Single-Crystal-to-Single-Crystal Synthesis of an Adaptive Two-Dimensional Polymer with Dynamic Pores

The synthesis of defect-free, large-area two-dimensional (2D) polymers with dynamic functionality remains a formidable challenge. Here, we report a transformative approach to 2D polymer synthesis via heat-induced topochemical azide-alkyne cycloaddition (TAAC), enabling the single-crystal-to-single-crystal (SCSC) formation of a novel 2D polymer. Unlike conventional rigid 2D frameworks, our design incorporates flexible linkers, imbuing the resulting polymer with dynamic and adaptive pores. We demonstrate reversible guest uptake and exchange, providing unprecedented atomic-resolution insights into host-guest interactions and framework conformational changes. Furthermore, the successful exfoliation of these crystalline 2D polymers into robust, free-standing sheets highlights their practical utility. This work establishes a powerful platform for designing next-generation adaptive materials with precisely controlled molecular recognition and transport capabilities.