Abstract

To achieve artificial photosynthesis it is necessary to couple the single-electron event of photoinduced charge separation with the multi-electron reactions of fuel formation and water splitting. Therefore, several rounds of light-induced charge separation are required to accumulate enough redox equivalents at the catalytic sites for the target chemistry to occur, without any sacrificial donors or acceptors other than the catalytic substrates. Herein, we discuss the challenges of such accumulative electron transfer in molecular systems. We present a series of closely related systems base on a Ru(II)-polypyridine photosensitizer with appended triaryl-amine or oligo-triaryl-amine donors, linked to nanoporous TiO2 as the acceptor. One of the systems, based on dye 4, shows efficient accumulative electron transfer in high overall yield resulting in the formation of a two-electron charge-separated state upon successive excitation by two photons. In contrast, the other systems do not show accumulative electron transfer because of different competing reactions. This illustrates the difficulties in designing successful systems for this still largely unexplored type of reaction scheme.

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Authors

Karlsson S, Boixel J, Pellegrin Y, Blart E, Becker HC, Odobel F, Hammarström L

Institution

Department of Photochemistry and Molecular Science, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden.

Source

Faraday discussions 155: 2012 pg 233-52; discussion 297-308

MeSH

Chlorophyll
Coordination Complexes
Electron Transport
Electrons
Kinetics
Light
Oxidation-Reduction
Oxygen
Photochemistry
Photons
Photosensitizing Agents
Photosynthesis
Ruthenium
Static Electricity
Titanium
Water

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

22470977