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.