Conjugated Microporous Polymers with Rose Bengal Dye for Highly Efficient Heterogeneous Organo-Photocatalysis

Rose Bengal dye has been successfully integrated into the skeleton of a conjugated microporous polymer via palladium-catalyzed Sonogashira-Hagihara cross-coupling polycondensation. These polymers are stable in various solvents, including concentrated hydrochloric acid, and are thermally stable. The resulting polymers show substantial porosity and are highly active for heterogeneous photocatalytic aza-Henry reactions at room temperature for a wide range of substrates. Moreover, this noble-metal-free photocatalyst shows robust recycling capability with good retention of photoactivity over 10 cycles without significant loss of conversion (<10%). These data show that dye-functionalized conjugated microporous polymers are stable, highly active, and reusable noble-metal-free heterogeneous photo-organocatalysts.