Complex formation by bismuth and boron with fullerene (C₆₀): A reaction that opens up a novel route for synthesis of C₆₀–inorganic hybrid composites

A dark red colored composite of C₆₀ and (zinc, bismuth) borate glass was synthesized by solid-state reaction between C₆₀ and frits of the glass at 650–700 °C in an argon atmosphere completely free from oxygen and moisture. An unusual change in color and the absorption spectrum of the glass upon composite formation with C₆₀ indicated that the incorporated C₆₀ underwent some sort of interaction with the glass. Such fullerene molecules bonded to relatively smaller units of bismuth-boron network, were extracted out by eluting a powdered sample with toluene. The composite itself and the toluene extract there of, were then characterized by ultraviolet–visible–near-infrared, infrared, and mass spectral studies. The results showed that the bismuth ions of the bismuth-boron network were bonded with the C₆₀ cages through direct donation of their lone pair of electrons to the latter. The phenomenon of addition of boron to C₆₀ via an “oxygen bridge,” which was observed in our earlier work, was also detected in this case. Studies on the nonlinear optical properties of the composite exhibited a moderate value of third order nonlinear susceptibility χ⁽³⁾ (1.5 × 10⁻¹¹ esu) and optical limiting properties of the composite. The result showed that the material had the prospect of being used in nonlinear optical devices.