Single-Crystal One-Dimensional Porous Ladder Covalent Polymers

The synthesis of single-crystal, one-dimensional (1D) polymers is of great importance but a formidable challenge. Herein, we report the synthesis of single-crystal 1D ladder polymers in solution by dynamic covalent chemistry. The three-dimensional electron diffraction technique was used to rigorously solve the structure of the crystalline polymers, unveiling that each polymer chain is connected by double covalent bridges and all polymer chains are packed in a staggered and interlaced manner by π-π stacking and hydrogen bonding interactions, making the crystalline polymers highly robust in both thermal and chemical stability. The synthesized single-crystal polymers possess permanent micropores and can efficiently remove CO₂ from the C₂H₂/CO₂ mixture to obtain high-purity C₂H₂, validated by dynamic breakthrough experiments. This work demonstrates the first example of constructing single-crystal 1D porous ladder polymers with double covalent bridges in solution for efficient C₂H₂/CO₂ separation.