Reticular chemistry guided construction of Olympic rings-inspired two-dimensional covalent organic frameworks for photocatalysis

Abstract

Two-dimensional covalent organic frameworks (2D-COFs) have received extensive attention from structural design to application explorations. Top-down design and discovery of new structures of 2D-COFs still remains a great challenge. In this work, under the guidance of reticular chemistry, we rationally designed and synthesized four highly crystalline 2D-COFs (HIAM-0028 to HIAM-0031) inspired by the Olympic rings using hexatopic aldehydes and diamine-based building units through a C₆ + C₂ approach. Due to their capacity to generate reactive oxygen species and suitable electronic structures, these COFs can be used as heterogeneous photocatalysts for the cycloaddition reaction of tertiary anilines and maleimides. HIAM-0030 exhibits the best photocatalytic performance and can be used to synthesize the target compound on a gram scale with a yield of >93%, which is attributed to its lower exciton binding energy, efficient separation and migration of photogenerated charges. This work represents a great example of building COFs with unique structures guided by reticular chemistry and provides a class of efficient photocatalysts for organic transformation.