Photomanipulation of the Mechanical Properties in a Liquid Crystal with Azo‐Containing Bent‐Core Mesogens

Abstract

We demonstrate the reversible photomanipulation of the bulk mechanical properties in the azobenzene-containing bent-core liquid crystal. The azobenzene groups in the mesogens exhibit reversible cis-trans photoisomerization abilities. An unprecedentedly large reduction by the factor of more than 5 of the splay elastic constant in a cybotactic-type nematic phase was found under exposure to the UV. This opens up the possibility to manipulate the mechanical properties of liquid crystals using light. The liquid crystal material is also distinguished by the sign inversion of low-frequency temperature-dependent dielectric anisotropy. Such behavior can be related to the presence of smectic-like nanoclusters both in the isotropic phase near the clearing point and in the cybotactic nematic phase.

Recent Progress in Liquid Crystal‐Based Smart Windows: Materials, Structures, and Design

“…[139] These smart windows are usually made of LC materials with light activity, in which the reorientation of LC molecules occurs under the exposure of light of certain wavelengths. [143,144] Photoinduced changes in molecular arrangement of LC materials cause the variation in optical states of the windows. [145][146][147] Most photochromism LC-based smart windows are only driven by the light with a certain wavelength and intensity, and the light is usually emitted by LEDs.…”

Multiple Azoarenes Based Systems – Photoswitching, Supramolecular Chemistry and Application Prospects

“…Over the years, a variety of multiple azoarene based liquid crystals have been prepared where azoarenes act both as mesogen and as the photoresponsive component [33–34] . The most recent reports (2020–2021) of multiazoarene based liquid crystals are A‐43 , [35] A‐44 [36] and A‐45 [37] . Supramolecular H‐bonded bent shaped liquid crystals containing two azoarene units such as A‐46 and A‐47 are also known (Figure 8).…”

“…[33][34] The most recent reports (2020-2021) of multiazoarene based liquid crystals are A-43, [35] A-44 [36] and A-45. [37] Supramolecular H-bonded bent shaped liquid crystals containing two azoarene units such as A-46 and A-47 are also known (Figure 8). Multi-azobenzene systems have also been used as photoresponsive chiral dopants, which can photo-transmit its chiral information to the host medium by arranging achiral nematic liquid crystal hosts in helical superstructures.…”