Ultrasmall CsPbBr3 Nanocrystals as a Recyclable Heterogeneous Photocatalyst in 100% E- and Anti-Markovnikov Sulfinylsulfonation of Terminal Alkynes.

ABSTRACT

The precise synthesis of ultrasmall, monodisperse CsPbBr3 nanocrystals is crucial due to their enhanced photophysical properties resulting from strong quantum confinement effects. Traditional methods struggle with size control, complicating synthesis. Although CsPbBr3 nanocrystals find applications in LEDs and photovoltaics, their use in photocatalysis for organic reactions remains limited. Our study introduces ultrasmall TBIA-CsPbBr3 nanocrystals (∼5.6 nm), synthesized via a three-precursor hot injection method using tribromoisocyanuric acid (TBIA) as a bromine precursor for the first time. These nanocrystals exhibit a near-unity photoluminescence quantum yield (PLQY) of 0.99 and an elevated oxidation potential of +1.80 V. We demonstrate their efficacy as recyclable heterogeneous photocatalysts in a one-pot, 100% E-selective, anti-Markovnikov sulfinylsulfonation of terminal alkynes under visible light, achieving a high product conversion rate (PCR) of 62,500 µmol g-1 h-1 and recyclability for up to five cycles. Density functional theory (DFT) calculations support the exclusive formation of the E-isomer. TBIA-CsPbBr3 outperforms other CsPbBr3 perovskites in photocatalysis, with superior efficiency attributed to their extended excited-state lifetime and higher surface area, which accelerates the organic transformation process.