Designer photo-catalysts and multi-electron processes based on redox-active hybrid molecules and their application in synthesis and activation of small molecules

• Applicant: Professor Dr. Max Martin Hansmann
• Subject Area: Organic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 429658300

The development of organic redox-active molecules is of high relevance in the areas of energy storage, electronics and digital data storage. Besides, organic photo catalysts have found an increasing use as modern tools in organic synthesis. The main concept of traditional photo-catalysis is based on two stable redox states, one of them and in rare cases both being excited by visible light. In order to develop highly stereo- and chemo-selective transformations outside of the so far established redox scale new approaches are required. In order to address this aim, this project focusses on creating photo/redox cascades, which are based on combining the concepts of multiple redox-active molecules (redox chemistry) with selective excitation by light (photo chemistry). In consideration of the fact that, depending on the area of application, entire diverse requirements for the redox potentials of the photo-catalysts are necessary, there is an immense need for the rapid construction of custom-made catalyst systems. This demand will be targeted by the research proposal and tested extensively in terms of preparative applicability. Emphasis will be put on the structure based chemical rationale of the catalyst and its redox- and photo-chemistry. Hence, we are postulating novel redox-active photo-catalysts, structurally outside of the previously established spectrum, which are quickly assembled as hybrids in a modular fashion. As a result of their fine-tunable redox potentials, the here postulated hybrids can reach a significantly broadened redox scale which will be utilized in the strongly reducing (and enantioselective) photo catalysis. Therefore, photo-catalytic processes with high selectivity can be tailored, which might lead in the long run to the circumvention of protecting groups. In parallel projects, the individual paramagnetic components of the hybrids will be studied in detail and additionally the concept of hybrid molecules will be applied to multi electron donors. The latter ones will enable the analysis of organic mixed-valence compounds in addition to their potential applications in the area of energy storage. Furthermore, a linkage between the concept of organic hybrid molecules and the area of coordination chemistry is investigated. This approach will lead to readily available redox active and photo-chemically excitable ligand frameworks. Furthermore, we are postulating a new concept for the activation of small molecules by photo chemically generated radical pairs. Such radical pairs should allow through SOMO/SOMO combinations the homolytic cleavage of small molecules therefore enabling a fundamentally new bond cleavage process and entry into catalytic reactions respectively.

• DFG Programme: Independent Junior Research Groups