Organic microporous crystals driven by pure C-H⋯π interactions with vapor-induced crystal-to-crystal transformations.

Organic porous crystals constructed by only a single kind of weak molecular interaction are invaluable to understanding the nature of the formation of organic porous materials and developing new types of porous materials. Here, we designed and synthesized two pure organic compounds of PBO and PBS through integrating planar dibenzothiophene/dibenzofuran and two phenothiazine groups together with twisted C-N bonds, which form organic microporous crystals with very good stability against strong acids and bases pure C-H⋯π interactions. Accordingly, the effective absorption of toluene has been successfully realized with an adsorbing capacity of 6.20 mmol g, regardless of the interference of water vapor. Excitingly, these microporous materials exhibit interesting crystal-to-crystal transformation (CCT) properties accompanied by changed pore size on being exposed to different organic vapors. Therefore, the desorption process of toluene could be completed through a simple exposure to dichloromethane (DCM) vapor and the second transformation of the crystal occurred in this process.