Single-Crystal Three-Dimensional Covalent Organic Framework Constructed from 6-Connected Triangular Prism Node.

Abstract

The limited structural diversity of three-dimensional covalent organic frameworks (3D COFs) greatly restricts their application exploration. Therefore, there is an urgent need to expand their library of molecular building blocks, such as the development of highly connected (>4 reaction sites) polyhedral nodes. Herein, by precisely controlling the precursor conformation, we rationally designed a new 6-connected triangular prism node derived from the triphenylbenzene molecule and further used it to construct a novel 3D COF (3D-TMTAPB-COF) via imine condensation reaction. Surprisingly, without the addition of competing reagents, 3D-TMTAPB-COF crystallized directly into single crystals of ∼15 μm in size and was determined to adopt a rare 6-fold interpenetrated (Class IIIa interpenetration) acs topology. In addition, 3D-TMTAPB-COF showed a high SF6 adsorption capacity (60.9 cm3 g-1) and good SF6/N2 selectivity (335) at 298 K and 1 bar, superior to those of most crystalline porous materials. This work not only confirms the possibility of growing large-size single-crystal 3D COFs formed with strong covalent bonds by a solvothermal method in the absence of modulators, but also reports a novel triangular prism node for future construction of 3D COFs with interesting applications.