Defect porous organic frameworks (dPOFs) as a platform for chiral organocatalysis

Abstract

Abstract Porous organic frameworks (POFs) are emerging as an important class of porous materials. The absence of functional groups in POFs, however, renders them relatively nonspecific as porous materials for applications such as in heterogeneous chiral catalysis. Although pre- and post-synthetic modifications have been developed for the functionalization of POFs, the introduction of functional groups into POFs remains a great challenge. Herein we have advanced a facile and versatile strategy to uniformly incorporate targeted functional groups into defect porous organic frameworks (dPOFs) by one-pot copolymerization of low-connected functional and primitive multi-connected building blocks. Based on this strategy, four proline-functionalized dPOFs were readily synthesized and developed as new platforms for heterogeneous chiral organocatalysis. The as-prepared dPOFs show higher catalytic activity and superior enantioselectivity than that of their homogeneous counterpart l -proline in the catalytic direct aldol reaction between 4-nitrobenzaldehyde and acetone, and could be reused at least five times without significant loss of catalytic activity and enantioselectivity.