ABSTRACT
Imine-linked covalent organic frameworks (imine-COFs) represent the most sought-after class of COFs due to their broad monomer scope and ease of synthesis. Owing to the reversible nature of imine linkages, however, the chemical stability of most imine-COFs is still far from adequate. In this context, emerging strategies, ranging from linkage chemistry to interlayer interaction, have been employed to construct stable imine-COFs for their applications in electronics, sensing, and energy storage devices. This Concept article summarizes the latest advances aimed at tuning the structural stability of imine-COFs. Furthermore, this Concept provides a prospective for the precise design of stable imine-COFs based on the characteristics of structure, physical properties, and chemical functions, as well as the mechanism of structure locking and stabilization during crystal growth.
ABSTRACT
The development of effective, stable anhydrous proton-conductive materials is vital but challenging. Covalent organic frameworks (COFs) are promising platforms for ion and molecule conduction owing to their pre-designable structures and tailor-made functionalities. However, their poor chemical stability is due to weak interlayer interactions and intrinsic reversibility of linkages. Herein, we present a strategy for enhancing the interlayer interactions of two-dimensional COFs via importing planar, rigid triazine units into the center of C3 -symmetric monomers. The developed triazine-core-based COF (denoted as TPT-COF) possesses a well-defined crystalline structure, ordered nanochannels, and prominent porosity. The proton conductivity was ≈10 times those of non-triazinyl COFs, even reaching up to 1.27×10-2 â S cm-1 at 160 °C. Furthermore, the TPT-COF exhibited structural ultrastability, making it an effective proton transport platform with remarkable conductivity and long-term durability.
