Erlangen 2022 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
MO: Fachverband Molekülphysik
MO 9: Femtosecond Spectroscopy II
MO 9.6: Talk
Wednesday, March 16, 2022, 11:45–12:00, MO-H5
Ultrafast Dynamics of Xanthine Derivatives and their Use in a Nickel-Catalysed Cross-Coupling Reaction — •Thomas Rittner1, Rafael E. Rodríguez-Lugo2, Karina Heilmeier1, Svenja Wortmann1, Simon Dietzmann2, Robert Wolf2, and Patrick Nuernberger1 — 1Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg — 2Institut für Anorganische Chemie, Universität Regensburg, 93040 Regensburg
Carbon-carbon and carbon-heteroatom cross-coupling is of high relevance in organic synthesis. In recent years, photo-induced nickel dual-catalysis has been successfully implemented for such bond-forming reactions under exceptionally mild conditions, albeit usually expensive precious metal containing photosensitizers are required [1]. We circumvent this issue with newly developed Xanthine-based ligands.
We employ both stationary and time-resolved absorption and emission spectroscopy to unveil the mechanism of this newly developed catalytic system. Spectral properties and dynamics of the ligands, of the reaction mixture, and of a model complex are juxtaposed. The coordination of the Xanthine ligands to Ni(II) is found to be rather weak. The lack of spectral overlap of ligand absorption and light source, as well as the ligand’s short excited-state lifetime queries the direct involvement of the ligand in the primary photostep. We thus aim at identifying alternative mechanisms for the photocatalytic process. Additionally, a competitive photoisomerization in the Xanthine ligand may occur.
[1] C. Zhu et al., Angew. Chem. Int. Ed. 2021, 60, 17810.