Synthesis and spectral characterization of water-soluble derivatives of C₇₀ and high-order fullerene mixture (C₇₆, C₇₈ and C₈₄) achieved by chemically induced air oxidation

The direct air oxidation of chemically reduced high-order fullerene carbon structures affords quantitative yields of oxygenated, pH-sensitive water-soluble derivatives of C₇₀ and a high-order fullerene mixture (C₇₆, C₇₈ and C₈₄). Reactant fullerenes have been investigated spectroscopically by solution and cross polarization - magic angle spinning (CP-MAS) solid-state ¹³C nuclear magnetic resonance (NMR), vibrational Fourier transformed -infrared (FT-IR) and Raman spectroscopy, ultraviolet - visible (UV-VIS) and solid-state near infrared spectroscopy (NIR), X-ray powder diffraction (XRPD), scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM-EDX) and matrix assisted laser desorption ionization - time of flight mass spectrometry (MALDI-TOF MS) techniques. Hydroxylic, ketonic and carboxylic oxygen moieties covalently attached to cluster carbon cages, after the synthesis of such carbon structures. The high reactivity displayed by these carbon clusters indicates that both the molecular convexity and the structural strain are important parameters that easily favour the oxidation of chemically reduced π-delocalised carbon frameworks.