Enhancing the Rate of Quantum-Dot-Photocatalyzed Carbon-Carbon Coupling by Tuning the Composition of the Dot's Ligand Shell

This Communication describes the photoredox catalysis of a C-C coupling reaction between 1-phenylpyrrolidine (PhPyr) and phenyl trans-styryl sulfone by visible-light-absorbing colloidal CdS quantum dots (QDs), without a sacrificial oxidant or reductant, and without a co-catalyst. Simple kinetic analysis reveals that photo-oxidation of PhPyr by the QDs is the rate-limiting step. Disordering of the ligand shell of the QDs by creating mixed monolayers of oleate and octylphosphonate increases the initial rate of the reaction by a factor of 2.3, and the energy efficiency (mol product/joule of incident photons) of the reaction by a factor of 1.6, by facilitating the hole-transfer step.