Development of Molecule-Based Magnets Tunable by Means of Supramolecular Chemistry

超分子技术，如主客体络合物的形成，已经被用来调节分子基磁性材料。我们已经开发了两种纳米多孔磁性材料，其磁性通过包含小的抗磁性分子而改变。第一种是来自铁(II)、二氰胺阴离子和嘧啶的低温磁体，它们的客体分子被引入到三维骨架的间隙中。根据客体分子的不同，T_c在3.4~5.6K之间。在T_c以下为斜面反铁磁体。临界温度、临界场和自发磁化强度受客体包裹体的调制。二是六核轮状铜(II)络合物，其晶体具有垂直于分子平面方向的沟道结构。由于自由基间的分子间相互作用，通道内的客体包裹体显著增强了铁磁性相互作用。水的影响尤其明显；通过去除水，磁性恢复到空的磁性。该体系是通过主客体化学手段实现磁性调控的罕见例子。我们还利用桥联配体作为超分子合成子制备了金属-自由基杂化磁体。开发了新型顺磁性配体(4ImNNH、pzNN、pzIN、pzbisNN和pzBisin)，并将其应用于单核、三角形和线形多核配合物的合成。我们开发了最小的桥联顺磁配体(HIN和HNN)的潜在用途，并阐明了选择小的配体是在金属-自由基固体中赋予强交换作用的一种有前途的策略。

Supramolecular techniques such as host-guest complex formation have been used to tune molecule-based magnetic materials. We have developed two nano-porous magnetic materials, whose magnetic properties were changed by inclusion of small diamagnetic molecules.The first are low-temperature magnets derived from iron(II), dicyanamide anion, and pyrimidine, which have guest molecules incorporated in the clearance of the 3-D framework. The T_c ranges from 3.4 K to 5.6 K, depending on the guest molecules. They are characterized as canted antiferromagnets below T_c. The critical temperature, critical field, and spontaneous magnetization are Modulated by the guest inclusion.The second are hexanuclear wheel-shaped copper(II) complexes, whose crystals have a channel structure in a direction perpendicular to the molecular plane. The ferromagnetic interaction, which is ascribed to intermolecular contacts between the radical substituents, was remarkably enhanced by guest inclusion within a channel. The effect of water is especially noticeable ; the magnetic properties returned to the empty one by removal of water. This system is a rare example of realizing the regulation of magnetic properties by means of host-guest chemistry.We also prepared metal-radical hybrid magnets using bridging ligands as supramolecular synthons. Novel paramagnetic chelating ligands (4ImNNH, pzNN, pzIN, pzbisNN, and pzbisIN) were developed and applied to the synthesis of mononuclear, triangular, and linear polynuclear complexes. We have exploited potential utility of the smallest bridging paramagnetic ligands (HIN and HNN) and clarified that the choice of small ligands was a promising strategy to bestow strong exchange interaction in metal-radical solids.