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

Hindawi Journal of Nanomaterials Volume 2017, Article ID 4360746, 10 pages https://doi.org/10.1155/2017/4360746 Research Article The IR Spectra, Molar Absorptivity, and Integrated Molar Absorptivity of the C76-D2 and C84-D2:22 Isomers Tamara JovanoviT,1 Yuro Koruga,1 and Branimir JovanIiTeviT2 1 Department of Biomedical Engineering, Faculty of Mechanical Engineering, University of Belgrade, Kraljice Marije 16, 11120 Belgrade, Serbia 2 Department of Applied Chemistry, Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade, Serbia Correspondence should be addressed to Tamara Jovanović; Received 4 February 2017; Revised 20 February 2017; Accepted 22 February 2017; Published 5 March 2017 Academic Editor: Xuping Sun Copyright © 2017 Tamara Jovanović et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The FT-IR spectra of the stable C76 and C84 isomers of D2 symmetry, isolated by the new, advanced extraction and chromatographic methods and processes, were recorded by the KBr technique, over the relevant region from 400 to 2000 cm−1 , at room temperature. All the observed infrared bands are in excellent agreement with the semiempirical QCFF/PI, DFT, and TB potential calculations for these fullerenes, which is presented in this article, as the evidence of their validity. The molar absorptivity 𝜀 and the integrated molar absorptivity 𝜓 of their IR absorption bands were determined and reported together with the relative intensities. Excellent agreement is found between the relative intensities of the main and characteristic absorption maxima calculated from 𝜀𝜆 and from the 𝜓𝜆 values in adequate integration ranges. These results are significant for the identification and quantitative determination of the C76 -D2 and C84 -D2 :22 fullerenes, either in natural resources on Earth and in space or in artificially synthesized and biomaterials, electronic, optical, and biomedical devices, sensors, polymers, optical limiters, solar cells, organic field effect transistors, special lenses, diagnostic and therapeutic agents, pharmaceutical substances in biomedical engineering, and so forth. 1. Introduction Fullerenes C60 and C70 were detected in a series of astrophysical objects and space environments [1–6], such as certain planetary [7, 8] and protoplanetary [9] nebulae, postasymptotic giant branch stars, young stellar objects [10], reflection nebulae [11], certain R-Coronae Borealis stars, and carbon rich stars [12–16], as well as in some resources on Earth [17, 18]. The identification and quantitative assessment of these molecules, both in natural and in artificially synthesized materials, were made possible by the measurement of their IR spectra, the dependence of these spectra on temperature, the molar absorptivity, and integrated molar absorptivity of their absorption bands [2–26]. It is expected that also higher fullerenes can be found in space, besides C60 and C70 . Calculations [27] suggest that, on a per carbon atom basis [1], higher fullerenes are thermodynamically even more stable than C60 , C70 [28], and from the hydrogenated derivatives fulleranes [17, 18, 29–31]. Their formation through coalescence of smaller fullerenes [32] and by laser ablation of carbon [17–19, 33, 34] also leads to the conclusion about their possible presence in nature. For the qualitative detection of C76 and C84 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, 35–42] in the infrared spectroscopy of C76 and C84 , 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 C76 -D2 isomer [43–45] and the most abundant, stable isomer of the higher fullerene C84 with D2 symmetry, C84 -D2 :22 [46–54], were isolated from carbon soot, by new and advanced chromatographic methods and processes [35–42], in comparison to previous methods for the separation of higher fullerenes under pressure [55–63]. Their IR (KBr) spectra were recorded over the entire relevant region, from 400 to 2000 cm−1 in transparence mode [35–42], and in the absorption mode in this article. 2 A comparison of the experimentally observed vibrational frequencies in the IR absorption spectra of the isolated C76 -D2 and C84 -D2 :22 samples [35, 38] with the semiempirical QCFF/PI, DFT, as well as TB potential theoretical calculations for these fullerenes [44, 45, 48–50], is presented in this article, indicating their validity. In this work also, the molar extinction coefficients and the integrated molar extinction coefficients of their main and characteristic IR absorption bands were determined. These data are important for the qualitative and quantitative determination of the C76 -D2 and C84 -D2 :22 isomers, either in natural resources on Earth and in space or in artificially synthesized materials, electronic and optical devices, diagnostic and therapeutic agents for the applications in biomedical engineering, and so forth. 2. Experimental Methods In the first phase of this research, C60 , C70 [24–26], and the higher fullerenes, mainly C76 and C84 [35–42], 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. Solvents used were n-heptane, toluene, chlorobenzene, p-xylene, a mixture of o/m/p-xylene, and pyridine, as well as the successive use of toluene and chlorobenzene and p-xylene and pyridine. The yields, as well as the compositions of all the extracts, were determined by spectroscopic and chromatographic methods. The procedures for increases of fullerenes yields, as well as for additional selective extraction of higher order fullerenes, were found [24–26, 35–42]. In the second phase, C60 , C70 , and the higher fullerenes C76 and C84 (the only stable C60 -Ih, C70 -D5h , and C76 -D2 isomers of the first three mentioned fullerenes and the most abundant, stable C84 isomer of D2 symmetry) were chromatographically separated from the obtained soot extracts on the activated Al2 O3 columns, by new and advanced methods [35– 42]. The main difference and advancement of these methods [35–42], in comparison to previous methods under pressure [55–63], is the isolation of the purified stable isomers of the higher fullerenes C76 and C84 (the C76 -D2 and C84 -D2 :22 isomers), successively after the basic fullerenes, in one phase of each of the processes, under atmospheric pressure and sm (...truncated)