Porous Aromatic Frameworks for Size-Selective Halogenation of Aryl Compounds.

Organic halides are vitally important chemical precursors or intermediates in the fields of agrochemical synthesis, molecular recognition, and material science. However, it is difficult to selectively synthesize these compounds due to the multiple reactive sites in aryl fragments. In this work, we prepared the first fully fluorinated porous aromatic framework (PAF). Its -C-F bond and hierarchical porosity have great benefits for PAF functionalization. After being decorated with different cyclodextrins (CDs), CD-PAF materials can incorporate diverse aryl compounds to protect their ortho sites from being attacked to produce para-substituted molecules. This selectivity obviously increased with a decrease in the substrate size (from 0.97 to 0.41 nm). In addition, the CD-PAFs can undergo long-term use in both chlorination and bromination.