Advancement of the Process for Extraction, Chromatography and Characterization of Fullerenes

Abstract

In the first phase of this work, the basic C 60 and C 70 as well as the higher fullerenes, mainly C 76 and C 84 , were Soxhlet extracted with p-xylene and n-heptane from the samples of carbon soot, produced in electrical arc, yielding 5.9% and 0.7% of the extract, respectively. The remaining, p-xylene insoluble soot was then extracted with pyridine, by original advanced method, increasing the entire extract yield for an additional 5.9% to 11.8%. The procedures for increases of the basic and higher fullerenes yields, as well as for additional, selective extraction of the higher fullerenes were found. Chromatographic separation of the basic and the higher C 76 and C 84 fullerenes from p-xylene extract was performed by continual elution, in one phase of the process, under atmospheric pressure, with original, defined, gradient of solvents from 5% toluene in hexane to pure 100% toluene, on active Al 2 O 3 column, by a new, improved method. Identifications of the basic and the higher fullerenes in chromatographically purified fractions, as well as in the obtained extracts, were performed using determined techniques of IR and UV/VIS spectroscopy that have not been presented previously for the higher fullerenes.

Isolation and Characterization of the Higher Fullerenes from Carbon Soot

“…IR and UV/VIS absorption maxima of the higher fullerenes C 76 and C 84 are in good agreement with the spectra of C 76 and C 84 samples that we obtained in several other processes (18).…”

“…The absorptions at 1076, 1127 and a bend at 1184 cm −1 moved toward lower frequency correspond to C 84 . Complete absorption in this significant spectrum indicates the dominant presence of the higher fullerene C 84 in the sixth fraction of pyridine extract (18,21,22).…”

“…All absorption bends in this significant spectrum correspond to carbon cluster C 84 , as evidence of its dominant presence in the sixth fraction of pyridine extract (15,18).…”

“…In the visible part, a bend at 405 nm and absorption prolonged to 900 nm correspond to C 76 . Relative intensities and locations of absorption maxima indicate the dominant presence of the higher fullerene C 76 in the fourth fraction of pyridine extract (15,(18)(19)(20).…”

“…The isolated higher fullerenes are significant for further investigations of their physical, chemical and spectroscopic properties, as well as for the numerous possible nanotechnological applications in, for example, electronic and optical devices, solar cells, optical, chemical or acoustic sensors, catalysts, synthesis of diamonds, storage of hydrogen, batteries, superconductors, diagnostic or therapeutic agents, transport of metal atoms or biologically active molecules in vivo (1)(2)(3)(4)(5)(6)(7)(8)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32).…”