OPTICALLY ACTIVE, A MESOGENIC REMAINING DIOXOLANYLACRYLIC AND DIOXOLANYL PROPIONIC ACID ESTERS, A METHOD FOR THE PRODUCTION THEREOF AND THEIR USE AS DOPING SUBSTANCES IN LIQUID CRYSTAL MIXTURES.

摘要

Optically active 1,3 dioxolane derivatives containing a mesogenic residue, of the general formula (I), are suitable as doping agents especially in ferro-electrical liquid crystal mixtures. The meanings of the symbols in the general formula are: R?1 is constructed similarly to the part of the general formula to the right of X or an alkyl or alkylene residue which may be substituted; R?2, R?3, R?4 = H or alkyl (R?4 may also be alkenyl) which may also be substituted [R?2, R?3 together with the C(2) of the dioxolane ring may be a cycloaliphate or a keto group]; j, l, n = zero, 1 or 2 and k, m = zero or 1 provided that if k = zero, n = zero also, if n = zero, m = zero also and l j + l + n 3; -A?1, -A?2, -A?3 = aromatic, heterocyclic or aliphatic ring system; -M?1,- M?2 = -CO-O, -O-CO, -CH2?CH2?, -CH=CH, -CH2?O, -OCH2?, -C=C and X = CH=CH, CH2?-CH2?. The special advantage of the compounds with the general formula (I) is that they can induce a high twisting capacity in a cholesteric phase without substantially affecting in the smectic C* phase the value of the spontaneous polarisation already in the mixture. They are therefore suitable for pitch compensation, especially for ferro-electrical liquid crystal mixtures.