Solvent dependence of crystal structure and dielectric relaxation in ferromagnetic [MnCr(oxalate)3]- salt
Solvent dependence of crystal structure and dielectric relaxation in ferromagnetic [MnCr(oxalate)3]- salt
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铁磁 [MnCr(草酸)3]-盐中晶体结构和介电弛豫的溶剂依赖性
DOI：
10.1039/d2dt01615j
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发表时间：
2022
影响因子：
4
通讯作者：
Nakamura Takayoshi
中科院分区：
文献类型：
--
作者：
Wu Jia-bing;Huang Rui-Kang;Takahashi Kiyonori;Nakamura Takayoshi
[MnCr（oxalate）3]−具有二维铁磁网络，是构建基于铁磁性的多功能分子材料的理想体系。这是因为额外的功能，如铁电性，可以通过在层之间引入功能阳离子来混合。然而，大多数[MnCr（oxalate）3]−网络在结晶时容易结合溶剂分子，并且有时难以测量晶体物理性质，因为与去溶剂化相关的崩溃。在去溶剂化后，极性晶体（CBA+）（[18]crown-6）[MnCr（oxalate）3]−（CH 3OH）（1·CH 3OH）（CBA+ = 4-carboxybutan-1-aminium）经历晶体到晶体的转变，形成（CBA+）（[18]crown-6）[MnCr（oxalate）3]−，1.此外，这种变化伴随着（CBA+）（[18]冠-6）超分子组装中的氢键重组。这两种晶体在约5 K时都表现出铁磁有序性。在晶体1中，观察到[18]冠-6的“旋转木马”运动，活化能为41.41 kJ mol-1，导致介电弛豫。这种晶体到晶体的结构转变提供了一种设计多功能杂化材料的策略，其中分子运动产生了额外的功能。
[MnCr(oxalate)3]− possesses a two-dimensional ferromagnetic network that is an ideal system for the construction of multifunctional molecular materials based on ferromagnetism. This is because additional functions, such as ferroelectricity, can be hybridised by incorporating functional cations between the layers. However, the majority of [MnCr(oxalate)3]− networks readily incorporate solvent molecules upon crystallisation, and it is sometimes difficult to measure the crystal physical properties because of the collapse associated with desolvation. Upon desolvation, the polar crystal (CBA+)([18]crown-6)[MnCr(oxalate)3]−(CH3OH) (1·CH3OH) (CBA+ = 4-carboxybutan-1-aminium) underwent a crystal-to-crystal transformation to form (CBA+)([18]crown-6)[MnCr(oxalate)3]−, 1. Furthermore, this change was accompanied by hydrogen bond reorganisation in the (CBA+)([18]crown-6) supramolecular assembly. Both crystals exhibited ferromagnetic ordering at approximately 5 K. In crystal 1, a “merry-go-round” motion of [18]crown-6 was observed, with an activation energy of 41.41 kJ mol−1, which resulted in dielectric relaxation. This crystal-to-crystal structural transformation provides a strategy for designing multifunctional hybrid materials, in which an additional function arises from molecular motion.