Heidelberg 2015 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 3: Femtosecond Spectroscopy 1
MO 3.2: Vortrag
Montag, 23. März 2015, 15:00–15:15, PH/HS1
Unraveling photochemical reaction pathways of diphenylcarbene in solvent mixtures — •Johannes Knorr1, Sebastian Schott2, Paolo Costa3, Wolfram Sander3, and Patrick Nuernberger1 — 1Physikalische Chemie II, Ruhr-Universität Bochum, 44780 Bochum — 2Institut für Physikalische und Theoretische Chemie, Am Hubland, Universität Würzburg, 97074 Würzburg — 3Organische Chemie II, Ruhr-Universität Bochum, 44780 Bochum
The primary reaction pathways of singlet diphenylcarbene (DPC) in the presence of a solvent can be summarized as an interplay of an intersystem crossing to the triplet state (e.g., in neat acetonitrile) and the formation of an ether product (in alcohols) which can either be formed by reaction with an alcohol in a concerted or stepwise manner or via a short-lived cation resulting from an ultrafast intermolecular proton-transfer reaction [1]. Recent studies on DPC embedded in argon matrices at low temperatures revealed dramatic changes in the reactivity when the carbene environment was modified by small amounts of methanol dopant molecules [2]. Connecting these findings with experiments in the liquid phase at room temperature, we employ femtosecond transient-absorption spectrocopy in the visible and ultraviolet regime to unravel the reactivity of DPC in solvent mixtures. Our studies corroborate that the dynamics are far from a linear combination of those observed in neat solvents, with the efficiency of different reaction channels varying significantly in dependence on the solvent mixing ratio.
J. Peon et al., J. Am. Chem. Soc. 2002, 124, 6428-6438
P. Costa and W. Sander, Angew. Chem. 2014, 53, 5122-5125