Merging Photocatalysis with Transition Metal Catalysis in a Single, Modular Material

• Applicant: Professor Dr. Bartholomäus Pieber
• Subject Area: Organic Molecular Chemistry - Synthesis and Characterisation ; Synthesis and Properties of Functional Materials
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 449447254

The combination of photocatalysis with "conventional" catalysis (dual catalysis) enables sustainable synthesis by using visible light as energy source for important chemical transformations. Irradiation of a photocatalyst, typically a homogeneous ruthenium or iridium polypyridyl complex, results in an excited species that can transfer electrons or energy to a "conventional" catalyst to trigger a chemical reaction. Both catalysts are usually dissolved in the reaction mixture (homogeneous catalysis) and are not recycled. During the last two years, we could show that heterogeneous, recyclable semiconductors that absorb visible light can be used in combination with homogeneous nickel catalysts in a semi-heterogeneous dual catalysis approach. The aim of this project is the development of a heterogeneous catalyst that combines the function of both catalysts in a single material. The principle relies on metal oxide semiconductors, functionalized with a sensitizer to enable visible light harvesting and a conventional catalyst to access dual catalytic reactions. Linking the photocatalyst (dye functionalized semiconductor) and the "conventional" catalyst will not only give a single catalytic material for dual catalytic processes but also likely results in increased reaction rates as the permanent spatial proximity between both catalysts is proposed to enhance electron and energy transfer processes. The modular design will cover multiple dual catalysis strategies by using different metal catalysts and allows choosing from a plethora of organic dyes to select the absorption wavelength of the final catalyst system. This principle will enable us to design new syntheses and strategies for multistep transformations. This requires careful analysis of the heterogeneous catalysts and reaction mechanisms, which will be carried out during throughout this research project.

• DFG Programme: Research Grants
• International Connection: Austria