Design of Novel Superconductors and Magnetic Conductors Based on Stepwise π-Stacking Structures

利用具有轴向CN配体的酞菁（Pc）配合物开发了基于原设计的逐步堆叠的新型导体。当中心金属离子为非磁性Co^<III>时，可得到正常导体；当中心金属离子为磁性Fe^<III>时，可得到磁性导体。电化学氧化[Co^<III>(Pc)(CN)_2]^-生成中性自由基，使Pc配体变成开壳结构。与溶剂分子共晶时，由于有效的π-π堆积，提高了晶体的导电性。根据溶剂种类的不同，得到了不同的堆积结构。由于电子相关效应，中性自由基晶体是半导体，而与阴离子（部分氧化盐）结晶则是金属导体。它们的形成取决于阳离子的种类，并且有6种部分氧化盐具有不同的π-π堆叠。其中具有双二维片状结构的晶体在低温高压下仍能保持金属性质。电化学氧化[Co^<III>(Pc)(CN)_2]^-得到与Co盐的同晶晶体。在一维体系中，对Co和Fe盐的物理性质进行了详细的研究。根据热电功率和光反射率的测量，发现它们的电子结构是相同的。另一方面，发现Co盐的电导率差异很大，Co盐的电阻率几乎是恒定的，而Fe盐在低温下表现出绝缘行为。这是由于在Pc环中心存在周期性排列的磁矩。作为一个重要的结果，我们发现外加磁场使电阻率降低。这种一维系统表现出“巨大的负磁阻”是不寻常的。少

Phthalocyanine (Pc) complexes with axial CN ligands were utilized for development of novel conductors based on the originally devised stepwise stacking. When the central metal ion is nonmagnetic Co^<III> normal conductors can be obtained, while when it is magnetic Fe^<III> magnetic conductors can be obtained.Electrochemical oxidation of [Co^<III>(Pc)(CN)_2]^- yields the neutral radical species in which the Pc ligand becomes open-shell structure. The crystal constructed solely with this species was not highly conducting while co-crystallization with solvent molecules improved the conductivity due to the efficient π-π stacking. Various stacking structures depending on the solvent species have been obtained. The neutral radical crystals are semiconductors due to the electron correlation effect, while crystallization with the anion (partially oxidized salt) gage metallic conductors. Their formation depends on the cationic species, and six partially oxidized salts with various π-π stacking … More structures have been obtained. Among them the crystal with double two-dimensional sheeto structure has been found to maintain metallic character at low temperatures under high pressure.Electrochemical oxidation of [Co^<III>(Pc)(CN)_2]^- gave isomorphous crystals with the Co salts. For the one-dimensional system, the physical properties of the Co and Fe salts were investigated in detail. Electronic structure was found to be identical based on the thermoelectric power and optical reflectance measurements. On the other hand, the electrical conductivity was found to be dramatically different from each other , the resistivity is almost constant for the Co salt, while it shows insulating behavior at low temperature for the Fe salt. This is due to the existence of periodically arranged magnetic moments at the center of the Pc rings. As an important consequence, we have found that the resistivity decreases by applying external magnetic field. It is unusual that such a one-dimensional system shows "giant negative magnetoresistance". Less