基于过渡−稀土异三金属纳米分子磁体的定向构筑与磁性能研究

Nano-molecular magnets (single-molecule/single-chain magnets), which exhibit a slow relaxation of the magnetization with a magnetic hysteresis analogous to bulk magnets and quantum tunneling of the magnetization at low temperature (below the magnetic blocking temperature), present potential applications in high-density information storage, quantum computing, etc. All along, to improve the magnetic blocking temperatures of single-molecule/single-chain magnets has been pursued by researchers. Some lanthanide (4f) ions not only have larger ground-state spins and strong single-ion anisotropy, but also usually exhibit strong ferromagnetic interaction with paramagnetic transition metal (3d/4d/5d) ions. So it is an effective strategy to introduce lanthanide ions into transition metal complexes to improve the magnetic blocking temperatures of single-molecule/single-chain magnets. With those in mind, by choosing the suitable organic ligands and the paramagnetic metal ions, introducing the third 3d/4d/5d ion into the transition–lanthanide heterobimetallic complex to make them exhibit strong ferromagnetic interactions between transition–transition metal ions and transition–lanthanide ions, and the lanthanide ions with the strong single ion anisotropy as a main component to provide the magnetic anisotropy within clusters or chains, we intend to synthesize 3d/4d/5d−4f heterotrimetallic single-molecule/single-chain magnets with the higher magnetic blocking temperature based on the complex ligands and node-and-spacer approaches. Finally, the relationships between magnetism and structures of the target compounds are analyzed. Based on that, we will provide further theoretical and experimental basis for the development and application of single-molecule/single-chain magnets.

纳米分子磁体（单分子/单链磁体），在低温（磁阻塞温度）下表现出类似传统磁体的磁滞行为，显示缓慢的磁弛豫作用，同时具有量子隧穿效应，使得它们在高密度信息存储、量子计算机等方面具有潜在的应用前景。一直以来，合成高磁阻塞温度的单分子/单链磁体是研究者孜孜不倦的追求。本项目拟采用配合物作配体法和结点法，通过选择合适的有机配体和顺磁性金属离子，在过渡−稀土异双金属化合物的基础上再引入其它的顺磁性过渡金属离子，使过渡金属离子间、过渡−镧系离子间传递强的铁磁交换作用，具有强旋轨耦合的镧系离子作为提供簇内或链内磁各向异性的主要组成部分来合成磁阻塞温度更高的过渡−稀土异三金属单分子/单链磁体，并对所合成的目标产物进行磁构关系研究，为单分子/单链磁体的开发及应用提供进一步的理论和实验依据。

纳米分子磁体（单分子/单链磁体），在低温（磁阻塞温度）下表现出类似传统磁体的磁滞行为，显示缓慢的磁弛豫作用，同时具有量子隧穿效应，使得它们在高密度信息存储、量子计算机等方面具有潜在的应用前景。一直以来，合成高磁阻塞温度的单分子/单链磁体是研究者孜孜不倦的追求。本项目中，我们主要进行了三个系列过渡-稀土异单分子磁体的制备与磁性能研究，包括：（1）过渡-稀土异三金属配合物的制备与磁性能研究，（2）系列3d-4f异金属配合物的制备与磁性研究，（3）高核顺磁性4f,3d-4f异金属配合物的制备与磁性研究。我们成功地通过改变、控制桥联配体的取向（比如硝酸根，多氰基金属单元）、镧系离子的空间构型，使整个团簇呈现强的单轴各向异性，从而得到具有较高有效翻转能垒的单分子磁体。这为单分子磁体的设计和磁性能研究提供新的实验和理论依据。另外，我们开展了导电磁体方面的研究，合成了系列含TCNQ的稀土配合物，部分配合物呈现较好的磁性。由于TCNQ间通过π···π相互作用形成柱堆积，有望得到导电磁体。