1,6-Anthrazoline-linked π-Conjugated Macrocycles and Two-dimensional Polymer via Friedländer Synthesis

Synthesis of π-conjugated crystalline two-dimensional (2D) polymers remains largely unexplored due to limited synthetic methodology. Herein, we report the preparation of a 1,6-anthrazoline (AZ)-linked crystalline 2D polymer AZP via acid mediated Friedlander synthesis. The feasibility was examined first by two model reactions, followed by synthesis of three AZ-based macrocycles MCn (n=5-7), in which hexagonal MC6 was isolated as the major product. The favorable macrocycle formation could be largely attributed to the dynamic feature of Friedlander synthesis, which involves both imine condensation and aldol condensation. The structure and crystallinity of AZP were confirmed by experiments and simulation. The skeletons of the macrocycles and polymer consist of all-sp2 hybridized C/N atoms and are thus π-conjugated and electro-active. Our studies provide a rational way to access kinetically stable 2D crystalline polymers by combination of different dynamic covalent chemistries.