Polyhedral oligomeric silsesquioxane difluoroboron complexes as cooperative octo-site catalysts for the photooxidation of sulfides to sulfoxides

Abstract

The incorporation of difluoroboron into the side arms of polyhedral oligomeric silsesquioxanes (POSSs) opens up new possibilities for the construction of metal-free photocatalysts with tailored properties. Herein, we report the design and synthesis of novel difluoroboron complexes of POSSs (POSS-tert-BF₂, POSS-sal-BF₂ and POSS-npht-BF₂) derived from imine-functionalized POSSs, which were utilized as efficient photocatalysts. The complexes demonstrated exceptional photocatalytic performance in the aerobic oxidation of sulfides to sulfoxides, significantly outperforming their silsesquioxane-free counterparts. POSS-tert-BF₂ demonstrated a high singlet oxygen quantum yield of 48%. This study highlights the feasibility of intramolecular cooperative activity in catalytic reactions and identifies key factors influencing its effectiveness. Furthermore, it underscores the potential of POSS as a versatile building block for the development of advanced photocatalytic materials.