Anisotropic compounds having nematic phase and liquid crystal mixtures

Abstract

Anisotropic compounds having a nematic phase have the formula ##STR1## wherein A is a cyclic radical selected from the group consisting of ##STR2## Z is selected from the group consisting of a single bond, a --CH2CH2-- group, a methyleneoxy group and an oxymethylene group, n is 1 or 2, p is 0, 1, or 2, r is 0 or 1, X is selected from the group consisting of fluorine, chlorine, bromine, iodine, nitrile and methyl, R.sup.1 and R.sup.2 are selected from the group consisting of hydrogen, C.sub.1 -C.sub.12 -alkyl, C.sub.1 -C.sub.12 -alkoxy, C.sub.1 -C.sub.12 -alkanoyloxy and C.sub.1 -C.sub.12 -alkylamino and cyclic groups of the formulas ##STR3## wherein R.sup.3 through R.sup.6 are selected from the group consisting of hydrogen, C.sub.1 -C.sub.12 -alkyl, C.sub.1 -C.sub.12 -alkoxy, C.sub.1 -C.sub.12 -alkanoyloxy, and C.sub.1 -C.sub.12 -alkylamino, and Z.sup.2 through Z.sup.6 represent a Z group, with the provisos that: (A) none of the above aromatic radicals (10), (11), (13), (14) or (15) is directly bonded to the C-atom of a methyleneoxy or oxymethylene group; and (B) at least one X group is methyl when only one or none of the groups R.sup.1 and R.sup.2 is a cyclic radical of formulas (13) or (16), A has the formula (12), Z is a single bond, and any of Z.sup.3 or Z.sup.6, if present, is a single bond. Compounds having the defined lateral substituents on the rings have a reduced tendency to form smectic phases as compared with the compounds not having such lateral substituents.

Dependencies are inferred from the claim text.