Recent Advances in Chromatographic Separation and Spectroscopic Characterization of the Higher Fullerenes C₇₆ and C₈₄

Abstract

The basic and the higher fullerenes were chromatographically isolated from the obtained series of carbon soot extracts, in increased yields, by the new, advanced methods, on Al2O3 columns. The elution was performed continuously, in one phase of each process, at ambient conditions, with the several different original hexane-toluene gradients. Various separation systems were used previously. The unique and the main, dominant absorption maxima of the purified higher fullerenes were registered in the spectral regions where they intensively absorb, applying the IR and UV/VIS techniques. All the observed absorption bands are in excellent agreement with theoretical calculations, indicating the achieved advancement in chromatographic separation and spectroscopic characterization. The isolated fullerenes are important for investigation of their remarkable optical and electronic properties, as well as for the numerous possible applications in chemistry, physics, biomedicine, diagnostic and therapeutic agents, sensors, polymers, nanophotonic materials, special lenses, optical limiting, organic field effect transistors, solar cells etc.

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].…”