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Stepwise Photoinduced Electron Transfer in a Tetrathiafulvalene-Phenothiazine-Ruthenium Triad

Skaisgirski, Michael and Larsen, Christopher B. and Kerzig, Christoph and Wenger, Oliver S.. (2019) Stepwise Photoinduced Electron Transfer in a Tetrathiafulvalene-Phenothiazine-Ruthenium Triad. European Journal of Inorganic Chemistry (39-40). pp. 4256-4262.

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Official URL: https://edoc.unibas.ch/73101/

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Abstract

A molecular triad comprising a [Ru(bpy)3]2+ (bpy = 2,2′‐bipyridine) photosensitizer, a primary phenothiazine (PTZ) donor and a secondary (extended) tetrathiafulvalene (exTTF) donor was synthesized and explored by UV/Vis transient absorption spectroscopy. Initial photoinduced electron transfer from PTZ to the 3MLCT‐excited [Ru(bpy)3]2+ occurs within less than 60 ps, and subsequently PTZ is regenerated by electron transfer from exTTF with a time constant of 300 ps. The resulting photoproduct comprising exTTF·+ and [Ru(bpy)3]+ has a lifetime of 6100 ps in de‐aerated CH3CN at room temperature. Additional one‐ and two‐pulse laser flash photolysis studies of the triad were performed in the presence of excess methyl viologen (MV2+), to explore the possibility of light‐driven charge accumulation on exTTF. MV2+ clearly oxidized [Ru(bpy)3]+ and thereby re‐instated ground‐state [Ru(bpy)3]2+ in triads in which exTTF had been oxidized to exTTF·+, but further excitation of the solution containing the exTTF·+‐PTZ‐[Ru(bpy)3]2+ photoproduct did not provide evidence for exTTF2+. Nevertheless, it seems that the design principle of a covalent donor‐donor‐sensitizer triad (as opposed to simpler donor‐sensitizer dyads) is beneficial for light‐driven accumulation of oxidation equivalents. These investigations are relevant in the greater context of multi‐electron photoredox chemistry and artificial photosynthesis.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Wenger)
UniBasel Contributors:Wenger, Oliver and Skaisgirski, Michael and Larsen, Christopher Bryan and Kerzig, Christoph
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Wiley
ISSN:1434-1948
e-ISSN:1099-0682
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Identification Number:
Last Modified:18 Dec 2019 09:00
Deposited On:18 Dec 2019 09:00

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