具有镧系自旋的空气稳定的氧化还原活性纳米磁体通过金属-金属键自由基桥联。

Air-stable redox-active nanomagnets with lanthanide spins radical-bridged by a metal-metal bond.

机构信息

Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstrasse 20, 01069, Dresden, Germany.

Institute of Physical Chemistry and Chemical Physics, Slovak University of Technology, Radlinského 9, 81237, Bratislava, Slovakia.

出版信息

Nat Commun. 2019 Feb 4;10(1):571. doi: 10.1038/s41467-019-08513-6.

Engineering intramolecular exchange interactions between magnetic metal atoms is a ubiquitous strategy for designing molecular magnets. For lanthanides, the localized nature of 4f electrons usually results in weak exchange coupling. Mediating magnetic interactions between lanthanide ions via radical bridges is a fruitful strategy towards stronger coupling. In this work we explore the limiting case when the role of a radical bridge is played by a single unpaired electron. We synthesize an array of air-stable Ln@C(CHPh) dimetallofullerenes (Ln = Y, Gd, Tb, Dy, Ho, Er, TbY, TbGd) featuring a covalent lanthanide-lanthanide bond. The lanthanide spins are glued together by very strong exchange interactions between 4f moments and a single electron residing on the metal-metal bonding orbital. Tb@C(CHPh) shows a gigantic coercivity of 8.2 Tesla at 5 K and a high 100-s blocking temperature of magnetization of 25.2 K. The Ln-Ln bonding orbital in Ln@C(CHPh) is redox active, enabling electrochemical tuning of the magnetism.

工程学中，在磁性金属原子之间引入分子内交换相互作用是设计分子磁体的一种常用策略。对于镧系元素，4f 电子的局域性质通常导致较弱的交换耦合。通过自由基桥介导镧系离子之间的磁相互作用是增强耦合的一种有效策略。在这项工作中，我们探索了自由基桥的作用由单个未配对电子来扮演的极限情况。我们合成了一系列稳定的空气 Ln@C(CHPh)双金属富勒烯（Ln=Y、Gd、Tb、Dy、Ho、Er、TbY、TbGd），其特征是具有共价镧系-镧系键的。通过 4f 磁矩与位于金属-金属成键轨道上的单个电子之间的非常强的交换相互作用，镧系元素的自旋被胶合在一起。Tb@C(CHPh)在 5 K 时表现出 8.2 特斯拉的巨大矫顽力和 25.2 K 的高 100 秒磁化率阻断温度。在 Ln@C(CHPh)中，Ln-Ln 成键轨道具有氧化还原活性，能够对磁体进行电化学调节。