Establishment of Structure-Conductivity Relationship for Tris(2,2′-bipyridine) Ruthenium Ionic C₆₀ Salts

Three ionic C60 salts with [Ru(bpy)3]m+ (bpy = 2,2′-bipyridine) as cations were synthesized. The UV−vis−NIR spectra, XPS spectra, and elemental analysis have demonstrated their compositions: [Ru(bpy)3]2(C60) (1), [Ru(bpy)3](C60) (2), and [Ru(bpy)3](C60)2 (3). Single crystals of polycrystalline compounds 1 and 2 were obtained as solvates. At room temperature, all three salts are semiconducting with the highest four-probe conductivity observed for compound 1 at ∼10 S m−1. The electronic conduction mechanisms can be described appropriately by an electron hopping model in this immobilized polyvalent redox system.