Photoexcitation of a molecular pentad in the presence of Sc3+ in de-aerated CH3 CN leads to a quinone dianion that is stable on the millisecond timescale. Light-driven electron accumulation on the quinone unit is sensitized by two Ru(bpy)32+ complexes in an intramolecular process, which relies on covalently attached triarylamine donors rather than on sacrificial reagents. Lewis acid-Lewis base interactions between Sc3+ and quinone dianion are responsible for the exceptionally long lifetime of this photoproduct. Our study of photoinduced multi-electron transfer is relevant in the greater context of solar energy conversion.
Keywords: donor-acceptor systems; electron transfer; energy conversion; photochemistry; time-resolved spectroscopy.
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