丹麦技术大学Pedersen, Kasper S.团队报道了镧系有机合金的可调价互变异构。相关研究成果于2024年2月19日发表在国际顶尖学术期刊《自然—化学》。

镧系元素（Ln）离子无与伦比的电子结构是涉及包含这些元素的先进材料和技术的关键。三价离子是普遍存在的，并且比二价和四价类似物使用得更广泛，后者具有截然不同的光学和磁性。因此，外部刺激引起的价电子计数的改变会导致材料性质的剧烈变化。表现出温度诱导的完全Ln(III)Ln(II) 转换（称为价互变异构体（VT）转变）的化合物是罕见的。

该文中，研究人员提出了镧系配位聚合物SmI₂（吡嗪）₃中的突然和滞后的VT转变，由Sm（II）-吡嗪（0）和Sm（III）-吡唑（·-）氧化还原对的相互转化驱动。SmI₂（吡嗪）₃与Yb（II）合金化可产生同晶Sm_1–xYb_xI₂（吡嗪）₃固溶体，室温转变临界温度范围为200K～50K。这些发现证明了实现具有化学可调转变温度的可热切换磁性材料的简单策略。

附：英文原文

Title: Tunable valence tautomerism in lanthanide–organic alloys

Author: Dunstan, Maja A., Manvell, Anna S., Yutronkie, Nathan J., Aribot, Frdric, Bendix, Jesper, Rogalev, Andrei, Pedersen, Kasper S.

Issue&Volume: 2024-02-19

Abstract: The inimitable electronic structures of the lanthanide (Ln) ions are key to advanced materials and technologies involving these elements. The trivalent ions are ubiquitous and are used much more widely than the divalent and tetravalent analogues, which possess vastly different optical and magnetic properties. Hence, alteration of the valence electron count by external stimuli can lead to dramatic changes in materials properties. Compounds exhibiting a temperature-induced complete Ln(III)Ln(II) switch, referred to as a valence tautomeric (VT) transition, are rare. Here we present an abrupt and hysteretic VT transition in a lanthanide-based coordination polymer, SmI2(pyrazine)3, driven by the interconversion of Sm(II)–pyrazine(0) and Sm(III)–pyrazine(·) redox pairs. Alloying SmI2(pyrazine)3 with Yb(II) yields isomorphous Sm1–xYbxI2(pyrazine)3 solid solutions with VT transition critical temperatures ranging widely from 200K to ～50K at ambient pressure. These findings demonstrate a simple strategy to realize thermally switchable magnetic materials with chemically tunable transition temperatures.

DOI: 10.1038/s41557-023-01422-8

Source: https://www.nature.com/articles/s41557-023-01422-8