Structure and Vibrational Spectroscopy of C82 Fullerenol Valent Isomers: An Experimental and Theoretical Joint Study

Abstract

Gd@C82OxHy endohedral complexes for advanced biomedical applications (computer tomography, cancer treatment, etc.) were synthesized using high-frequency arc plasma discharge through a mixture of graphite and Gd2O3 oxide. The Gd@C82 endohedral complex was isolated by high-efficiency liquid chromatography and consequently oxidized with the formation of a family of Gd endohedral fullerenols with gross formula Gd@C82O8(OH)20. Fourier-transformed infrared (FTIR) spectroscopy was used to study the structure and spectroscopic properties of the complexes in combination with the DFTB3 electronic structure calculations and infrared spectra simulations. It was shown that the main IR spectral features are formed by a fullerenole C82 cage that allows one to consider the force constants at the DFTB3 level of theory without consideration of gadolinium endohedral ions inside the carbon cage. Based on the comparison of experimental FTIR and theoretical DFTB3 IR spectra, it was found that oxidation of the C82 cage causes the formation of Gd@C82O28H20, with a breakdown of the integrity of the parent C82 cage with the formation of pores between neighboring carbonyl and carboxyl groups. The Gd@C82O6(OOH)2(OH)18 endohedral complex with epoxy, carbonyl and carboxyl groups was considered the most reliable fullerenole structural model.

Effects of Endohedral Gd-Containing Fullerenols with a Different Number of Oxygen Substituents on Bacterial Bioluminescence

“…Further, hydrogen was added to the oxygen atoms, resulting in different functional groups (hydroxyl, carbonyl, and carboxyl). For this compound, the band in the FTIR spectrum at around 1700 cm −1 indicated a carboxyl group [83], and thus, we built two carboxyl groups symmetrically on the opposite sides of the carbon cage. As a result, there were 30 hydroxyl (-OH), 8 epoxy (C-O-C), and 2 carboxyl (-COOH) functional groups in the C 82 O 42 H 32 fullerenol model (Figure 3c).…”

“…Two valence isomers were constructed for fullerenol C 82 O 20 H 14 and one isomer for fullerenol C 82 O 42 H 32 . The atomic structures of the obtained models were optimized using the DFTB [83,96,97] with 3ob-3-1 parameters [98]. For the equilibrium geometries, the IR spectra (Figure 4b,d,e) were calculated using the GAMESS program [99].…”