Metalorganic Frameworks and Electroactive Networks

Crystalline porous networks resulting from molecular building blocks (covalent organic frameworks) and surfactant-templated polymer networks that can be graphitized are of interest for their potential electronic and optoelectronic properties. For example, we have recently created the largest crystalline open pore system with 4 nm pore diameter based on condensed aromatic building blocks. This project is presently extended to the condensation of redox-active building blocks into novel mesoporous structures.
We pursue the synthesis of microporous zeolites and micro- and mesoporous metalorganic frameworks with attractive porosity features using microscale high-throughput technologies. Some of these structures have unusual selective ion-exchange properties, others are of interest for their hierarchical porosity. We have discovered that some of these materials can be grown as oriented thin crystal films at the interface of self-assembled molecular monolayers. This morphology is attractive for the design of molecularly selective chemical sensors, for example based upon mass changes on a piezoelectric device or optical changes in a multilayer stack.

Key publications:

  • A Covalent Organic Framework with 4 nm Open Pores: M. Dogru, A. Sonnauer, A. Gavryushin, P. Knochel, T. Bein, Chem. Comm. 2011, 47, 1707-1709.
    Giant pores: A Covalent Organic Framework obtained from the co-condensation of a tetrahydroxyanthracene and a trigonal boronic acid forms a crystalline hexagonal channel structure with mesopores of 4.0 nm diameter.

  • Oriented Nanoscale Films of Metal–Organic Frameworks By Room-Temperature Gel-Layer Synthesis: A. Schödel, C. Scherb, T. Bein, Angew. Chem. Int. Ed. 2010, 49, 7225-7228.
    A gel-layer-based strategy is used for the growth of highly oriented thin films of metal–organic frameworks on self-assembled monolayers attached to a gold slide. The monolayer is loaded with the metal-salt-containing poly(ethylene glycol) gel layer (see picture; metal ions in red) and covered with a solution containing the linker molecules (blue).

  • Two-Dimensional-Hexagonal Periodic Mesoporous Polymer Resin Thin Films by Soft Templating: J. Schuster, R. Köhn, A. Keilbach, M. Döblinger, H. Amenitsch, T. Bein, Chem. Mater. 2009, 21, 5754-5762.
    Two-dimensional (2D)-hexagonal (plane group, p6mm) mesoporous polymer resin thin films were obtained through evaporation-induced organic-organic self-assembly of a preformed oligomeric resol precursor and the triblock copolymer template pluronic P123. The films are crack-free with tunable homogeneous thicknesses and show either a 2D-hexagonal or lamellar mesostructure. An additional, yet unknown, three-dimensional (3D) mesostructure was also found. The mesoporous polymer resin films can serve as precursors for various mesoporous carbon structures.

  • Directing the Structure of Metal–Organic Frameworks by Oriented Surface Growth on an Organic Monolayer: C. Scherb, A. Schödel, T. Bein, Angew. Chem. Int. Ed. 2008, 47, 5777-5779.
    Orientation and structure of porous metal–organic frameworks (MOFs) based on iron and 1,4-benzenedicarboxylic acid can be controlled by heterogeneous nucleation on self-assembled monolayers of mercaptohexadecanoic acid (MHDA). Thus, the product of homogeneous nucleation is the MOF Fe-MIL-53, whereas in the same crystallization solution, oriented Fe-MIL-88B grows on a MHDA-functionalized gold surface.