Supramolecular confinement effect enabling light-harvesting system for photocatalytic α-oxyamination reaction

The supramolecular Förster resonance energy transfer (FRET) is seen as a promising approach for organic photocatalysis using dyes as catalysts, because it combines the high efficiency of energy transfer with the dynamic responsiveness based on non-covalent interactions. Here we propose a supramolecular FRET photocatalysis strategy for α-oxyamination reaction based on supramolecular confinement effect. The well-designed benzothiadiazole-based cationic monomer as energy donor and the dyes of Nile Red as acceptor are doped into the amphiphilic surfactants of sodium dodecyl sulfate (SDS). Benefitting from the supramolecular confinement space provided by SDS in aqueous environment, the FRET process between the monomer and Nile Red is effectively achieved (exciton migration rate: 3.99 × 10¹⁴ L mol^‒1 s^‒1). On this basis, the supramolecular FRET system is used as an efficient energy source to catalyze α-oxyamination reactions between a series of 1,3-dicarbonyl compounds and 2,2,6,6-tetramethylpiperidine-1-oxyl under white LED light, showing a yield as high as 94 % and a turnover frequency value of 3.92 h^‒1. This photocatalytic result shows a great enhancement compared to that of Nile Red alone.