Freiburg 2024 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 21: Ultrafast Dynamics II
MO 21.8: Vortrag
Donnerstag, 14. März 2024, 16:15–16:30, HS 3044
Exciton Dynamics Pathways in a Merocyanine Dye-based Artificial Light-Harvesting Antenna — •Rebecca Fröhlich1, Ajay Jayachandran1, Alexander Schulz2, Matthias Stolte3, Frank Würthner2,3, and Tobias Brixner1 — 1Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg — 2Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg — 3Center for Nanosystems Chemistry (CNC), Universität Würzburg, Theodor-Boveri-Weg, 97074 Würzburg
Natural photosynthesis relies on light-harvesting systems with precisely arranged chromophore structures. We investigate the exciton dynamics in an artifical light-harvesting antenna comprised of four dipolar merocyanine chromophores, covering a broad range of the visible spectrum. The molecule shows a solvent-depending folding-induced fluorescence enhancement previously described on a trimer structure [1]. Irrespective of excitation wavelength, the molecule fluoresces only from the lowest excitonic state, which is a sign for efficient energy transfer in the tetramer. To investigate the exciton transfer pathways we performed transient absorption measurements with selective excitation of the exciton bands and coherent 2D electronic spectroscopy. The data show downwards energy transfer via parallel energy transfer pathways. A solvent comparison reveals that the energy transfer times depend on the folding degree of the supramolecular structure.
[1] A. Schulz and F. Würthner, Angew. Chem. Int. Ed., 61, e202114667 (2022)
Keywords: ultrafast; transient absorption; 2D spectroscopy; exciton; merocyanine