Joseph R. Hunt

Three-dimensional covalent organic frameworks (3D COFs) were synthesized by targeting two nets based on triangular and tetrahedral nodes: ctn and bor. The respective 3D COFs were synthesized as crystalline solids by condensation reactions of tetrahedral tetra(4-dihydroxyborylphenyl) methane or tetra(4-dihydroxyborylphenyl)silane and by co-condensation of triangular 2,3,6,7,10,11-hexahydroxytriphenylene. Because these materials are entirely constructed from strong covalent bonds (C-C, C-O, C-B, and B-O), they have high thermal stabilities (400 degrees to 500 degrees C), and they also have high surface areas (3472 and 4210 square meters per gram for COF-102 and COF-103, respectively) and extremely low densities (0.17 grams per cubic centimeter).

A new crystalline porous three-dimensional covalent organic framework, termed COF-300, has been synthesized and structurally characterized. Tetrahedral tetra-(4-anilyl)-methane and linear terephthaldehyde building blocks were condensed to form imine linkages in a material whose X-ray crystal structure shows five independent diamond frameworks. Despite the interpenetration, the structure has pores of 7.2 A diameter. Thus, COF-300 shows thermal stability up to 490 degrees C and permanent porosity with a surface area of 1360 m(2) g(-1).

Three new crystalline microporous and mesoporous 2D covalent organic frameworks termed COF-6, -8, and -10 from boronic acid building blocks and 2,3,6,7,10,11-hexahydroxytriphenylene have been synthesized and structurally characterized. These materials constructed of C2O2B rings form eclipsed layered structures with pore sizes ranging from 6.4 to 34.1 Å and are found to have high thermal stability, low density, and high porosity as indicated by the surface areas of 980, 1400, and 2080 m2 g-1 for COF-6, -8, and -10, respectively. The control of pore size and structure demonstrates the effectiveness of reticular chemistry methods toward materials design.