⁵⁷Fe Mössbauer Study on Photoinduced Spin Transition of Ferrocene in Polymer Matrices

A polymer matrix isolation technique was examined as a potentially novel strategy for realizing optically switchable materials. Not only was a ferricinium ion ([Cp₂Fe^III]⁺) produced, but also was produced an isomer of ferrocene (Cp₂Fe) with high spin Fe^II in a poly(methyl methacrylate) (PMMA) matrix film containing CCl₄ by the photoillumination of ferrocene at low temperature. The high spin state could be maintained for an extended period when the sample was kept below ≈ 130 K. This is the first observation of a photoinduced spin transition for ferrocene. The strategy that we used to achieve the spin transition using optical stimuli may open up many possibilities for the development of new magneto-optical devices.