Teilprojekte

The main targets are the design, construction and deep understanding of novel molecule-based magnetic materials with optical read-out. This will be achieved by a combination of iron(II)/chromium(II) spin-crossover and luminescent chromium(III) complexes based on the molecular ruby motif. The constituent functional units will be assembled (a) via ion pairing, (b) via coordinative bonds in heterobimetallic complexes or (c) via redox tuning of mixed-valent CrII/CrIII salts. To disentangle the interaction effects on a molecular level, we will employ suitable spectroscopic methods at variable temperature, including time-resolved spectroscopies as well as quantum chemical investigations (benchmarked DFT and post-Hartree–Fock methods) including an adequate representation of the ensemble. The ultimate aim of this project is an optical read-out of the iron(II) HS/LS population with high contrast using different read-out channels, namely quantum yield F, lifetime t and wavelength l of the chromium(III) luminescence.

Project summary:

In the present project, we aim at a fundamental understanding of spin switching in polynuclear SCO complexes, including the influence of the environment. We explore intramolecular magnetic coupling and a possible coupling to a ferromagnetic substrate to improve switchability and to obtain a greater switching response. New dinuclear and trinuclear Fe(II) complexes are synthesised and analysed by X-ray absorption spectroscopy and Fourier transform THz electron paramagnetic resonance spectroscopy. These investigations are accompanied and supported by high-level quantum chemical calculations.