Molecular Crystals and Liquid Crystals, Vol.449, 21-31, 2006
Photo-induced inversion of the cholesteric helix in systems containing 3(R)-methylcyclohexanone 6-arylidene derivatives
Induced cholesteric systems which were based on 4-pentyl-4'-cyanobiphenyl and contained 3(R)-methylcyclohexanone 6-arylidene derivatives as chiral dopants showed the helix inversion under UV light exposure due to the effective E-Z photo-isomerization of the dopant. Rather high twist extent produced during this process remained invariable under the subsequent irradiation or at elevated temperatures. The effect observed was driven by the sign and value difference in helical twisting powers of E- and Z-isomers of 3(R)-methylcyclohexanone derivatives. The cholesteric mixtures containing Z-isomers of 3(R)-methylcyclohexanone derivatives exhibited the selective visible light reflection.