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

Abstract

The stable isomers of the higher fullerenes C 76 and C 84 with D 2 symmetry as well as the basic fullerenes C 60 and C 70 were isolated from carbon soot and characterized by the new and advanced methods, techniques, and processes. The validity of several semiempirical, ab initio, and DFT theoretical calculations in predicting the general pattern of IR absorption and the vibrational frequencies, as well as the molecular electronic structure of the C 76 and C 84 isomers of D 2 symmetry, is confirmed, based on recent experimental results. An excellent correlation was found between the previously reported theoretical data and the recently obtained experimental results for these molecules over the relevant spectral range for the identification of fullerenes. These results indicate that there are no errors in the calculations in the significant spectral regions, the assumptions that were based on previous comparisons with partial experimental results. Isolated fullerenes are important for their applications in electronic and optical devices, solar cells, optical limiting, sensors, polymers, nanophotonic materials, diagnostic and therapeutic agents, health and environment protection, and so forth.

The IR Spectra, Molar Absorptivity, and Integrated Molar Absorptivity of the C76-D2and C84-D2:22 Isomers

“…A comparison of the experimentally observed vibrational frequencies in the IR absorption spectra of the isolated C 76 -D 2 and C 84 -D 2 :22 samples [35,38] with the semiempirical QCFF/PI, DFT, as well as TB potential theoretical calculations for these fullerenes [44,45,[48][49][50], is presented in this article, indicating their validity.…”

“…In the first phase of this research, C 60 , C 70 [24][25][26], and the higher fullerenes, mainly C 76 and C 84 [35][36][37][38][39][40][41][42], were Soxhlet-extracted with a series of different and previously unapplied solvents or combinations of solvents from the samples of carbon soot, produced by electric arc (MER Corporation, Tucson, USA). The extraction procedures were performed until the complete disappearance of color in a Soxhlet extraction thimble.…”

“…For the qualitative detection of C 76 and C 84 fullerenes, the knowledge of the infrared band position and band widths, as well as the evolution of these parameters with temperature, is necessary. This need was fulfilled, for instance, by the previous works [1,[35][36][37][38][39][40][41][42] in the infrared spectroscopy of C 76 and C 84 , whereas quantitative assessment of these fullerenes requires knowledge about intensities of their IR absorption bands, which is provided in the current work.…”

“…In the first phase of this research, the only stable C 76 -D 2 isomer [43][44][45] and the most abundant, stable isomer of the higher fullerene C 84 with D 2 symmetry, C 84 -D 2 :22 [46][47][48][49][50][51][52][53][54], were isolated from carbon soot, by new and advanced chromatographic methods and processes [35][36][37][38][39][40][41][42], in comparison to previous methods for the separation of higher fullerenes under pressure [55][56][57][58][59][60][61][62][63]. Their IR (KBr) spectra were recorded over the entire relevant region, from 400 to 2000 cm −1 in transparence mode [35][36][37][38][39][40][41][42], and in the absorption mode in this article.…”

Энергетический Спектр И Оптическое Поглощение Углеродных Наносистем На Примере Изомеров N 11 И 22 Фуллерена С-=sub=-84-=/Sub=-

“…Исследование энергетического спектра оптического поглощения изомера № 22 фуллерена С 84 нами было проведено аналогично, исследованию изомера № 11, рассматриваемого фуллерена. Этот изомер является наиболее распространенным среди всех стабильных изомеров фуллерена С 84 [40]. Он относится к группе симметрии D 2 .…”