Novel phthalocyanine-based conductors: tunable pi-pi stacking structure through the steric and chemical interactions of axial ligands

Various electrically conducting neutral radical and partially oxidized salt crystals can be obtained by electrochemical oxidation of dicyano(phthalocy aninato)cobalt(III) anion, [Co(Pc)(CN)(2)](-). In most of the neutral radic al crystals, crystal solvents are incorporated in the lattice, and the dime nsionality of the pi-pi interaction can be tuned by selecting the solvent. When the neutral radical crystallizes without crystal solvents, the pi-pi i nteraction becomes much less efficient. The electrical conductivity of the solvent-inclusive crystals is high, 10(-2)-1 S cm(-1) at room temperature, while that of the solvent-free crystal is much lower, similar to 10(-4) S c m(-1). The partially oxidized salt crystals have been obtained when the cat ion is K+, TPP+ or (PXX2)(+) (TPP+=tetraphenylphosphonium; PXX=perixantheno xanthene). In these crystals the Pc pi -ligand is commonly oxidized by 0.5e , and they show high conductivity up to 2 x 10(2) S cm(-1) at room temperat ure. The dimensionality of the pi-pi interactions is varied by the shape of the cationic part. Copyright (C) 2001 John Wiley & Sons, Ltd.