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MO: Fachverband Molekülphysik
MO 8: Poster 1
MO 8.23: Poster
Dienstag, 15. März 2022, 16:30–18:30, P
Exploring the photophysics and chemistry of triarylamin with regard to the applicability in photocatalysis — •Josephine Babel, Patrick Nuernberger, and Roger Jan Kutta — Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Germany
Triarylamines Ph3N generally possess a reversible one-electron oxidation behaviour, allowing the formation of its stable radical cation (Ph3N•+). This makes them particularly attractive for photocatalytic oxidiations of substrates with extreme high oxidation potentials via oxidative consecutive photoinduced electron transfer (con-PET) accumulating two photons of light.
Here, we characterize the photophysics and chemistry of Ph3N and Ph3N•+ in the presence and absence of molecular oxygen via transient absorption from fs to ms in the UV-visible spectral range. Starting from Ph3N, we find Ph3N•+ formation upon illumination via a bimolecular reaction of two molecules either each in a triplet state or one in a triplet and the other in the groundstate. The excited state of Ph3N•+ is, with a decay in the sub-100 ps, shorter than typical diffusion times for bimolecular reactions, which imposes limitations in terms of photocatalytic applicability. Considering also the determined photoinstability due to intra- and intermolecular photoconversion of Ph3N, photocatalytic reactions must outcompete the intrinsic deactivation pathways for applications of photocatalytic con-PET type. Approaches to overcome these limitations such as pre-assembly or enhanced intersystem crossing within the photocatalyst will be discussed.