Molecule-based spin state switching materials that display ambient temperature transitions with accompanying wide thermal hysteresis offer an opportunity for electronic switching, data storage, and optical technologies but are rare in existence. Here, we present the first 2D Hofmann-type materials to exhibit the elusive combination of ambient temperature spin crossover with wide thermal hysteresis (ΔT = 50 and 65 K). Combined structural, magnetic, spectroscopic, and theoretical analyses show that the highly cooperative transition behaviours of these layered materials arise due to strong host–host interactions in their interdigitated lattices, which optimises long-range communication pathways. With the presence of water molecules in the interlayer pore space in the hydrated phases, competing host–host and host–guest interactions occur, whilst water removal dramatically increases the framework cooperativity, thus affording systematic insight into the structural features that favour optimal spin crossover properties.

中文翻译：

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在去除客体分子的情况下增加 2D Hofmann 型材料的自旋交叉协同性†

基于分子的自旋态切换材料显示环境温度转变和伴随的宽热滞后，为电子切换、数据存储和光学技术提供了机会，但很少见。在这里，我们展示了第一个二维霍夫曼型材料，展示了环境温度自旋交叉与宽热滞后（ΔT= 50 和 65 K)。结合结构、磁性、光谱和理论分析表明，这些层状材料的高度协同跃迁行为是由于它们的叉指晶格中的强主体-主体相互作用而产生的，从而优化了远程通信路径。随着水合相层间孔隙空间中水分子的存在，发生竞争的主-主和主-客体相互作用，而水的去除显着提高了框架的协同性，从而系统地洞察有利于最佳自旋交叉特性的结构特征.