Electronic functionality of the slipped-stacked assembly structure of the macrocyclic π-ligand complexes

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Electrical conductors composed of axially substituted macrocyclic π-ligand metal complexes have following features: I. various π-π stacking networks, II. variation of the electrical properties by the stacking structure, III. π-d interaction and response to the external magnetic field (negative magnetoresistance) on the introduction of magnetic moments. We examined the chemical modification, electron correlation, and dimensionality of the π-n interaction of the phthalocyanine system, and obtained following results.We newly developed a single-step axial ligand exchange method, and a series of the isomorphous one-dimensional conductors were obtained. For the non-magnetic Co system, the axial ligand exchange was found to affect the π-π interaction, while, for the magnetic Fe system, the exchange was found to modify the π-d interaction by shifting the energy of the d-orbitals accommodating the unpaired electron. This is the first example of the tunable π-d system.Though the electronic struc … More ture of the one-dimensional conductors is metallic, the temperature dependence of the charge transport is thermally activated. This was found to be due to the charge-disproportionation from the NQR measurements. The current-voltage characteristics indicated non-linear behavior, suggesting melting of the charge- disproportionation by high electric fields. For the Fe system, more pronounced non-linearity was observed. Therefore, the giant negative magnetoresistance in this system is a reduction of the resistance accompanied by the change from the charge-disproportionation state to spin-aligned state by applying magnetic fields.We also succeeded in obtaining a two-dimensional partially oxidized salt by exchanging the cationic component. The metallic state at low temperature was observed for the Co system under pressure, while abrupt increase of resistivity was observed for the Fe system at 20 K. The π-d interaction in the two-dimensional system is considered to be different from that in the one-dimensional system in which magnetic order is absent. Less