Photoredox-active

Efforts have been made to reproduce these characteristics in model systems, and molecules with the core structures already described have been prepared. Though none as yet has shown any photoredox activity the 270 pm distance has been shown to be consistent with (/u-oxo)2 bridges and 330 pm with /u-oxo or /u,-oxo-/u-carboxylate bridges. Several mechanistic proposals have been made incorporating these features. 

Table 5.6 Properties of three typical photoredox-active molecules. bpy denotes 2,2 bipyridine, TMPP is tetra N-methylpyridine porphyrin Amax is the wavelength of the absorption maximum, e is the extinction coefficient at Amax, cpT is the quantum yield of the formation of the excited triplet state, r0 is its lifetime, and E0 are standard redox potentials...

Some properties of three typical photoredox-active dyes are summarized in Table 5.6. The most important photogalvanic system is based on the photoredox reaction of thionine with Fe2+. It was first studied by E. Rabinowitch in 1940 and recently optimized by J. W. Albery et ah The structural formula of thionine, Thi+ and its reduction products (Sem+, Leu2+) are as follows ... 

Multicomponent assemblies in which a photoredox-active metal-polypyridine unit is combined with electron acceptors and/or donors show very rich photo-induced electron transfer reactivity [38]. Such species are often called molecular dyads (triads, tetrads. ..). Electron transfer usually occurs from an excited metal-polypyridine unit M to an attached acceptor ... 

TMU2H)3 PMoi2O40 TMUb TMU-derived oxidation products Reduced POM not re-oxidized TMUb Initial report of organic substrate donor-POM acceptor photoredox-active complex 79... 

Mn 12 Enzymes (phosphatase, mitochondrial superoxide dismutase, glycosyl transferase) photoredox activity in Photosystem II (see equation 21.53 and discussion)... 

Experiment 5-10 Covalent Binding of a 5,10,15,20-Tetraphenylpor-phyrin Derivative at Polystyrene for Polymer 53 and Photoredox Activity (Section 5.2.1) [132-135]... 

For a very recent example about the combination of photoredox activation and anion binding catalysis, see G. Bergonzini,... 

Schroot R, Friebe C, Altuntas E, Crotty S, Jager M, Schubert US (2013) Nitroxide-mediated polymerization of styrenic triarylamines and chain-end functionalization with a ruthenium complex toward tailored photoredox-active architectures. Macromolecules 46 2039-2048... 

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