Helical mesoscopic crystals based on an achiral charge-transfer complex with controllable untwisting/breaking

The development of synthetic helical structures from achiral molecules and stimulus-responsive shape transformations are vital for biomimetics and mechanical actuators. A stimulus regarded as the force to induce chirality modulation plays a significant role in the helical supramolecular structure design through symmetry breaking. Herein, we synthesized a metastable complex Form 1 crystal composed of pyrene and (4,8-bis(dicyanomethylene)-4,8-dihydrobenzo[1,2-b:4,5-b′]-dithiophen-e) DTTCNQ components with a torsional backbone by C-H⋯N hydrogen bondsviaa quick cooling method. The helix motion kinetics of Form 1 depends on the intrinsic factor (crystal thickness) and external stimuli (polar solvents). The self-assembled helical microstructures grow into needle-like crystals in liquid mediaviaan untwistingprocess. Furthermore, they undergo predictable deformation of untwisting or breaking under a stimulus-responsive strain-relaxing phase transformation. This work illustrates a new approach in the mediated formation of helical morphologies from achiral binary supramolecules and dynamic motion, which is vital for biomimetics and mechanical actuators.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Solution-processed self-assemble engineering PDI derivative polymorphisms with optoelectrical property tuning in organic field-effect transistors

The crystal polymorphism study leads to an explosion of science research, related to many fields, such as organic semiconductors, pharmaceuticals, pigments, food, and explosives. Two different crystal phases of a perylene diimide derivative (4FPEPTC) have been prepared via a simple and efficient solution method. Via changing the concentration of the solution, we observed the polymorphisms clearly, wire-shape (α phase) and ribbon-like (β phase) crystals differed in the stacking mode and short-contacts. Moreover, the as-prepared n-channel microcrystal-based devices demonstrated distinct electron mobilities that of α phase architecture higher than β phase structure and obvious photoresponse discrepancy. Theoretical calculations further confirmed this phenomena, which help us to understand the structure-property relationship in this crystal polymorph. Our study indicates that the investigation of polymorphisms could be considered as a very useful method to realize functional property modulation and benefits the development of organic (opto)electronics.SCOPUS: ar.jinfo:eu-repo/semantics/publishe