Multiple-component covalent organic frameworks

Abstract

Covalent organic frameworks are a class of crystalline porous polymers that integrate molecular building blocks into periodic structures and are usually synthesized using two-component [1+1] condensation systems comprised of one knot and one linker. Here we report a general strategy based on multiple-component [1+2] and [1+3] condensation systems that enable the use of one knot and two or three linker units for the synthesis of hexagonal and tetragonal multiple-component covalent organic frameworks. Unlike two-component systems, multiple-component covalent organic frameworks feature asymmetric tiling of organic units into anisotropic skeletons and unusually shaped pores. This strategy not only expands the structural complexity of skeletons and pores but also greatly enhances their structural diversity. This synthetic platform is also widely applicable to multiple-component electron donor–acceptor systems, which lead to electronic properties that are not simply linear summations of those of the conventional [1+1] counterparts.

Photoactive and Conducting Covalent Organic Frameworks

“…This library was accessed through a mixed monomer synthesis approach where subunits of a similar symmetry but different dimensions resulted in pores of different aspect ratios. [12] …”

Kovalente organische Netzwerke und Käfigverbindungen: Design und Anwendungen von polymeren und diskreten organischen Gerüsten

“…Die Einführung von sterisch anspruchsvollen Substitutenten kann jedoch zu einem Vermeiden von kleineren Poren und damit zu einem Wechsel der COF-Topologie führen. [172] Narzisstische Selbstsortierung wurde bereits füre inige organische Käfige beobachtet. Auch soziale Selbstsortierung von Mehr-Komponenten-Mischungen führte zu 2D-COFs mit einem dreifachen Porensystem [167] oder anisotropen Strukturen mit ungewçhnlichen Poren von niedriger Symmetrie.…”

Engineered 2D Polymers: Current Status and Future Trend

“…These crystalline porous polymeric materials are emerging as atomically precise integration of organic units extended into 2D structures with periodic skeletons and ordered programmable nanopores decided by the geometry and dimensions of the building blocks involved in the topological evolution of structural periodicity. The diversity possible in the building blocks and covalent linkage topology schemes make these COFs as unique platforms having structurally controlled functional designs offering confined molecular spaces for the interplay of photons, excitons, electrons, holes, ions and guest molecules, and thereby exhibiting unique physico-chemical properties as discussed in a recent review [8,9].…”

“…Unlike conventional [1+1] COFs, MC-COFs demonstrated enhanced complexity in both skeletons and pores by creating sequenced anisotropic tiling and unusually shaped ordered pores. Further, it was shown possible to employ multiple-component electron donor-acceptor COFs triggering strong electronic correlations among the latticed π-components exhibiting enhanced electronic properties [8][9]. Alternately, it is also possible to consider 2DPs as a lamellar form of covalent organic frameworks (COFs) designed and synthesized from extended crystalline organic porous structures made from light elements (H, B, C, N, and O) known to form strong covalent bonds in materials like diamond, graphite, and boron nitride.…”

“…The 2D COFs form 2DP sheets comprising of periodic columnar π-arrays and orientated one-dimensional (1D) channels. By virtue of their ordered π-structure and high porosity, COFs have emerged as a powerful platform for designing functional materials and have shown outstanding performance in various fields, including gas adsorption, light emitters, catalysis, semiconductors, proton conductions and energy conversion and storage [8,9].COFs are typically synthesized via topologically directed [1+1] condensation reactions between a knot and a linker unit together. For example, a maximum of 10 different COFs are possible to synthesize from a library of one knot and 10 linkers.…”