CsPbBr3 in the Activation of the C-Br Bond of CBrX3 (X = Cl, Br) under Sunlight

A newly synthesized green-fluorescent, orthorhombic, bromide-rich, perovskite nanocrystal (phi 0.93, tau 12.5 ns, Eox = +1.6 V) obtained from an unprecedented bromide precursor dibromoisocyanuric acid was found to be an excellent visible-light (sunlight or blue-light-emitting diode (LED)) photocatalyst toward the synthesis of gem-dihaloenones for the first time. The photoactivated CsPbBr3 catalyzed the homolytic cleavage of CBrX3 (X = Cl, Br) to generate the center dot CX3 radical, which underwent cascaded C-C cross-coupling with terminal alkynes into the corresponding gem-dihaloenones. Radical-trapping experiments and luminescence-quenching studies helped establish a single electron-transfer (SET) mechanism. Interestingly, other highly stable CsPbBr3 NCs, obtained from N-bromosuccinimide (NBS) and dibromohydantoin (DBHT) precursors, are unable to carry out these transformations. These results not only enrich the CsPbBr3 synthetic methodology but also encourage the research community to develop efficient and cost-effective photocatalytic materials.