Related Experiment Video
Updated: Jul 10, 2025

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals
Published on: May 29, 2018
Photoactuators Based on Plastically Flexible α-Cyanostilbene Molecular Crystals Driven by the Solid-State [2+2]
Yiwei Wei1, Kui Chen1, Shanshan Zhu1
1National Engineering Research Center of Industrial Crystallization Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, P. R. China.
Abstract:
Organic photomechanical molecular crystals are promising candidates for photoactuators, which have potential applications as smart materials in various fields. However, it is still challenging to fabricate photomechanical molecular crystals with flexibility because most of the molecular crystals are brittle and the mechanism of flexible crystals remains controversial. Here, a plastically flexible α-cyanostilbene crystal has been synthesized that can undergo solid-state [2+2] cycloaddition reaction under violet or UV irradiation and exhibits excellent photomechanical bending properties. A hook-shaped crystal can lift 0.7 mg object upward by 1.5 cm, which proves its potential for application as photoactuators. When complex with the agarose polymer, the molecules will be in the form of macroscopic crystals, which can drive the composite films to exhibit excellent photomechanical bending performance. Upon irradiation with UV light, the composite film can quickly lift 18.0 mg object upward by 0.3 cm. The results of this work may facilitate the application of macroscale crystals as photoactuators.
Related Concept Videos
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Cycloaddition Reactions: Overview
Cycloaddition Reactions: MO Requirements for Thermal Activation
Thermal and Photochemical Electrocyclic Reactions: Overview
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.

