Synthesis of Three-Dimensional Covalent Organic Frameworks with Non-Interpenetrated Structures from an 8-Connected Node

Abstract

Three-dimensional covalent organic frameworks (3D COFs) have attracted significant research interest due to their unique structures. However, the interpenetration phenomenon exists in most 3D COFs, which compresses pore space, reduces effective pore volume and specific surface area, and thus limits the performance of these materials in fields such as adsorption and catalysis. Therefore, developing non-interpenetrated 3D COFs is challenging yet of great significance. In this study, a symmetry reduction strategy was employed to construct a jca topological 3D COF (JUC-643) with a unique double-helix structure. Powder X-ray diffraction (PXRD) and topological analysis confirmed it as a non-interpenetrated [4+3(+2)]-c net, overcoming the interpenetration tendency of traditional [8(+2)]-c or [6(+2)]-c net. Benefiting from the non-interpenetrated characteristic, the framework retains sufficient pore space, providing ample accommodation for molecular adsorption. At 298 K and 1 bar, JUC-643 exhibits adsorption capacities of 2.47 mmol·g^–1 for C₃H₈ and 3.32 mmol·g^–1 for n-C₄H₁₀. This study not only offers a generalizable method for the design of non-interpenetrated 3D COFs but also confirms their application potential in light hydrocarbon adsorption.

Keywords

Covalent organic frameworks / Symmetry reduction strategy / Non-interpenetrated net / Gas adsorption / Environmental chemistry / Networks / Conjugated polymers

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