5,12-Dihydroquinoxalino[2,3-b] quinoxaline-based porous organic polymer as photocatalyst for visible-light-driven cross-coupling reactions

Porous organic polymers (POPs) have emerged as a novel porous photocatalyst that are prepared by the polymerization of various organic building blocks with different geometries and topologies. Herein, a novel 5,12-dihydroquinoxalino[2,3-b] quinoxaline-based POP was prepared by crosslinking with 5,12-diphenyl-5,12-dihydroquinoxalino [2,3-b] quinoxaline and 4,4′-bis(chloromethyl)-1,1′-biphenyl through FeCl₃-catalyzed Friedel–Crafts alkylation reaction. With the broad absorption in the visible light region, the 5,12-dihydroquinoxalino[2,3-b] quinoxaline-based POP efficiently catalyzed diverse photocatalytic C−X (X = N, P, C) cross-coupling reactions. The 5,12-dihydroquinoxalino[2,3-b] quinoxaline-based POP catalyst tolerated a diverse range of coupling partners to deliver the products in up to 90 % yields and could be readily recovered over five times by simple filtration without appreciable loss of catalytic activity, providing a promising platform for heterogeneous photocatalytic organic transformations. The successful application of this polymerization-enhanced photocatalysis strategy should guide an approach to the rational design of POP-type heterogeneous photocatalysts to address the dilemma of homogeneous photocatalysts in sustainability, stability, and recyclability.