在环胺单分子磁铁中,磁性歇斯底里斯高达73K
Jack Emerson-King1, Jack Baldwin1, Sophie C Corner1
1Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
Journal of the American Chemical Society
|September 18, 2025
概括
这项研究引入了一种新的dysprosium单分子磁铁 (SMM),它结合了独特的连接物. 在实现高磁性异构的同时,其灵活的结构限制了潜在的高温SMM应用的阻塞温度.
科学领域:
- 协调化学
- 材料科学
- 量子计算
背景情况:
- 基于dysprosocenium电离子 ([Dy(CpR) 2]+) 的单分子磁体 (SMM) 由于轴向晶场和刚性体,具有高磁逆转障碍 (Ueff) 和阻断温度 (TH).
- 二胺) 离子 ([Dy(NR2) +) 通过充电密度较高的N-捐赠体的强轴场提供了优越的SMM特性,但联体灵活性可以增加磁放松并降低TH.
研究的目的:
- 合成和表征一种新型的dysprosium复合物,该复合物结合了π-芳和单胺连体,以利用这两种连体类型在SMM应用中的优势.
- 研究新型复合物的磁性特性,特别是有效能量屏障 (Ueff) 和阻断温度 (TH).
主要方法:
- 复合物的合成[Dy{N(SiiPr3) 2}(Cp*) ]Al{OC(CF3) 3}4 (1-Dy).
- 磁性表征,包括测量磁性异构和温度依赖的磁性歇斯底里,以确定U和T.
- 分子几何分析,包括N-Dy-Cp*cent角度,以与观察到的磁性特征相关联.
主要成果:
- 合成的复合物1-Dy具有很大的磁性异构,Ueff = 2191(33) K,与领先的基于dysprosium CpR的SMM可比.
- 观察到的阻断温度TH为73K,低于记录值,这归因于曲联体几何和灵活的胺替代物.
- 结构分析显示曲的N-Dy-Cp*cent角大约为152.5(2)°,影响磁放松通路.
结论:
- 具有一个π-芳香和一个单联体的dysprosium SMM可以达到高的Ueff值,类似于bis-π-芳香系统.
- 这些复合物表现出对连接方角的敏感性,影响阻隔下放松,类似于bis (胺) 复合物.
- 这一新类型的复合物对高温SMM具有前景,通过精确的分子几何控制可以显著改善.
相关概念视频
01:31Ferromagnetism
3.0K
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
3.0K
01:30Paramagnetism
3.0K
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...
3.0K
01:31Magnetic Susceptibility and Permeability
2.3K
In linear magnetic materials, like paramagnets and diamagnets, magnetization is proportional to the magnetic field intensity. The constant of proportionality, a dimensionless number, is called magnetic susceptibility. The value of the susceptibility depends on the type of material.
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
2.3K
01:26Diamagnetism
2.9K
Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets....
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets....
2.9K
01:15¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
1.7K
The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.
1.7K
01:27π Electron Effects on Chemical Shift: Overview
1.6K
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0,...
1.6K