Erlangen 2022 – scientific programme
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MO: Fachverband Molekülphysik
MO 14: Photochemistry II
MO 14.4: Talk
Wednesday, March 16, 2022, 15:15–15:30, MO-H6
Photochemistry of the Benzaldehyde-BCl3 Complex — •Martin Peschel1, Piotr Kabacinski2, Daniel Schwinger3, Erling Thyrhaug4, Thomas Knoll1, Giulio Cerullo2, Thorsten Bach3, Jürgen Hauer4, and Regina de Vivie-Riedle1 — 1Department Chemie, Ludwig-Maximilians-Universität München — 2IFN-CNR and Dipartimento di Fisica, Politecnico di Milano — 3Department of Chemistry and Catalysis Research Center (CRC), Technische Universität München — 4Professur für Dynamische Spektroskopien, Fakultät für Chemie, Technische Universität München
The excited state properties of α,β-enones can be altered by complexation with a Lewis acid to enable otherwise unaccesible photochemical transformations.[1] After excitation, α,β-enones relax to a triplet state from which subsequent reactions can occur. This ππ* triplet is stabilized by interaction with a Lewis acid and studies using UV/Vis transient absorption spectroscopy and quantum chemical calculations show that its formation only takes a few picoseconds.[2] We expected this behavior to also occur in the aromatic α,β-enone benzaldehyde when interacting with the Lewis acid BCl3. Instead, non-adiabatic dynamics calculations showed ultrafast dissociation of a chlorine atom. The resulting benzyl radical could be identified in a theory-guided UV/Vis ultrafast transient absorption experiment and was found to be surprisingly long lived. This led to the discovery of a novel chemical reaction of benzaldehyde which uses the radical chemistry of chlorine.
[1] Angew. Chem. Int. Ed. 2018, 57, 14338-14349.
[2] Angew. Chem. Int. Ed. 2021, 60, 10155-10163.