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: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 449447254

• Final Report Year: 2024

Final Report Abstract

The integration of photocatalysis with transition metal catalysis leverages visible light as a benign energy source for conducting cross-coupling reactions, which stand as pivotal transformations in the synthetic chemist's repertoire. In these state-of-the-art approaches in crosscoupling catalysis, the photocatalyst harnesses visible light, converting photon energy into chemical potential that the metal catalysts subsequently utilize to forge new chemical bonds between two reactants. Typically, both the photo- and metal catalysts are dissolved in the reaction mixture, rendering the recycling of these invaluable catalysts nearly impossible. This research endeavour aimed to pioneer the development of bifunctional catalysts, by combining the functionalities of both the photo- and transition metal catalysts within a singular, heterogeneous material. Drawing inspiration from dye-sensitized solar cells (DSSCs), a modular design was targeted: We proposed that metal oxide semiconductors functionalized with a sensitizer to facilitate visible light absorption can be additionally decorated with a transition metal catalyst. Under the auspices of this DFG project, my team successfully realized this concept. We developed and studied several bifunctional catalyst materials that indeed showed catalytic activity in mediating carbon–heteroatom and carbon–carbon bond formations under both high-energy (blue) and low-energy (red) light conditions. These findings underscored the viability of our approach, but we also identified significant limitations regarding the applicability of our approach. As such, these findings served as a cornerstone for our ongoing endeavours in the realm of photoactive (macro)ligands for light-driven transition metal catalysis.

Publications

• Carbon dot/TiO2nanocomposites as photocatalysts for metallaphotocatalytic carbon–heteroatom cross-couplings. Green Chemistry, 23(12), 4524-4530.
  Zhao, Zhouxiang; Reischauer, Susanne; Pieber, Bartholomäus & Delbianco, Martina
  
• Recyclable, Bifunctional Metallaphotocatalysts for C−S Cross‐Coupling Reactions. ChemPhotoChem, 5(8), 716-720.
  Reischauer, Susanne & Pieber, Bartholomäus
  
• Heterogeneous metallaphotoredox catalysis in a continuous-flow packed-bed reactor. Beilstein Journal of Organic Chemistry, 18, 1123-1130.
  Hsu, Wei-Hsin; Reischauer, Susanne; Seeberger, Peter H.; Pieber, Bartholomäus & Cambié, Dario
  
• Intraligand Charge Transfer Enables Visible‐Light‐Mediated Nickel‐Catalyzed Cross‐Coupling Reactions**. Angewandte Chemie, 134(46).
  Cavedon, Cristian; Gisbertz, Sebastian; Reischauer, Susanne; Vogl, Sarah; Sperlich, Eric; Burke, John H.; Wallick, Rachel F.; Schrottke, Stefanie; Hsu, Wei‐Hsin; Anghileri, Lucia; Pfeifer, Yannik; Richter, Noah; Teutloff, Christian; Müller‐Werkmeister, Henrike; Cambié, Dario; Seeberger, Peter H.; Vura‐Weis, Josh; van der Veen, Renske M.; Thomas, Arne & Pieber, Bartholomäus
  
• Modulating the Surface and Photophysical Properties of Carbon Dots to Access Colloidal Photocatalysts for Cross-Couplings. ACS Catalysis, 12(22), 13831-13837.
  Zhao, Zhouxiang; Pieber, Bartholomäus & Delbianco, Martina
  
• A photoactive nickel complex provides evidence for a general Ni(I)/Ni(III) paradigm in cross-coupling catalysis.
  Anghileri, Lucia; Baunis, Haralds; Bena, Aleksander R.; Giannoudis, Christos; Burke, John H.; Reischauer, Susanne; Merschjann, Christoph; Wallik, Rachel F.; Simionato, Gianluca; Kovalenko, Sergey; Dell’Amico, Luca; van der Veen, Renske M. & Pieber, Bartholomäus