Self‐Waveguide Single‐Benzene Organic Crystal with Ultralow‐Temperature Elasticity as a Potential Flexible Material

Abstract

With the increasing popularity and burgeoning progress of space technology, the development of ultralowtemperature flexible functional materials is a great challenge. Herein, we report a highly emissive organic crystal combining ultralow-temperature elasticity and self-waveguide properties (when a crystal is excited, it emits light from itself, which travels through the crystal to the other end) based on a simple singlebenzene emitter. This crystal displayed excellent elastic bending ability in liquid nitrogen (LN). Preliminary experiments on optical waveguiding in the bent crystal demonstrated that the light generated by the crystal itself could be confined and propagated within the crystal body between 170 and À196 8C. These results not only suggest a guideline for designing functional organic crystals with ultralow-temperature elasticity but also expand the application region of flexible materials to extreme environments, such as space technology.

How Do Molecular Motions Affect Structures and Properties at Molecule and Aggregate Levels?

“…It is well known that organic crystalline materials are commonly rigid and brittle, and they usually crack, shatter or deform irreversibly under external stimuli. [28][29][30][31][32][33] Although the elastic organic crystals have been sporadically reported, [34][35][36][37][38][39][40][41] the MSP relationship of the elastic AIEgen crystals is another interesting issue without systematic research.…”

How Do Molecular Motions Affect Structures and Properties at Molecule and Aggregate Levels?

“…It is well known that organic crystalline materials are commonly rigid and brittle, and they usually crack, shatter or deform irreversibly under external stimuli. [28][29][30][31][32][33] Although the elastic organic crystals have been sporadically reported, [34][35][36][37][38][39][40][41] the MSP relationship of the elastic AIEgen crystals is another interesting issue without systematic research. On the contrary, PhCz and PyCz broke easily in the presence of external force even though PyCz had a similar molecular conformation as ClPyCz (Figure S17).…”

Adaptable Optical Microwaveguides From Mechanically Flexible Crystalline Materials

“…Because these are treated as restorative interactions to impart elasticity the selection of soft groups may influence the outcome of mechanical properties [1,12,25] . Further, Emission color depends upon several factors such as vibronic coupling, effects of electron withdrawing substituents in the periphery, unsymmetrical aromatic rings across connecting linkage, excited‐state intramolecular proton transfer and formation of intermolecular aggregates in solid states [26,27,28] …”

“…Here, we report on a green‐emitting halogenated Schiff base crystal ( 1 ) [4] and red‐emitting halogen‐substituted azine crystal ( 2 ) [28] (Figures 1a and 1d). Both the crystals were grown as long acicular crystals.…”