Fig. 1. Sensitization via the QD Photocatalyst and Mechanisms of Selectivity.

a, Sensitization of the triplet excited state of the substrate (T₁) through TT-EnT from CdSe QDs, and schematic representation of syn-HH or syn-HT selectivity of QDs. A proposed mechanism of the route to each diastereomer is shown in Supplementary Scheme 2. The best regioselectivity is achieved with molecules where the black circle represents an aromatic group (Ar). b, Chemical structures of the molecular sensitizers, and the mechanism of anti-HH preference of reactions driven by these molecules. c, Ground state absorption spectra of a mixture of CdSe QDs (radius = 1.4 nm) and 1 in THF, before and after three 48-h illumination cycles. The differences between spectra at λ < 450 nm are due to consumption of 1. d, Decay dynamics of the exciton in CdSe QDs mixed with 250 eq of 1 in THF, upon photoexcitation at 470 nm, monitored at three wavelengths: 480 nm (pure electron dynamics), 900 nm (primarily electron dynamics), and 1300 nm (primarily hole dynamics). Electrons and holes decay with a time constant of 130±30 ps (where the error bar is the standard error) in the presence of 1; this time constant is absent if 1 is not present, see Supplementary Fig. 1, Supplementary Table 3. The cyclic voltammetry of 1 and the band-edge energies of the CdSe QDs are in the SI, Supplementary Fig. 4. “OD” ≡ optical density.