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Chiral, Thermally Irreversible and Quasi‐Stealth Photochromic Dopant to Control Selective Reflection Wavelength of Cholesteric Liquid Crystal
Author(s) -
Kurosaki Yoshihisa,
Sagisaka Toshiya,
Matsushima Tomoo,
Ubukata Takashi,
Yokoyama Yasushi
Publication year - 2020
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.202000309
Subject(s) - photochromism , dopant , cholesteric liquid crystal , photochemistry , visible spectrum , liquid crystal , materials science , moiety , wavelength , molecule , reflection (computer programming) , absorption (acoustics) , polymer , optoelectronics , chemistry , doping , organic chemistry , computer science , composite material , programming language
A chiral and thermally irreversible photochromic fulgide derivative incorporating an (R)‐ binaphthol unit in its acid anhydride moiety was used for the photoswitching of the pitch length of cholesteric liquid crystals. Since the absorption maximum wavelengths of both thermally stable photoisomers are nearly in the UV region (quasi‐stealth photochromism), it can be exposed to visible light without inducing photochromic reactions. Therefore, when the photoswitching molecule is added to a permanent cholesteric liquid crystal whose reflection light wavelength is in the visible region, the UV light‐induced photochromic reaction of the photoswitching molecule changes the wavelength of the reflection light in the visible light region. We have succeeded in regulating the color of cholesteric liquid crystalline cells between red and blue upon UV light irradiation. Attempts to introduce this system in polymer dispersed cholesteric liquid crystals are also described.