Abstract: Cholesteric liquid crystals have been widely applied in displays, smart optics, sensing and other fields due to their unique helical structures. In this work, two chiral photoswitches (BC2 and BC4) are designed and synthesized by introducing 2 and 4 alkyl chains into the side aryl groups based on intrinsic chiral diarylethene, which possesses excellent bistability and enantiospecific photoisomerization. Then we dope these chiral photoswitches into commercial liquid crystals to construct photoresponsive cholesteric liquid crystal systems, and investigate the photo-manipulation performance induced by different alkyl chains number. The results clearly show that BC4 exhibits excellent photo-manipulation performance on liquid crystal, showing the large helical twisting power of 260.59 μm-1 and the variation of 227.11 μm-1, with wide range of reflection spectra to 1100 nm, which are all better than BC2 (219.16 μm-1, 174.06 μm-1, 900 nm). This study provides an effective strategy for the regulation of cholesteric liquid crystal properties and a promising technical solution for the optical anti-counterfeiting field.

Key words: Photochromism, Diarylethylene, Intrinsic chirality, van der Waals force, Cholesteric liquid crystal