Project Details
Projekt
Intramolecular interactions in di- and trinuclear Fe(II) spin-crossover complexes - X-ray absorption, quantum-chemical and THz-spectroscopic investigations
Subject Area
Inorganic Molecular Chemistry - Synthesis and Characterisation
Experimental Condensed Matter Physics
Theoretical Chemistry: Molecules, Materials, Surfaces
Experimental Condensed Matter Physics
Theoretical Chemistry: Molecules, Materials, Surfaces
Term
since 2025
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 561091420
The possibility of switching their magnetic moment on and off by external stimuli makes spin crossover (SCO) molecules highly interesting for applications, for example as programmable devices in molecule-based spin electronics. Important in this respect is the cooperativity of the spin-switching, which in bulk materials is mainly caused by elastic interactions between the molecules. In addition to such intermolecular interactions, intramolecular interactions in multinuclear SCO complexes can also lead to cooperative behaviour. In the present project, we aim at a fundamental understanding of spin switching in polynuclear SCO complexes, including the influence of the environment. By combining chemical synthesis, spectroscopic investigation and quantum-chemical simulations, we want to improve switchability on the one hand and to obtain a greater switching response on the other. For this purpose, new dinuclear and trinuclear Fe(II) complexes are synthesised in which the individual Fe(II) centres have SCO properties and are connected to each other by small aromatic bridging units. These systems are then analysed by X-ray absorption spectroscopy and Fourier transform THz electron paramagnetic resonance spectroscopy, a new method in the investigation of SCO molecules, and compared with those of the corresponding mononuclear analogues. These investigations are accompanied and supported by high-level quantum chemical calculations. Both, bulk materials as well as thin films on solid surfaces, down to sub-monolayers, are analysed. For the latter, the complexes are deposited on solid surfaces in ultra-high vacuum, if possible, by thermal evaporation, otherwise by pulsed liquid jet injection. The aim is to determine the temperature- and light-induced SCO properties, in particular to elucidate whether full or only partial switching of the individual Fe(II) centers can be achieved. Furthermore, we want to experimentally determine and theoretically reproduce the type and magnitude of intramolecular magnetic coupling and a possible magnetic coupling between the molecules and a ferromagnetic substrate. Of particular interest is whether evidence of vibronic coupling between the individual Fe(II) centres can be found.
DFG Programme
Priority Programmes
Subproject of
SPP 2491:
Interactive Spin-State Switching
