Mainz 2017 – scientific programme

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MO: Fachverband Molekülphysik

MO 12: Posters 2: Molecular Dynamics, Clusters, and High Resolution Spectroscopy

MO 12.8: Poster

Wednesday, March 8, 2017, 17:00–19:00, P OG1

Fluorescence dynamics and quantum yield measurements of a polycyclic tetrazolium compound in dependence on solvent viscosity — •Jan-Lucas Wree, Tom Bolze, and Patrick Nuernberger — Physikalische Chemie II, Ruhr-Universität Bochum, 44780 Bochum

The color change of tetrazolium salts that occurs during enzymatic reduction to formazans is exploited in applications like monitoring cell growth, since it can be conveniently measured in a quantitative fashion. Some particular tetrazolium compounds are known to further exhibit fluorescence, like the phenyl-benzo[c]tetrazolo-cinnolinium (PTC) which is investigated in this contribution.
We explore the fluorescence properties of PTC in alcoholic solvents whose viscosity span several orders of magnitude. Static measurements of absorption and fluorescence characteristics as well as of fluorescence quantum yields, measured against several reference compounds, are compared to the excited-state lifetimes obtained from time-correlated single-photon counting (TCSPC). The studies disclose that the emission characteristics vary but do not drastically change with solvent viscosity. This indicates that the emitting state is also deactivated by a competing, non-radiating reaction channel, but not by one that involves large intramolecular rotational motion, a process that would be strongly slowed down in more viscous solvents, as found for instance in molecular rotors or ultrafast C=C photoisomerization.