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

开发可通过超分子化学调节的分子磁体

• 批准号: 13640575
• 负责人: ISHIDA Takayuki
• 金额: $ 2.3万
• 依托单位: The University of Electro-Communications
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640575/
• 关键词: Molecule-based magnets; metal-assembled complex; Supramolecular chemistry; Porous materials; Weak ferromagnet; ピリミジン; 有機ラジカル; 有機強磁性体; 磁気的相転移; ホストゲスト化学; 結晶工学

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.

主客体复合物形成等超分子技术已用于调整基于分子的磁性材料。我们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。第一种是由铁（II）、二氰胺阴离子和嘧啶衍生的低温磁体，其间隙中掺入了客体分子3D 框架。 T_c 范围为 3.4 K 至 5.6 K，具体取决于客体分子。它们的特征是低于 T_c 的倾斜反铁磁体。临界温度、临界场和自发磁化强度受客体夹杂物调节。第二类是六核轮状铜(II)配合物，其晶体在垂直于分子平面的方向上具有通道结构。铁磁相互作用归因于自由基取代基之间的分子间接触，通过通道内的客体包含而显着增强。水的影响尤其明显；通过去除水，磁性恢复到空的状态。该系统是通过主客体化学实现磁性能调控的罕见例子。我们还利用桥连配体作为超分子合成子制备了金属-自由基杂化磁体。开发了新型顺磁性螯合配体（4ImNNH、pzNN、pzIN、pzbisNN 和 pzbisIN）并将其应用于单核、三角形和线性多核配合物的合成。我们开发了最小桥接顺磁性配体（HIN 和 HNN）的潜在效用，并阐明选择小配体是在金属自由基固体中赋予强交换相互作用的一种有前途的策略。