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

• Applicant: Privatdozent Dr. Marat Khusniyarov
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 255181289

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.

• DFG Programme: Research Grants