| 第一过渡系金属-镝单分子磁体研究进展与展望 |
| Research Progress and Prospect on the First Series Transition Metal-Dy Single Molecule Magnets |
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| 摘要: 第一过渡系中的顺磁性离子CrⅢ、MnⅡ/MnⅢ、FeⅡ/FeⅢ、CoⅡ、NiⅡ和CuⅡ及抗磁性离子CoⅢ和ZnⅡ均可与DyⅢ在多齿螯合配体配位下形成单分子磁体配合物。在本文中，我们阐述或汇总了几乎所有的第一过渡系金属-镝单分子磁体。对于由顺磁性第一过渡金属离子和DyⅢ离子形成的配合物，有2个有趣的现象需要引起人们的注意：一是一些Cr-Dy配合物具有较高的阻塞温度和较大的矫顽场，这可归功于配合物内CrⅢ离子和DyⅢ离子之间较强的磁耦合作用（|J|>10 cm-1）。二是报道的FeⅡ2-Dy配合物的能垒可达到319 cm-1（459 K），这在第一过渡系金属-镝单分子磁体中也是比较高的。这可能与FeⅡ2-Dy中DyⅢ具有较高的轴向对称性（D5h）有关，且从头计算表明该配合物中Dy的第一激发态也具有较高的轴向对称性。除了部分Cr-Dy和FeⅡ-Dy配合物外，其他顺磁性第一过渡金属-Dy的能垒较低，这可能由配合物内顺磁离子间弱的磁耦合造成的。为了消除磁耦合对磁弛豫行为影响，近年来人们关注于使用抗磁性第一过渡金属离子与DyⅢ构建单分子磁体配合物。相比其他核数的Zn-Dy配合物，三核Zn2Dy配合物被报道的数目最多且研究得最为深入，这可能与较易调控Zn2Dy中Dy配位几何对称性有关。最后，我们提出了几点关于进一步提升第一过渡系金属-镝单分子磁体的磁性能的建议，其中最为重要的是控制Dy配位几何的轴向对称性及Dy的基态mJ的电荷分布。对于第一过渡系金属-镝单分子磁体中的DyⅢ离子，DyⅢ基态mJ的电荷与配体的电荷之间的静电排斥应该降到最低。 |
| 关键词: 单分子磁体 第一过渡系金属-镝配合物 配位几何 易磁化轴 磁耦合作用 |
| 基金项目: 湖北省教育厅重点项目（No.D20191502）、国家自然科学基金青年基金（No.21201136）和武汉工程大学研究生创新基金（No.CX2019182）资助项目。 |
| Abstract: Among the first series transition metal (TM) ions, not only the paramagnetic TM ions (such as CrⅢ, MnⅡ/ MnⅢ, FeⅡ/FeⅢ, CoⅡ, NiⅡ and CuⅡ) but also diamagnetic TM ions (such as CoⅢ and ZnⅡ) can assemble with DyⅢ to form the TM-Dy single molecule magnets (TM-Dy SMMs). In this paper, we survey most of the TM-Dy complexes with SMM behavior. For the TM-Dy SMMs, two interesting phenomena should be emphasized on. One is some Cr-Dy complexes possessing relatively high blocking temperature (TB) and large coercivities, which could be ascribed to the strong magnetic couplings between CrⅢ and DyⅢ ions (|J|>10 cm-1). Another is the FeⅡ2-Dy complex with the energy barrier of 319 cm-1 (459 K), which is high among the TM-Dy SMMs. The reason might be that the axial symmetry of the coordination of DyⅢ ion is high (D5h). Additionally, ab initio calculations indicate the excited state also possess high axial symmetry. Besides the CrⅢ-Dy and FeⅡ2-Dy complexes, other TM-Dy SMMs usually exhibits relatively low energy barriers, which may be due to the weak magnetic interactions between paramagnetic TM ions and DyⅢ ions. To elimate the effect of the weak magnetic couplings on the relaxation behavior, the study of the DTM-Dy SMMs (DTM=diamagnetic the first series transition metal ions such as CoⅢ and ZnⅡ) has been received wide attention and their number is dramatically increasing. For the Zn-Dy SMMs, the number of the Zn2Dy trinuclear complexes is larger than that of other Zn-Dy complexes, indicating that the Zn2Dy received more attention. The reason might be that the coordination geometry of the DyⅢ in the Zn2Dy complexes can be more easily modulated. Finally, we provided some reseach thoughts for further improving the SMM performance of the TM-Dy complexes; the most important thoughts are that the axial symmetry of the coordination geometries of DyⅢ ions and the distribution of charge density of DyⅢ ions in TM-Dy complexes should be controlled. For DyⅢ in the TM-Dy complexes, the electrostatic repulsion between the DyⅢ ground-mJ charge density and the ligand charge density should be minimized. |
| Keywords: single molecule magnets the first series transition metal-Dy single molecule magnets coordination geometries easy magnetization axes magnetic couplings |
| 投稿时间：2020-06-28 修订日期：2020-10-02 |
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| 张柯,王会生,于灵燕,陈勇,潘志权.第一过渡系金属-镝单分子磁体研究进展与展望[J].无机化学学报,2020,36(12):2205-2226. |
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| Support information: 相关附件： file200305_Supporting_Information_for_CJIC.docx |
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