Synthesis and Properties of Photomagnetic Molecular Switches based on Spin Crossover Iron(II) Complexes Featuring Photoisomerizable Ligands

自旋交叉（SCO）金属配合物是最著名的一类分子磁系统，其磁性可以通过改变温度、施加的压力、电场和磁场或用光照射可逆地切换。最常见的SCO物种是铁（II）络合物，它提供了一个极好的机会，通过外部刺激在反磁性低自旋和顺磁性高自旋状态之间切换。通过光照射控制分子的状态是非常有吸引力的，这是由于非常高的切换速度，容易和精确的寻址和高选择性，这表明SCO络合物作为分子电子学和自旋电子学，通信网络，超高密度存储器等的光可切换构建模块的应用。最近，我们开发了一种独特的分子开关1 -SCO铁（II）配合物，其特征在于光活性二芳基乙烯衍生的配体L。将可光致异构化的配体L整合到SCO物种1中使我们能够在室温（RT）下用光以中等效率可逆地切换磁性。在本工作中，我们将化学修饰配体L，并合成相应的SCO铁（II）配合物。提出的L的化学修饰追求以下目标：1）改善基于1的分子开关的物理化学性质，2）增加开关的热稳定性，3）增加RT下的光磁效应，4）允许将分子开关接枝到金表面。因此，一个完整的家庭的分子开关的基础上的母配合物1将被合成和它们的光磁性能将在溶液中和在固态下进行研究。初步实验嫁接分子开关的金表面和调查他们的光磁性能在表面将进行。在这个项目上获得的结果可能会打开一个很好的机会，在RT下用光有效地和可逆地切换薄膜中的分子和单分子的磁性，可以在RT下的分子电子学和自旋电子学中找到不同的应用。

Spin crossover (SCO) metal complexes are among the best known classes of molecular bistable systems which magnetic properties can be reversibly switched by changing temperature, applied pressure, electric and magnetic field, or irradiation with light. The most common SCO species are iron(II) complexes that offer a brilliant opportunity to switch between a diamagnetic low-spin and paramagnetic high-spin states via external stimuli. Controlling a molecule's state via light irradiation is very attractive due to the extraordinary high speed of switching, easy and precise addressing and high selectivity that suggests application of SCO complexes as photoswitchable building blocks for molecular electronics and spintronics, communication networks, ultra-high density memories, and others. Recently we developed a unique molecular switch 1 - a SCO iron(II) complex featuring a photoactive diarylethene derived ligand L. The integration of the photoisomerizable ligand L into the SCO species 1 allowed us to switch reversibly magnetic properties with moderate efficiency with light at room temperature (RT). In the present work we will chemically modify the ligand L and synthesize corresponding SCO iron(II) complexes. The proposed chemical modifications of L pursue the following goals: 1) to improve the photophysical properties of molecular switches based on 1, 2) to increase the thermal stability of the switches, 3) to increase a photomagnetic effect at RT, 4) to allow the grafting of molecular switches to the gold surface. Thus, a whole family of molecular switches based on the parent complex 1 will be synthesized and their photomagnetic properties will be investigated in solution and in the solid state. Initial experiments on grafting of molecular switches to the gold surface and investigation of their photomagnetic properties at the surface will be performed. The results obtained on this project may open a great opportunity to switch efficiently and reversibly magnetic properties of molecules in thin films and single molecules with light at RT that could find diverse applications in molecular electronics and spintronics at RT.