Exceptionally Long-Lived Photodriven Multi-Electron Storage without Sacrificial Reagents

Photoexcitation of a molecular pentad in the presence of Sc3+ in de-aerated CH3CN 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.