separation, Detection, and UV/Visible Absorption Spectra of Fullerenes; C76, C78, and C84

Higher fullerenes; separation and molecular structures