有机自由基桥联高自旋金属簇合物构筑新型多孔磁体的研究

Porous magnets have become the hot research point in the field of molecular-based materials, owing to their potential applications as magnetic sensors, low-density magnets, magnetic separation media, etc. The project will carried out studies as follows, focusing on seeking new types of porous magnets with high Tc temperatures and permanent porosities.Porous magnets with novel structures will be designed and synthesized by the self-assembly strategies, using metal clusters with high spins as secondary building units and paramagnetic organic radicals as bridge ligands.Porosities and magnetic properties will be characterized through structural, spectroscopic, and physical and chemical properties measurements. The influences of the topologies of porous magnets, the types and geometric configurations of clusters and organic radicals, and the inducements of guest molecules on magnetic properties of porous magnets will be discussed in detail. Furthermore, the selective soprtion properties for paramagnetic molecules or ions will be also carried out.The density functional theory will be employed to study the magnetic exchange couplings and mechanism, and to explore the relationship between structural characteristics and magnetic properties. Thus, the incompatibility between the increasing porosities and diminishing magnetic coupling interactions can be resolved by the introduction of paramagnetic organic radicals, while the porous magnets comprising metal clusters with high spins will increase the Tc values. The project will provide important experimental evidences and theoretical guidance for the development and application of new types of porous magnets.

多孔磁体可潜在应用于磁性传感器、低密度磁体或磁分离介质等，是当前分子基材料领域的前沿热点。本项目以寻找兼具高Tc温度和牢固多孔性的多孔磁体为目标，开展以下研究：（1）以高自旋金属簇合物为次级构筑单元，以顺磁性有机自由基为桥联配体，通过自组装设计合成结构新颖的多孔磁体；（2）结合结构测定、谱学表征和物理化学性能测试系统研究多孔磁体的磁性和多孔性，探讨多孔磁体的拓扑结构、金属簇合物和有机自由基的种类及几何构型、客体分子的诱导等对多孔磁体磁性的影响，并开展多孔磁体选择性吸附分离顺磁性分子或离子的研究；（3）利用密度泛函理论计算磁耦合常数，研究磁交换作用机理，揭示多孔磁体的结构与磁性之间的相关性规律。顺磁性有机自由基作为桥联配体可望解决孔径增大和三维磁耦合减弱的矛盾，而高自旋金属簇合物作为次级构筑单元有利于提高多孔磁体的Tc温度。本项目为新型多孔磁体的开发及应用提供重要的实验依据和理论指导。

本项目以设计合成新型分子基多孔磁体为目的，主要开展了以下研究工作：选用特定的有机配体为构筑基元，将其与氰基合金属盐和/或过渡（或镧系）金属离子及其簇合物在不同的溶剂体系中组装反应，成功制备了95个结构新颖的镧系金属、羧酸基过渡金属和氰基双金属化合物，其中包括25个零维簇合物、11个一维链、24个二维层和35个三维多孔结构。采用现代测试手段对这些化合物的物相组成、结构特征和热稳定性等进行了系统的表征与研究，重点考察了部分化合物的多孔性和磁学性质。研究发现，化合物29为变磁体，另外在化合物14、16、51、58、59和61中观察到典型的慢磁豫现象，化合物61为单离子磁体。在此基础上，探讨了构筑新型多孔磁体的有效方法，揭示了化合物的结构特征与其多孔性及磁性之间的相关性规律。本项目的实施为新型多孔磁体的开发和研究提供了重要的实验依据和理论指导，同时也为多孔磁体在功能器件领域的商业应用打下了坚实基础。