연세대학교 이과대학 화학과

일시: 2026년 3월 19일 (목) 오후 5시

장소: 과학관 B133호

초록: 

We report the design of a cyanoarene-based photocatalytic system optimized for halogen atom transfer (XAT)-induced radical reactions. Our investigation reveals a competition between the productive catalytic cycle and photocatalyst (PC) degradation, the degradation becomes dominant when using unactivated alkyl halides. Recognizing that PC degradation limits XAT efficiency, we began our investigation to redirect these pathways toward desirable outcomes.  

Contrary to the conventional view of catalyst degradation as a deleterious process, we report a strategic manipulation of these pathways to enhance catalytic performance. In our studies of XAT-induced dehalogenation, we developed a series of cyanoarene-based pre-catalysts designed to undergo rapid, intentional degradation into more active forms. These in-situ evolved species exhibit significantly enhanced reducing ability in their radical anion state, which facilitates more efficient PC regeneration and robust XAT reactivity. Furthermore, we investigated the impact of the PC degradation behavior in Giese-type carbon-carbon bond-forming reactions. To ensure preferred catalysis over non-productive decomposition, we developed specialized amines that synergize with the highly reducing PCs and exhibit improved XAT selectivity through their corresponding a-amino radical intermediates. This work provides a new perspective on catalyst stability, demonstrating that the degradation of a photocatalyst, when properly tailored, can serve as a productive gateway to superior catalytic activity.