Tuning the stacking behaviour of a 2D covalent organic framework through non-covalent interactions

Haase, F.; Gottschling, K.; Stegbauer, L.; Germann, L. S.; Gutzler, R.; Duppel, V.; Vyas, V. S.; Kern, K.; Dinnebier, R. E. und Lotsch, B. V. (2017): Tuning the stacking behaviour of a 2D covalent organic framework through non-covalent interactions. In: Materials Chemistry Frontiers, Bd. 1, Nr. 7: S. 1354-1361

Abstract

Two-dimensional covalent organic frameworks (COFs) are crystalline porous materials composed of organic building blocks that are connected via covalent bonds within their layers, but through non-covalent interactions between the layers. The exact stacking sequence of the layers is of paramount importance for the optoelectronic, catalytic and sorption properties of these polymeric materials. The weak interlayer interactions lead to a variety of stacking geometries in COFs, which are both hard to characterize and poorly understood due to the low levels of crystallinity. Therefore, detailed insights into the stacking geometry in COFs is still largely elusive. In this work we show that the geometric and electronic features of the COF building blocks can be used to guide the stacking behavior of two related 2D imine COFs (TBI-COF and TTI-COF), which either adopt an averaged "eclipsed'' structure with apparent zero-offset stacking or a unidirectionally slip-stacked structure, respectively. These structural features are confirmed by XRPD and TEM measurements. Based on theoretical calculations, we were able to pinpoint the cause of the uniform slip-stacking geometry and high crystallinity of TTI-COF to the inherent self-complementarity of the building blocks and the resulting donor-acceptor-type stacking of the imine bonds in adjacent layers, which can serve as a more general design principle for the synthesis of highly crystalline COFs.

• Dokumententyp: Zeitschriftenartikel
• EU Funded Grant Agreement Number: 639233
• EU-Projekte: Horizon 2020 > ERC Grants > ERC Starting Grant > ERC Grant 639233: Fuel from sunlight: Covalent organic frameworks as integrated platforms for photocatalytic water splitting and CO2 reduction
• Fakultät: Chemie und Pharmazie > Department Chemie
• Themengebiete: 500 Naturwissenschaften und Mathematik > 540 Chemie
• Sprache: Englisch