). There is essentially no change in the absorption profiles of DiICztBu4, DiICzMes4, and DiICztBuCz4 before and after irradiation, suggesting that any photodegradation of the PCs is not the cause for the low yields in this reaction but rather the too low triplet energy (Figure ). 4CzIPN and DiICztBuDPA4 are stable under the reaction conditions (Figure and e) and the 5% yield for 4CzIPN and the 0% yield for DiICztBuDPA4 can be attributed to each having a T1 energy that is effectively too low to enable the DET with any degree of efficiency. a (S)-verbenone (0.2 mmol) in DCM (0.1 M) with given PC loadings. Yields were determined by 1 H NMR spectroscopy using 1,3,5-trimethoxybenzene as the internal standard. b from ref. in CD3CN with hv = 415 nm after 3 h.