Photo-Manganese: Luminescence, Photo-Redox and Spin-State Trapping

• Applicant: Professorin Dr. Katja Heinze
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 583386910

Recent advancements in the field of light-matter interactions have showcased the unique photophysics and photochemistry of manganese complexes with d3, d5 and d6 electron configurations in strong ligand fields. In our previous work, we demonstrated extremely long excited state lifetimes for ligand-to-metal charge transfer (LMCT), metal-to-ligand charge transfer (MLCT) and high-spin excited states for d3-manganese(IV), d6-manganese(I) and d5-manganese(II) complexes with suitable ligand fields, respectively. These long lifetimes recommend this type of complexes for applications in photoredox catalysis, energy transformation and information storage. However, synthetic chemistry, photophysics and photochemistry of manganese complexes in strong ligand fields are heavily underdeveloped with only very few examples documented, especially when compared to the respective iron counterparts. This proposal aims to fill this knowledge gap and systematically investigates the design, photophysics and photochemistry of manganese complexes with d3 – d6 electron configurations in strong ligand fields. We aim to construct manganese complexes informed by prior computational screening of suitable carbene-containing ligands for the various manganese oxidations states. Specifically, we will screen for (relative) redox potentials, excited state energies and excited state distortions. The computational findings will be crucial to develop strongly photo-oxidizing d3-manganese(IV) LMCT photocatalysts, strongly photo-reducing low-spin d6-manganese(I) MLCT photocatalysts, low-spin d4-manganese(III) spin-crossover (SCO) complexes and low-spin d5-manganese(II) complexes capable of undergoing light-induced excited spin-state trapping (LIESST) or displaying bright photoluminescence (PL). Through this work, we will broaden the scope and range of photoactive transition metal complexes based on Earth-abundant elements, improving the state-of-the-art of transition metal photophysics and photochemistry and methodology development, which paves the way for potential large-scale applications in photocatalysis, energy conversion and information storage.

• DFG Programme: Research Grants