| abstract |
Optically active dopants of the formula <IMAGE> I wherein A represents an optically active group selected from 1,1'-binaphthyl-2,2'-diyl, -CHR1-CHR2- or -CH(COOR3)-CH(COOR4)-; Z denotes a group -(CH2)4-, -O(CH2)3- or the trans form of -OCH2-CH=CH-; R1 is hydrogen, methyl, phenyl or cyclohexyl; R2 is methyl, phenyl or cyclohexyl; R3 and R4 denote alkyl; Y stands for -CO- or -CH2-; ring B represents 1,4-phenylene or trans-1,4-cyclohexylene; and R is hydrogen, alkyl, alkoxy or cyano, liquid crystalline mixtures which contain such dopants and their use for optical and electro-optical purposes. |