Isolation and Characterization of the Higher Fullerenes from Carbon Soot

Abstract

In the first phase of the process, the higher fullerenes, mainly C 76 and C 84 , as well as the basic fullerenes C 60 and C 70 , in a smaller amount, were Soxhlet extracted with pyridine from the sample of initial carbon soot, produced in electrical arc. The extract was obtained in increased, high yield of 16.4%, due to application of the original procedure. The solubility of fullerenes in this solvent was determined. Chromatographic separation of fullerenes from pyridine extract was performed by continual elution, in one phase of the process, under atmospheric pressure, with original, defined gradient of solvents, from pure hexane to pure toluene, on active Al 2 O 3 column, by a new, improved method. Identifications of fullerenes in the obtained chromatographically purified fractions and pyridine extract of the initial soot were performed using determined IR and UV/VIS techniques that have not been presented previously for the higher fullerenes.

Recent Advances in IR and UV/VIS Spectroscopic Characterization of the C76 and C84 Isomers of D2 Symmetry

“…It should be mentioned that the region from 200 to 300 nm has not been previously presented for C 84 and its isomers under any experimental conditions. Complete appearance of their electronic absorption spectra and all the observed absorption bands [22][23][24][25][26][27][28] correlates well with the previous semiempirical QCFF/PI, TB, and DFT theoretical predictions of the molecular electronic structure and the optical absorption of these molecules that behave as electron deficient arenes [48][49][50][51]. Their overall absorption also correlates well with the experimentally obtained photoemission spectra (PES) of C 76 and C 84 [49][50][51].…”

“…450 to 1650 cm −1 . The general pattern of the obtained spectra and all the observed absorption bands of the chromatographically isolated samples of the stable C 76 and C 84 isomers with D 2 symmetry from the several different original, advanced separation processes [22][23][24][25][26][27][28] are in excellent agreement with the semiempirical, ab initio, and density functional theory (DFT) theoretical calculations for these molecules [5-12, 29, 30] over the mentioned relevant region. It should be noted that some low frequencies can exist below the observational limit of 400 cm −1 .…”

“…In the second phase, C 60 , C 70 , and the higher fullerenes C 76 and C 84 from the obtained soot extracts were chromatographically separated on the activated Al 2 O 3 columns by the new and improved methods [22][23][24][25][26][27][28]. The elution was performed continuously with the several different original, defined gradients of solvents: from pure hexane or 5% toluene in hexane to pure toluene, at ambient conditions.…”

“…The entire material and energy expense and the time spent on the purification processes were decreased. The environment pollution was also decreased, using smaller amounts of less toxic solvents [22][23][24][25][26][27][28].…”

“…Characterization of the chromatographically purified fullerene fractions, as well as of the obtained fullerenes soot extracts, was performed using determined techniques of IR and UV/VIS spectroscopy that have not been presented previously for the higher fullerenes [22][23][24][25][26][27][28][36][37][38].…”