Electronic structure and spectroscopy of C60 nitroaryl radical adducts

Abstract

In this study, density functional theory (DFT) calculations were applied to study electronic structure and spectroscopy of C60 nitroaryl radical adducts with 2-nitrophenyl, 4-nitrophenyl, 2,4-dinitrophenyl and up to six 2,4,6-trinitrophenyl substituents. The structural parameters for optimized geometries were measured, and polarity of molecules was compared to nitrobenzene derivatives. The atomic charges and charge distribution map of these compounds were calculated based on electrostatic potential (ESP) and natural population analysis (NPA). The distribution of unpaired electron in opened shell molecules was visualized by spin density profiles. The calculated thermochemical constants for reactions of nitroaryl radicals with C60 were reported. The wave function analysis was performed to study molecular orbital (MO) and density of states (DOS) diagrams. The aromaticity index of molecules was estimated by nucleus-independent chemical shift (NICS) method. The infrared (IR) and carbon-13 nuclear magnetic resonance (13C NMR) spectra of these compounds were also investigated. It was found that addition of nitroaryl radicals to C60 is exothermic and occurs with decreasing entropy and Gibbs free energy. These compounds exhibit higher aromatic character and smaller band gap compared to C60.