Convalent Organic Frameworks

© Prof. Dr. Arne Thomas

Covalent organic frameworks are covalently connected, purely organic structures with extended, periodic architectures in two or three dimensions. In general, for the formation of COFs it is necessary that the condensation reaction occur in a reversible or dynamic fashion, that is, chemical bonds of the forming polymer network have to close and open, yielding in consequence the thermodynamically (meta)stable, yet crystalline structure. To create covalently bound organic frameworks, either covalent bonding schemes have to be identified which are rather weak and thus can reopen under mild conditions, or harsher reaction conditions have to be applied which however have to selectively and reversibly open and close on certain bond in the network. COFs have been synthesized in our group by trimerization of dicyano-compounds. To enable reversibility, the reaction had to be carried out under much harsher reaction conditions. Trimerization of 1,4-dicyanobenzene in molten zinc chloride at 400°C yield covalent triazine-based frameworks (CTF) with high chemical and thermal robustness. The synthesis in salt melts also allow to prepare networks at even higher temperatures yielding materials with hierarchical pore structures and high surface areas of up to 3000 m2/g. The formation of the triazine rings inherently yield a high amount of heteroatoms in the networks which can be used for example for the coordination and thus stabilization of metal nanoparticles creating active and stable catalysts.

Relevant Publications

“Covalent Triazine Framework as Catalytic Support for Liquid Phase Reaction” C. E. Chan-Thaw, A. Villa, P. Katekomol, D. S. Su, A. Thomas, L. Prati, Nano Lett.2010, 10, 537
“Solid Catalysts for the Selective Low-Temperature Oxidation of Methane to Methanol” R. Palkovits, M. Antonietti, P. Kuhn, A. Thomas, F. Schuth, Angew. Chem.Int. Ed. 2009, 48, 6909
“Toward Tailorable Porous Organic Polymer Networks: A High-Temperature Dynamic Polymerization Scheme Based on Aromatic Nitriles” P. Kuhn, A. Thomas, M. Antonietti, Macromolecules 2009, 42, 319-326
“Template-Free Tuning of Nanopores in Carbonaceous Polymers through Ionothermal Synthesis”
P. Kuhn, A. Forget, J. Hartmann, A. Thomas, M. Antonietti, Adv. Mater. 2009, 21, 897-901
“Everything is surface: tunable polymer organic frameworks with ultrahigh dye sorption capacity”
P. Kuhn, K. Krüger, A. Thomas, M. Antonietti, Chem. Commun. 2008, 5815-5817
“From Microporous Regular Frameworks to Mesoporous Materials with Ultrahigh Surface Area: Dynamic Reorganization of Porous Polymer Networks “ P. Kuhn, A. Forget, D. Su, A. Thomas, M. Antonietti, J. Amer. Chem. 2008, 130, 13333-13337
“Porous, Covalent Triazine-Based Organic Frameworks Prepared by Ionothermal Synthesis” P. Kuhn, M. Antonietti, A. Thomas, Angew. Chem. Int. Ed. 2008, 47, 3450-3453