Preparation, characterization and properties of C60 and C70: Spectroscopy, structure, anions, interaction with electron donors and superconductivity

Abstract

Preparation and characterization of the fullerenes, Coli and C₇₀, are described in detail, including the design of the generators fabricated locally. The characterization techniques employed are UV-visible, IR, Raman and ¹³C NMR spectroscopies, scanning as well as transmission electron microscopy and mass spectrometry. The electron energy level diagram of C₆₀ as well as the one-electron reductions of C₆₀ and C₇₀ leading to various anions are discussed. Electronic absorption spectra of C and C, are reported. Phase transitions from the plastic to the crystalline states of C₆₀ and C₇₀ are examined. Based on a ¹³C NMR study in a mixture of nematic liquid crystals, it has been demonstrated that C₆₀remains its extraordinary symmetry in solution phase as well. Interaction of C₆₀ and C₇₀ with strong electron-donor molecules has been investigated employing cyclic voltammetry. Superconductivity of K_xC₆₀has been studied by non-resonant microwave absorption; Na_xC₆₀ as well as K_xC₇₀are shown to be non-superconducting. Doping C₆₀ with iodine does not make it superconducting. Interaction of Coo with SbCl₅, and liquid Br₂gives rise to halogenated products.