稀土分子纳米磁体的可控组装和磁性调控

The control assembly and magnetic property tuning of lanthanide molecular nanomagnet are the frontier and hot field of molecular magnetism, which research results are helpful for further understanding the origination of slow magnetic relaxation in complicated lanthanide systems and thus widen their application in this field. Our project focus on the rational assemble of lanthanide molecular nanomagnets by chemical methods. One approach for the assembly is by the design and synthesis of novel shiff-base ligands containing multi pyridine-N-oxide-carbohydrazide groups that can coordinate to lanthanide ions in special ways. Another approach for the assembly is by introducing coordination groups to the pyridine-N-oxide-carbohydrazide-containing shiff base ligands that can build lanthanide molecular nanomagnets or by linking these lanthanide molecular nanomagnets through various bridging ligands. The other way for the assembly is by employing chelate and bridging ligands together and the bridging ligands can link the building blocks constructed by the chelate ligands and lanthanide ions, resulting in lanthanide systems with novel crystal structure and slow magnetic relaxation. After the successfully construction of these lanthanide assembly systems, we plan to explore the influence of assembly process on coordination environment around lanthanide ions or their symmetry, the linkage between the lanthanide ions, and the final magnetic behavior. And the influence for easy-axis alignment of lanthanide ions and the interaction between different molecular nanomagnets on the final slow magnetic relaxation of assembly systems with special crystal structure will be further investigated. Our reach results can give some clue for the understanding the slow magnetic relaxation in complicated lanthanide systems.

稀土分子纳米磁体的可控组装和磁性调控是当前分子磁学的热点领域，该研究既有助于理解复杂稀土体系中磁弛豫的来源，又可以拓宽稀土离子在分子磁性领域的应用。本项目着眼于通过化学的手段理性实现稀土分子纳米磁体的可控组装，拟通过设计合成新颖的氮氧吡啶多酰肼西弗碱配体，通过在能够形成稀土分子纳米磁体的氮氧吡啶酰肼西弗碱配体上引入配位基团，运用这些氮氧吡啶酰肼西弗碱配体与其他桥联配体相结合的方法，运用螯合配体与桥联配体相结合的策略，结合不同的稀土盐，考虑配位场理论，构筑具有新颖结构和磁弛豫行为的组装体系；探讨组装过程对稀土离子周围配位环境和构型、稀土离子间连接的影响以及体系磁学性质的调节；探索具有特殊结构的组装体系中稀土离子磁各向异性轴排列和组分间磁相互作用对组装体系磁弛豫行为的影响，为深入了解复杂稀土体系的磁弛豫行为提供理论基础。

稀土分子纳米磁体的可控组装和磁性调控是当前分子磁学的热点领域，该研究既有助于理解复杂稀土体系中磁弛豫的来源，又可以拓宽稀土离子在分子磁性领域的应用。本项目主要着眼于通过化学的手段理性实现稀土分子纳米磁体的可控组装，通过设计合成新颖的席夫碱类和嘧啶羧酸类配体，通过引入不同配位基元（氮氧吡啶、氮氧吡嗪或羧酸）或第二配体，运用混合配体和结构基元的策略，通过配位驱动自组装的方法实现了稀土分子纳米磁体在晶态材料中多尺度和多维度的可控组装；探讨了组装对稀土离子的配位环境及磁各向异性，稀土离子间的连接及磁相互作用，以及配合物磁驰豫行为的调控；对一些具有特殊结构的组装体系，深入探讨了稀土离子磁各向异性轴的排列和稀土离子间的磁相互作用对体系磁弛豫行为的影响机制，为深入了解复杂稀土体系的磁弛豫行为提供理论基础。在本项目的执行过程中，我们设计合成了8类席夫碱或嘧啶羧酸类配体，在11个体系实现了稀土分子纳米磁体在晶态材料中的可控组装和性能调控，获得了45例具有动态磁驰豫行为的镝配合物。研究发现，通过选择合适的组装策略和使用不同的桥联配体，组装的确能够改变镝离子的配位环境，增强镝离子的磁各向异性，实现磁驰豫行为，提高磁驰豫能垒；同时，组装也能够实现或调节镝离子间的连接，引入或改变稀土离子间的磁相互作用，影响量子隧穿过程或磁驰豫途径，从而增强或淬灭热驰豫过程；另外，实现稀土分子纳米磁体可控组装的同时也可以形成微孔结构，实现了客体分子对磁驰豫行为的调控以及质子导电性质的引入，实现多功能磁驰豫体系的构筑。基于这些研究成果，在项目执行过程中我们在高水平专业学术期刊上发表了11篇SCI论文，另有4篇论文在整理或投稿中。