Noncovalent π-stacked organic frameworks (πOFs): A promising class of porous materials

Noncovalent π-stacked organic frameworks (πOFs) are a subclass of porous materials that consist of crystalline networks formed by self-assembly of organic building blocks through π-π interactions. Weak intermolecular interactions including π-π interactions have been well studied in the field of supramolecular chemistry and further employed for constructing porous molecular materials. The flexible, reversible, and conductive nature of π-π interactions and π-delocalized supramolecular frameworks impart advantageous attributes to πOFs, including solution processability, self-healing capability, notable carrier mobility and excellent stability. These features make πOFs ideal candidates not only for conventional applications like gas separation, molecular structure determination, and electrocatalysis, but also for endeavors that traditional porous materials can hardly pursue. In this review, we describe the evolution of πOFs chronologically, starting from the development of the π-π interactions model, which has led to the creation of complicated supramolecular architectures and the introduction of the concept of πOFs. Through comparing πOFs with other prevailing porous materials, we highlight their unique aspects of fundamental chemistry and practical advantages. We also summarize the physical properties and applications of πOFs through elucidating the structure–function correlations. Finally, we discuss the design strategies of πOFs that allow for emerging functional applications beyond what traditional porous materials have achieved.