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Projects

Project area A: Photoinduced electron transfer catalysis

These are generally single-electron transfer processes (SET), which lead to radical cations, radical anions or radicals. Within the catalytic cycle, the redox process is closed by back electron transfer (BET) to or from the redox active chromophore. The light energy replaces reagents, like e.g. Bu3SnH or Ce(IV), and enables an efficient, sustainable organic synthesis. The stereoselectivity of the reaction is supposed to be controlled by the binding site of the substrate. Organic compounds, e.g. benzophenone, anorganic complexes or semiconductors are used as redoxactive chromophores; the binding of the substrate and the control of selectivity results from hydrogen bonds, reversible covalent or coordinative bonds. The redoxactive chromophore and the binding site of the substrate can act covalently linked or unlinked synergistically.

scheme

Principle of photoinduced transfer catalysis

A1. Stereoselective photocatalysts with high photostability
(Bach,* Dick, Riedle)
A2. Strongly reductive or oxidative photocatalysis by absorption of several photons
(König,* Jacobi von Wangelin, Dick, Riedle)
A3. Co-operative enamine-photoredox-catalysis, mechanistic studies and γ-functionalisation of aldehydes and ketones vio dienamine intermediates
(Gschwind,* Zeitler, Schütz)
A4. Photo-Catalytic Carbonylation Reactions
(Jacobi von Wangelin,* Bach, E. Lupton, Gschwind)
A5. Photocatalytic generation of C-radicals for the de-functionalisation and C-C-coupling reaction with Copper-catalysts
(Reiser,* E. Lupton, Dick, Riedle, Gschwind)
A6. The several faces of transition metal complexes in photo redox reactions
(Reiser,* E. Lupton, Dick, Riedle, Gschwind)

Project area B: Coupled photoredox reactions

In these systems, two two-electron transfer processes, one oxidative and one reductive half-reaction, are coupled through a photocatalyst. One of the half-reactions consumes, the other one provides electrons, while the overall process is endothermically or kinetically hindered and proceeds only by means of the absorbed light energy. As far as possible, two productive half-reactions should be used and sacrifice substrates ought to be avoided. Flavines or metal complexes serve as redoxactive chromophores; for the binding of the substrate metal complexes or organocatalysts are used.

scheme

Principle of coupled photoredox reactions

B1.Organic synthesis with Flavin photocatalysis
(König,* Riedle, Dick, Schütz, Wolf, Gschwind)
B2.Selective oxyfunctionalisation through coupled redox photocatalysis
(Wolf,* König, Dick, Gschwind )
B3.Coupling of NMR and UV spectroscopy, structure determination and demand interval in photocatalysis
(Gschwind,* Riedle, Schütz, Dick)
B4.Amplification of photocatalytic activity by statistic and dynamic electric and magnetic fields
(J. Lupton,* Vogelsang, König, Pfitzner, Gschwind, Dick)
B5.Heterogeneous photocatalytic reactions with visible light in organic synthesis
(König,* Pfitzner, Dick, Gschwind, J. Lupton)
B6.Reaction mechanisms of photocatalysts
(Dick,* Schütz, Riedle)