光诱导磁双稳态材料

Bistability is an important property associated with memory and switching functions, which could ultimately be utilized for the elaboration of molecule-based devices. In particular, the control of magnetic bistability by light will be an important target in the future. Unfortunately, most phototunable magnetic materials work only below liquid-nitrogen temperature, and it will be important to find a way of being able to operate at room temperature. Since photochromic molecules exhibit bistability even at room temperature, ligand-driven light-induced spin change (LD-LISC), which combines photochromic molecule with spin crossover material, provides a useful approach for achieving photomagnetic switching at room temperature. Recently, several LD-LISC systems had been successfully demonstrated in the solid state at room temperature. However, only one-way photochromism was identified and modulation of the magnetism was trivial at room temperature, because the photoisomerization of organic photochromics was considered to require a certain degree of free volume. In order to obtain reversible LD-LISC materials with high photoswitching efficiencies and larger modulations of the magnetism, we'll focus on the following works: 1) New mechanisms of the photoisomerization and large counter anion will be introduced into the mononuclear LD-LISC system to increase the free volume around photochromics. 2) Photochromic guest molecules will be trapped into the porous spin crossover materials. 3) Photochromic bridging ligands will be directly used to construct porous photo-induced magnetic bistable materials.

双稳态具有存储和开关功能最终可用于构筑分子器件，其中用光来控制磁双稳态性质在未来应用中尤为重要。目前大多数光诱导磁性材料仅在液氮温度下工作，因而能在室温运行的途径至关重要。光致变色分子可在室温显示双稳性质，将它与自旋交叉相结合形成的配体驱动光诱导自旋转变材料可在室温实现光磁开关行为。最近此类体系已有在固态和室温下成功转变的例子，然而由于有机光色体在光异构化过程中需要一定的自由空间，其结果仅显示单向光致变色行为和较小的磁性变化。为获得高的光开关效率和大的磁性调控且可逆的配体驱动光诱导自旋转变材料，我们将开展以下方面工作：1）引入新的光异构化机理和大的抗衡阴离子到单核配体驱动光诱导自旋转变材料中去，以提高光色体周围的自由空间；2）将光致变色分子作为客体引入到孔洞型自旋交叉材料中去；3）采用光致变色桥连配体直接构筑孔洞型光诱导磁双稳态材料。

双稳态具有存储和开关功能最终可用于构筑分子器件，其中用光来控制磁双稳态性质在未来应用中尤为重要。将光致变色分子与自旋交叉相结合有望开发室温光诱导磁双稳态材料。为此，在光诱导磁双稳态材料的合成方面，我们紧密围绕研究计划从三个方面进行了探索：1）引入新的光异构化机理和大的抗衡阴离子以合成单核配体驱动光诱导自旋交叉材料；2）将光致变色分子作为客体引入到金属有机框架材料中以合成主客体型光诱导自旋交叉材料；3）利用光致变色桥连配体直接构筑孔洞型光诱导自旋交叉材料。在磁构关系考察方面，我们探索了客体、配体取代基效应和空间效应对自旋交叉性质的影响，从而对光诱导磁双稳态材料性能优化提供指导。我们还在自旋交叉材料器件化方面进行了探索，研究了室温或高温自旋交叉材料和导电自旋交叉复合体，为材料的器件化和实际应用作了前期的摸索。经过四年的努力，我们在以下方面获得了重要进展：1）合成了系列具有优异客体响应自旋交叉性质的金属有机框架材料，尤其是我们获得了首例具有HS0.0LS1.0 ~ HS0.25LS0.75 ~ HS0.5LS0.5 ~ HS0.75LS0.25 ~ HS1.0LS0.0序列的回滞型四步自旋交叉材料，并通过溶剂交换首次实现了四步、两步和一步自旋交叉性质间的可逆转变。2）深入剖析了霍夫曼型金属有机框架材料中客体对自旋交叉性质的影响因素。3）获得了两例具有光诱导激发自旋态捕获效应的材料。4）在导电自旋交叉复合体系中成功的实现了自旋交叉性质与导电的协同双稳，为材料的器件化提供了新方案。本项目共发表学术论文12篇，包括1篇Angew. Chem. Int. Ed.、1篇Coord. Chem. Rev.、2篇Chem. Eur. J.、2篇J. Mater. Chem. C、4篇Inorg. Chem.、1篇Inorg. Chem. Front.、和1篇Crystengcomm。