Porous, Crystalline, Covalent Organic Frameworks

Abstract

Covalent organic frameworks (COFs) have been designed and successfully synthesized by condensation reactions of phenyl diboronic acid {C 6 H 4 [B(OH) 2 ] 2 } and hexahydroxytriphenylene [C 18 H 6 (OH) 6 ]. Powder x-ray diffraction studies of the highly crystalline products (C 3 H 2 BO) 6 ·(C 9 H 12 ) 1 (COF-1) and C 9 H 4 BO 2 (COF-5) revealed expanded porous graphitic layers that are either staggered (COF-1, P 6 3 / mmc ) or eclipsed (COF-5, P 6/ mmm ). Their crystal structures are entirely held by strong bonds between B, C, and O atoms to form rigid porous architectures with pore sizes ranging from 7 to 27 angstroms. COF-1 and COF-5 exhibit high thermal stability (to temperatures up to 500° to 600°C), permanent porosity, and high surface areas (711 and 1590 square meters per gram, respectively).