Selective solution-phase generation and oxidation reaction of C60n- (n = 1,2) and formation of an aqueous colloidal solution of C60

Abstract

The facile chemical methods for the selective solution-phase generation of C₆₀^n- (n = 1,2) and the preparation of an aqueous colloidal solution of C₆₀ are reported. When C₆₀ was treated with Al–Ni alloy or tin (or zinc powder or sodium hydrosulfite) in aqueous NaOH–THF or in aqueous NaOH–DMSO or DMF, C₆₀^- or C₆₀^2- was produced selectively with no need for control of stoichiometry. The reaction products were characterized by ESI–MS, VIS–NIR, EPR and ¹³C NMR spectroscopies. It was found that C₆₀^n- (n = 1,2) was inert to water, but very sensitive to oxygen. The oxidation reaction of C₆₀^2- with oxygen follows the sequence: C₆₀^2-→C₆₀^1- →C₆₀, which is monitored by NIR absorption spectroscopy. When C₆₀^n- (n = 1,2) is oxidized in aqueous solution the C₆₀ sol is formed, but in dry organic solvent black C₆₀ powder is deposited. It was proved that the sol was composed of C₆₀ by UV, FTIR and ESIMS. Transmission electron microscope analysis showed that the colloidal particles, ca. 10 nm in diameter, were non-crystalline and quite homogeneous.