Flexible and Densely Packed π-Figuration System: Creating Elastic Organic Crystals of π-Conjugated Molecules

pi-Conjugated molecules have attracted much attention over recent years and have applications in various organic devices. The crystals of these molecules are attractive materials for developing unique and/or high-performance devices due to anisotropic densely packed supramolecular 3D self-assembled structures. However, these are not flexible and therefore not suitable for flexible/wearable devices. In this article, the author's recent work on elastic crystals based on supramolecular synthon of targeted crystal structure (fibril lamella of slip-stacked molecular wires from rigid and planar pi-conjugated molecules) and their unique applications are summarized. Unlike common organic crystals, designed thiophene-fluoroarene pi-conjugated molecules exhibits elastic bending flexibility with pi-functionality. This supramolecular design concept offers top-down synthesis of crystalline fibers and films. Moreover, the functionality and flexibility of such a crystal realized both high-performance flexible fluorescent waveguide and reversible mechnofluo-rochromic behaviors.