稀土分子纳米磁体的设计合成及性质研究是当前分子磁性的热点研究领域。本论文利 用酰腙席夫碱配体和稀土镝离子构筑了 36 个具有新颖结构的配合物，并深入研究了它们 的磁学性质，构筑了系列稀土分子纳米磁体，研究成果如下： 1、合成了系列新颖的氮氧吡啶酰腙席夫碱配体。并利用其与镝离子构筑了 31 个具有 双核、四核、五核、六核、一维及二维结构的配合物，初步探讨了氮氧吡啶基团位置的变 化对配合物结构的影响以及不同配位抗衡离子的使用对稀土离子的配位构型、最终配合物 结构和磁学性质的影响。其中，2-氮氧吡啶酰基-(2-羟基)苯腙席夫碱配体与硝酸镝在不同 条件下组装得到互为同分异构体的一维链状和双核化合物，其中两个硝酸根分别为位于反 式和顺式位置。磁性研究表明双核化合物在零直流场下具有明显的热磁弛豫行为(能垒为 64.5 K)，而一维链状化合物则没有热弛豫行为，这是首次在稀土体系发现阴离子位置的变 化对热弛豫行为的影响。此外，还利用 2-氮氧吡啶酰基-(2-羟基)苯腙席夫碱配体与氯化镝 组装得到的一维链状配合物，其在零直流场下具有明显的慢磁弛豫行为，热弛豫能垒为 227 K，是目前酰腙席夫碱-稀土体系的最高能垒。另外，运用 4-氮氧吡啶酰基-(2-羟基-3-甲氧 基)苯腙席夫碱配体与醋酸镝组装得到了一例具有二维结构的稀土分子纳米磁体，磁性研究 表明其客体分子能够调节骨架的磁弛豫行为，是一例罕见的客体分子调节骨架磁弛豫行为 的体系，为调节磁弛豫行为提供了一个新思路。 2、使用吡啶酰腙席夫碱配体与镝盐构筑了 3 个具有双核结构的稀土分子纳米磁体， 并采取配位驱动自主装的方法用甲酸或乙酸根把这些双核基元连接形成了系列链状结构， 甲酸或乙酸根的引入不但将稀土分子纳米磁体连接成一维结构，而且也提高了体系的热弛 豫能垒，这为合成具有新颖结构的分子纳米磁体提供了新方法。 3、详细表征了这些配合物的磁弛豫行为，初步探索了结构与磁性之间的关系。除此 之外，还运用理论计算方法探讨了这些磁弛豫行为的来源以及磁弛豫途径。

The synthesis and magnetic property study of lanthanide molecular nanomagnet is the cornerstone of molecular-based magnetism. We synthesized thirty-six novel dysprosium complexes with carbohydrazine Schiff-base ligand and deeply studied their magnetic properties, constructing series of lanthanide molecular nanomagnets. Our work covers the following aspects: 1. Thirty-one novel dysprosium complexes with dinuclear, tetranuclear, pentanuclear, hexanuclear, one-dimensional and two-dimensional structures have been successfully constrcuted from a series of new pyridine-N-oxide carbohydrazine Schiff-base ligand. We preliminary discussed the effects of pyridyl-N-oxide’s position on the final structures of complexes, and investigated the influences of different coordinated counter ions on the coordinated configuration of lanthanide ions, the final structure of complexes and magnetic properties. Among them, two isomers with one-dimensional and dinuclear structures were synthesized with the assembly of N'-(2-hydroxybenzylidene)pyridine-N-oxide-carbohydrazide and dysprosium nitrate under different reaction conditions, where the two coordinated nitrate are trans or cis with respect to each other. Magnetic studies indicate that dinuclear compound shows obvious slow magnetic relaxation under zero dc field with an effective energy barrier Ueff of 64.5 K, while no relaxation signal was obesrved for one-dimensional compound. This is the first discovery that the position change of coordinated anions can dramatically alter the relaxation behavior of lanthanide molecular nanomagnet. In addition, a novel 1D dysprosium complex 16 was also synthesized with the assembly of N'-(2-hydroxybenzylidene)pyridine-N-oxidecarbohydrazide and dysprosium chloride, which exhibits slow magnetic relaxation with an energy barrier of 227 K under zero dc field. It is noteworthy that the energy barrier of 16 is the largest among lanthanide-carbohydrazine containing complexes. What is more, a novel two-dimensional lanthanide molecular nanomagnet was successfully synthesized from N′-(2-hydroxy-3-methoxybenzylidene)pyridine- N-oxide-carbohydrazide and dysprosium acetate. Magnetic studies indicate that guest molecules can tune the magnetic relaxation behavior of frameworks, which represents one of the very few lanthanide-organic frameworks that display rather rare, reversible, guest-dependent magnetic behavior, offering a new way to modulate the magnetic relaxation behavior of lanthanide-based magnetic systems. 2、Three dinuclear dysprosium molecular nanomagnet were constructed by reacting pyridine carbohydrazine Schiff-base ligand with different dysprosium salts, which was further connected to one-dimensional structure with formate group or acetate group as linkers by coordination-driven self-assembly method. The introduction of formate group or acetate group not only links the dinuclear subunit to one-dimensioal structure but also increases the effective energy barrier of compounds, providing us a promising strategy for the design of novel lanthanide-based magnetic materials. 3、The magnetic relaxation behaviors of most compounds were characterized and the relationship between structures and magnetic properties were preliminarily discussed. In addition, we also employed theoretical calculation to explore the origin and the path of slow magnetic relaxtion.