Chiral π-Conjugated Liquid Crystals: Impacts of Ethynyl Linker and Bilateral Symmetry on the Molecular Packing and Functions

Abstract

Recently, various chiral aromatic compounds, including chiral π-conjugated liquid crystals, have been developed for their unique photofunctions. One of the typical photofunctions is the bulk photovoltaic effect of ferroelectric π-conjugated liquid crystals, which integrates a polar environment based on molecular chirality with an extended π-conjugation system. Tuning the spectral properties and molecular packing is essential for improving the optical functions of the chiral π-conjugated liquid crystals. Herein, we examined the effects of an ethynyl linker and bilateral symmetry on the liquid-crystalline (LC) properties and π-conjugated system through detailed characterization via polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction analysis. The spreading of the π-conjugated system was evaluated using UV–vis absorption and photoluminescence spectroscopy. Bilateral symmetry affects the LC and photoluminescent properties. Hetero-substitution with a sparse ethynyl linker likely allows the formation of an interdigitated smectic LC structure. Because the molecular packing and photophysical properties can affect the photo- and electrical functions, we believe this study can promote the molecular design of novel functional π-conjugated materials, such as chiral ferroelectric π-conjugated liquid crystals, exhibiting the bulk photovoltaic effect.

Nano-structuration influence on the polyimide-based spatial light modulator’s parameters

“…Moreover, the specific organic molecular crystal and classical ones were presented [16,18,26] to use them in the modulation technique area. Furthermore, novel interesting architecture of the LC structures and features of the schemes are considered [20,[31][32][33][34][35] . It should be remembered that basically three famous schemes can be used in order to operate with the SLM structure and to predict the unique properties.…”

“…The effective operation of the LC-SLM is connected with some geometric (constructions, scheme to activate the devices by the external fields) and with the physical-chemical parameters, which regarded not only to the specific native parameters of the modulators, but also depended on the modifications, for example, via nano-structuring of the interface, photo layer or modulating compound [9,13,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46] . So, it should be clarified why the study of the parameters of the classical or modified SLMs is so important?…”