Visible-light photoinduced electron transfer (Vis-PET) is highly important for optoelectronic devices and photoredox catalysis. Herein, we propose a supramolecular strategy to promote the Vis-PET process by charge transfer (CT) interactions. As a proof of concept, a molecular system containing 1,5-alkoxy-substituted naphthalene and viologen moieties was designed to form a CT complex in water. The HOMO/LUMO energy gap was lowered by CT interaction, which turned on the Vis-PET process to generate viologen radical cations. Moreover, when CT interaction was enhanced by cucurbit[8]uril, the efficiency of the Vis-PET process was further promoted and the required irradiation wavelength could be further red-shifted by 100 nm. The Vis-PET system exhibited an improved activity of photocatalysis, as supported by the fast photoreduction of Cytochrome c. This study represents a facile supramolecular way to fabricate radicals with maintained activity under mild conditions, which holds potential to enrich the scope of visible-light photoredox catalysis by the rational utilization of CT systems.
Keywords: charge transfer interaction; energy levels; host−guest interaction; photoinduced electron transfer; photoredox catalysis.