Controlled π-π stacking structure in phthalocyanine-based conductors

Axially substituted metal-phthalocyanines are utilized for constructing molecular conductors. The starting component, [M(Pc)(CN)(2)](-) (PC = phthalocyaninato), has been designed to achieve the multi-dimensional pi-pi interaction, and the conducting crystals have been obtained by the electrochemical oxidation. A variety of the pi-pi stacking structures, ranging from one- to three-dimensions, have been obtained depending on the crystal solvent for the neutral radical crystals of Co(Pc)(CN)(2). They are semiconducting with relatively high conductivity (10(-2)-10(0) S cm(-1)) at room temperature. The partially oxidized salt crystals obtained have a narrow one-dimensional metallic band. The metallic nature has been confirmed by the thermoelectric power measurements, though the conductivity is not always clearly metallic. A dramatic change in the conductivity and magnetic properties has been observed by the replacement of the central metal ion from non-magnetic Co-III to magnetic Fe-III.