Extended Data Fig. 2: Mechanism of the TFU photoredox catalysed Heck coupling of polysubstituted ethylenes.
a, Transient absorption spectra of BOPHY (0.001 mM) and DPA (1 mM) in N2 ACN/DMA (5/1 v/v) solution (λexc = 485 nm). b, Proposed photocatalytic mechanism of the Mizoroki–Heck coupling reaction between aryl bromides and polysubstituted alkenes. Cascade processes involving: ISC (intersystem crossing), TTEnT (triplet–triplet energy transfer), TFU (triplet fusion upconversion), SET (single electron transfer), C‒C bond formation and BET (back electron transfer). c, Delayed emission spectra of a mixture of BOPHY (0.1 mM) and DPA (1 mM) in bubbled (N2) ACN/DMA (5/1 v/v) after excitation (485 nm) with a pulsed laser in the absence (black) and in the presence of 4–bromoacetophenone (10 mM). d, Transient absorption spectrum recorded at 2 μs after the laser pulse of BOPHY (10−4 M) and DPA (10−3 M) in the presence of 4–bromoacetophenone (10−2 M) and 1,1-diphenylethylene (0.1 M) in 3 ml of N2 ACN/DMA (5/1 v/v); inset: decay kinetic monitored at 500 nm after 485 nm TAS.
