Crystallinity of Imide-Linked Two-Dimensional Polymers Depends on the Nucleophilicity of Triamine Building Blocks

Dynamic covalent chemistry, associated with reversible reactions, has allowed the synthesis of crystalline two-dimensional polymers (2DPs). However, strategies for the formation of imide-linked 2DPs (PI-2DPs) have not yet been extensively explored, because of the poor reversibility of amide linkages in amic acid intermediates. Here, we report how to control the reaction conditions for the formation of crystalline PI-2DPs. After studying five PI-2DPs cases, we found that the formation rate of amic acid intermediates before their imidization into imide rings plays a crucial role in the subsequent crystallinity of PI-2DPs. Furthermore, calculating the pKa values of the triamine monomers, which is closely related to their nucleophilicity (reactivity), also allows the crystallinity of the resulting PI-2DPs to be predicted. The findings may offer criteria for the design and synthesis of crystalline PI-2DPs.