Substitution of 1,3,6,8-tetraethynylpyrene with sterically bulky trimethylsilyl groups enabled four modes of molecular packing, two polymorphs (triclinic system (Y-form) and "loose" crystal Colho (OK-form)), a "rigid" liquid crystalline phase Colho (OC-form), and an amorphous phase (OA-form), which emitted fluorescence at different wavelengths under UV light. The four phases could be interconverted by physical stimuli such as heating, grinding by mortar and pestle, and exposing to the vapor of organic solvents.
Bibliographical noteFunding Information:
This work was supported by JSPS KAKENHI Grant Numbers JP16H01164 in Middle Molecular Strategy and JP15K05440, the Okayama Prefecture Industrial Promotion Foundation and Grant for Promotion of OUS Research Projects. AO is grateful to Professor Motohiro Akazome, Chiba University and Professor Hajime Maeda, Kanazawa University for the kind measurement of XRD and the helpful discussion, respectively.