Metal–Organic Framework-Encapsulated Anthraquinone for Efficient Photocatalytic Hydrogen Atom Transfer

Anthraquinone (AQ) as an effective hydrogen atom transfer catalyst was limited in photocatalysis application due to the dimerization of reduced AQ. Sr–NDI@AQ, encapsulating AQ into the channel of Sr–NDI, paved a new way for solving the problem of dimerization of reduced AQ and improving the catalytic efficiency owing to the fast electron transfer from reduced AQ to the ligand through host–guest interaction. The structure of Sr–NDI@AQ was determined by single-crystal X-ray diffraction, and the value for distance and torsion angle between the ligand and AQ was calculated. The photochemical and electrochemical properties for Sr–NDI@AQ were characterized through a series of experiments. The coupling reaction between aldehyde and phenyl vinyl sulfone and photoacetalization reaction were carried out, displaying the improving catalytic efficiency of Sr–NDI@AQ compared to Sr–NDI and AQ. The reaction mechanisms were proposed through radical capture and electron paramagnetic resonance experiments.