Fig. 6: Proposed mechanism for photocatalytic transformation of tetraphenylborate with 1.
From: Charge-transfer complexation of coordination cages for enhanced photochromism and photocatalysis
1 undergoes PET with BPh4− to produce BPh4• (I) and subsequent ET with O2 to produce O2•−. The intramolecular C-C coupling through 1,2-rearrangement in I leads to intermediate II, to which O2•− is added to give III. Biphenyl product is released from III, along with intramolecular ET to coordinated O2•− generating a peroxide intermediate IV. IV reacts with water to give V, which then undergoes B-to-O phenyl migration to give VI. Hydrolysis of VI produces phenol product and VII, the latter of which further undergoes oxidative hydroxylation in the presence of 1 to produce another equivalent of phenol.
