Figure 1.
Mechanistic studies (A) Reactions studied by TA and luminescence spectroscopies. (B) TA data collected at 390 nm with 10 mM DCB, 40 μM Ir(ppy)3, and increasing concentrations of 1m. The laser flash leads to rapid oxidation of the Ir(ppy)3+, yielding a large negative absorbance change because the Ir(ppy)3+ species has a smaller ε390 than Ir(ppy)3 (Figure S3). 1m oxidation by Ir(ppy)3+ is observed as a return in the absorbance at 390 nm as Ir(ppy)3+ is reduced to Ir(ppy)3. Residual DCB·− absorbance was observed at higher concentrations of 1m. (C) TA spectroscopy at 346 nm to monitor DCB·− reactivity. (D) Proposed photoredox cycle.