Reversible single crystal photochemistry and spin state switching in a metal-cyanide complex
- Michał Magott
- Mirosław Arczyński
- Leszek Malec
- Michał Rams
- Mathieu Rouzières
- Andrei Rogalev
- Fabrice Wilhelm
- Itziar Oyarzabal
- Thomas Lohmiller
- Alexander Schnegg
- Coen de Graaf
- Corine Mathonière
- Rodolphe Clérac
- Dawid Pinkowicz
2025-09-29
Manipulating the physical properties of solid matter using only photons is a major challenge in materials science. However, achieving such control over a chemical reaction in the solid state is even more challenging. Here we demonstrate the reversible photochemistry occurring in a single crystal of a simple cyanide complex, K 4 [Mo III (CN) 7 ]·2H 2 O. Upon exposure to visible light at different wavelengths, a reversible breaking and reformation of dative bonds is triggered, resulting in a photoswitching of the Mo III coordination geometry between 6- and 7-coordinate. This transformation, in turn, induces a spin state change. The observed solid-state photochemical reactivity is robust, quantitative and occurs at a record-high temperature. It paves the way for the development of new photo-switchable high-temperature magnets and nanomagnets.