镝酰腙配合物制备的微量热学及磁性研究

本课题选择具有大的自旋基态和强的磁各向异性的稀土镝(Dy3+)离子作为顺磁中心，以鳌合配位能力强、配位模式丰富的多齿酰腙类希夫碱作为有机配体，设计和组装新型配合物分子磁体，基于修饰配体和溶剂变换等因素对体系自组装行为的影响，获得结构多样的有序组装体，合理构建配体场微扰中心离子的几何构型和电荷分布，调控其结构和磁性，结合实验和理论计算探究构效关系及磁弛豫机理。利用微量热测量系统对Dy3+配合物分子磁体的组装历程实施动态跟踪，获得反应进程中体系的热动力学信息，确定自组装行为的能量控制因素，阐明分子间相互作用的协同性和方向性，探寻配合物分子磁体自组装行为与热力学的关系，揭示配合物分子磁体的组装规律及热力学驱动内因，实现配合物分子磁体自组装过程的精准控制。系统的磁学研究和热力学性质研究对选择性设计和合成高性能配合物分子磁体及揭示化学自组装多组分、多层次构筑的内在规律具有重要的理论及应用意义。

In present project, Dy(III) ion is identified to be paramagnetic center due to its large Kramers ground state and significant magnetic anisotropy, while polydentate acylhydrazone derivatives are selected as organic ligands owing to their superior chelate effect and diverse coordination modes with metal ions. The integration of the two candidates above is employed to design and assemble novel Ln(III)-based molecular magnets. As a result, the ordered self-assembly systems of Dy(III)-containing molecular magnets would be prepared and affected by modified ligands and alternative solvents, in which the coordination geometries and charge distributions of central Dy(III) ions are significantly perturbed by regulating ligand-fields, leading to the fine-tuning of the structures and magnetisms of target products. The magneto-structural correlation and magnetic relaxation mechanism are explored by the combination of theoretical calculation and experimental measurement. The dynamic tracings in the assembling process of Dy(III) molecular magnets are performed by using microcalorimetry measurement systems, obtaining the thermodynamic data of the courses and determining the energetic controlling factors of the self-assembly behaviors. The research results would illuminate the cooperativity and directivity of the intermolecular interactions, which are conductive to probe the relationships between self-assembly behaviors and thermodynamic properties, as well as reveal the assembling rules and thermodynamic internal causes, finally realizing the accurate control for the formations of complex-based molecular magnets. Systematic studies on magnetism and thermodynamics would provide importantly theoretical and practical significances for selectively designing and assembling the high-performance molecular magnets and deeply understanding the inherent laws of multi-component and multi-layered constructions in chemical self-assembly.