A Magneto‐optical Molecular Device: Interplay of Spin Crossover, Luminescence, Photomagnetism, and Photochromism

Abstract

A bis(pyrazolylpyridyl) ligand, L, containing a central photochromic dithienylethene spacer predictably forms a ferrous [Fe₂ L₃ ]⁴⁺ helicate exhibiting spin crossover (SCO). In solution, the compound [Fe₂ L₃ ](ClO₄ )₄ (1) preserves the magnetic properties and is fluorescent. The structure of 1 is photo-switchable following the reversible ring closure/opening of the central dithienylethene via irradiation with UV/visible light. This photoisomerization switches on and off some emission bands of 1 and provides a means of externally manipulating the magnetic properties of the assembly.