Fullerene

About: Fullerene is a research topic. Over the lifetime, 12723 publications have been published within this topic receiving 359173 citations.

Revealing the hidden atom in graphite by low-temperature atomic force microscopy

Abstract: Carbon, the backbone material of life on Earth, comes in three modifications: diamond, graphite, and fullerenes. Diamond develops tetrahedral sp3 bonds, forming a cubic crystal structure, whereas graphite and fullerenes are characterized by planar sp2 bonds. Polycrystalline graphite is the basis for many products of everyday life: pencils, lubricants, batteries, arc lamps, and brushes for electric motors. In crystalline form, highly oriented pyrolytic graphite is used as a diffracting element in monochromators for x-ray and neutron scattering and as a calibration standard for scanning tunneling microscopy (STM). The graphite surface is easily prepared as a clean atomically flat surface by cleavage. This feature is attractive and is used in many laboratories as the surface of choice for “seeing atoms.” Despite the proverbial ease of imaging graphite by STM with atomic resolution, every second atom in the hexagonal surface unit cell remains hidden, and STM images show only a single atom in the unit cell. Here we present measurements with a low-temperature atomic force microscope with pico-Newton force sensitivity that reveal the hidden surface atom.

Organic Approaches to Endohedral Metallofullerenes: Cracking Open or Zipping Up Carbon Shells?

Abstract: We have been investigating the synthesis of endohedral metallofullerenes since we successfully opened an orifice on the framework of C60 in the form of a cobalt complex having the metal sitting on top of the opening. A second approach aims at the synthesis of spherically-shaped acetylenic macrocycles, which are expected to rearrange to endohedral metal complexes of fullerenes in a controlled process analogous to the gas-phase coalescence of mono- and polycyclic polyynes during fullerene formation by the graphite evaporation method. Since the potential benefits from obtaining endohedral metal complexes of C60 are enormous, both approaches are being actively pursued in our group.

Synthesis and Properties of Endohedral C60 Encapsulating Molecular Hydrogen

Abstract: We report the details of our study to synthesize a new endohedral fullerene, H2@C60, in more than 100 mg quantities by closure of the 13-membered ring orifice of an open-cage fullerene using four-step organic reactions. The 13-membered ring orifice in a previously synthesized open-cage fullerene incorporating hydrogen in 100% yield was reduced to a 12-membered ring by extrusion of a sulfur atom at the rim of the orifice, and the ring was further reduced into an eight-membered ring by reductive coupling of two carbonyl groups also at the orifice. Final closure of the orifice was completed by a thermal reaction. Purification of H2@C60 was accomplished by recycle HPLC. A gradual downfield shift of the NMR signal for the encapsulated hydrogen observed upon reduction of the orifice size was interpreted based on the gauge-independent atomic orbital (GIAO) and the nucleus-independent chemical shift (NICS) calculations. The spectral as well as electrochemical examination of the properties of H2@C60 has shown that...

Isolation and characterisation of C70O

Abstract: C70O has been isolated in ca. 0.5% yield by HPLC separation of the soot extract obtained from a novel arc-discharge reactor for fullerene production. The reactor (DC conditions) can be operated continuously for 24 h, employs a rotating cathode and an anode consisting of continuously-fed strips cut from a carbon sheet. The 13C NMR spectrum of C70O shows that two isomers (1,2-epoxy[70]fullerene and 5,6-epoxy[70]fullerene) are present in a ratio of ca. 43∶57 and all 37 peaks corresponding to each isomer have been identified. These are the first [70]fullerene derivatives in which 5,6-addition is preferred over 1,2-addition, this preference probably deriving from the considerable strain that accompanies bridging with a single atom; the greater curvature across the 1,2-positions compared with the 5,6-positions therefore disfavours the former. Differential polarisabilities of the electrons of the 1,2- and 5,6-bonds, a factor producing a variation in reactivity order according to the attacking reagent (but not considered hitherto in the context of fullerene chemistry) may also be significant. The epoxides are unstable towards EI mass spectrometry, in contrast to epoxides possessing additional addends, and this may reflect the reduced cage strain present in the latter.