State Key Laboratory of Fine Chemicals, Dalian University of Technology, 2 Linggong Rd., 116024, Dalian, China.
Department of Chemistry, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto, 860-8555, Japan.
Angew Chem Int Ed Engl. 2017 Oct 9;56(42):13052-13055. doi: 10.1002/anie.201707258. Epub 2017 Sep 13.
It is an ongoing challenge to design and synthesize magnetic materials that undergo colossal thermal expansion and that possess potential applications as microscale or nanoscale actuators with magnetic functionality. A paramagnetic metallocyanate building block was used to construct a cyanide-bridged Fe-Co complex featuring both positive and negative colossal volumetric thermal-expansion behavior. A detailed study revealed that metal-to-metal charge transfer between 180 and 240 K induced a volumetric thermal expansion coefficient of 1498 MK accompanied with hysteretic spin transition. Rotation of the magnetic building blocks induced change of π⋅⋅⋅π interactions, resulting in a negative volume expansion coefficient of -489 MK , and another hysteretic magnetic transition between 300 and 350 K. This work presents a strategy for incorporating both colossal positive and negative volumetric thermal expansion with shape and magnetic memory effects in a material.
设计和合成具有巨热膨胀效应且可用作微尺度或纳米尺度具有磁功能致动器的磁性材料是一个持续的挑战。本文使用顺磁金属氰酸盐砌块构建了一种氰桥铁-钴配合物，其具有正和负巨体积热膨胀行为。详细研究表明，180 至 240 K 之间的金属-金属电荷转移诱导了 1498 MK 的体积热膨胀系数，并伴随着滞后自旋转变。磁性构建块的旋转引起了 π⋅⋅⋅π 相互作用的变化，导致-489 MK 的负体积膨胀系数，并且在 300 至 350 K 之间发生另一个滞后磁转变。这项工作提出了一种策略，可在材料中结合巨正和负体积热膨胀以及形状和磁记忆效应。
