Diverse tetracyanodihydrodipyrazinopyrazine clathrate crystals assembled from weak intermolecular interactions

Tetracyanodihydrodipyrazinopyrazines with two mesityl (2,4,6-trimethylphenyl) groups formed clathrate crystals with 15 kinds of organic solvents. Two common types of host molecular networks were observed in the crystals. Theoretical calculations indicated that these host networks are constructed from π–π and CN–π interactions. As these intermolecular interactions are relatively weak, the host network can change flexibly in response to guest molecules. Guest-free crystals can be reversibly transformed into clathrate crystals through crystal-to-crystal phase transitions via the adsorption/desorption of solvent vapor.