Tetrahedral Building Blocks for the Synthesis of 3D Covalent Organic Frameworks (COFs) and Porous Polymers

　Three-dimensional (3D) covalent organic frameworks (COFs) and porous polymers are anticipated to be applicable for gas storage and separation, and as catalysts because of their high specific surface area and thermal stability. COFs are 2D or 3D covalently extended crystalline materials composed of light atoms.^1,2)
　Yaghi et al. synthesized a 3D-COF by dehydration condensation of tetrakis(4-aminophenyl)methane (1) and terephthalaldehyde.³⁾ The resultant COF was reported to have a diamond-like structure owing to the tetrahedral structure of 1.
　Furthermore, building blocks with tetrahedral centers such as tetrakis(4-ethynylphenyl)methane (2) and tetrakis(4-bromophenyl)methane (3) are useful for producing porous polymers. Synthesis of porous polymers by click reactions^4,5) and coupling reactions^4,6) using 2 or 3 have been already reported.