Rostock 2019 – scientific programme
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MO: Fachverband Molekülphysik
MO 3: Ultrafast Processes in Solution
MO 3.1: Invited Talk
Monday, March 11, 2019, 10:30–11:00, S HS 001 Biologie
Solvent-Specific Facets in the Ultrafast Photochemistry of Reactive Intermediates — Johannes Knorr1, Pandian Sokkar2, Svenja Wortmann1, Paolo Costa3, Niklas Gessner1, Julien Rowen3, Wolfram Sander3, Elsa Sanchez-Garcia2, and •Patrick Nuernberger1 — 1Physikalische Chemie II, Ruhr-Universität Bochum, 44780 Bochum — 2Computational Biochemistry, Universität Duisburg-Essen, 45141 Essen — 3Organische Chemie II, Ruhr-Universität Bochum, 44780 Bochum
Organic diazo compounds can release a nitrogen molecule upon photoexcitation, yielding very reactive species that will further pursue different reaction pathways on an ultrafast time scale. Among those pathways are rearrangement, intersystem crossing, intermolecular proton uptake, or complexation with a solvent molecule, giving rise to variable product distributions. The underlying processes strongly depend on the solvent environment and are accompanied by processes like solvation, vibrational cooling, and ion separation.
We will present an overview of recent femtosecond studies on diazo precursors excited in protic and aprotic solvents as well as in binary solvent mixtures. In combination with multiscale molecular dynamics simulations, we elucidate the reactivity of nascent intermediate carbenes and carbocations and the remarkable sensitivity to hydrogen-bonding among adjacent solvent molecules which take the role of key abettors rather than bystanders for the fate of the reactive intermediate. Variation of solvent mixing ratios thus provides a means to control the time scales and also the pursued pathways of the reaction.