Three-Dimensional Anionic Cyclodextrin-Based Covalent Organic Frameworks

Three-dimensional covalent organic frameworks (3D COFs) are promising crystalline materials with well-defined structures, high porosity, and low density; however, the limited choice of building blocks and synthetic difficulties have hampered their development. Herein, we used a flexible and aliphatic macrocycle, namely γ-cyclodextrin (γ-CD), as the soft struts for the construction of a polymeric and periodic 3D extended network, with the units joined via tetrakis(spiroborate) tetrahedra with various counterions. The inclusion of pliable moieties in the robust open framework endows these CD-COFs with dynamic features, leading to a prominent Li ion conductivity of up to 2.7 mS cm⁻¹ at 30 °C and excellent long-term Li ion stripping/plating stability. Exchanging the counterions within the pores can effectively modulate the interactions between the CD-COF and CO₂ molecules.