High birefringence liquid crystal compounds

Abstract

High birefringence liquid crystal dopants having the formula: R.sub.1 X--C--.tbd.--D--T wherein C and D, independently of one another, are aromatic ring systems each of which has one or two 5-member or 6-member carbon rings wherein one or two carbons of any ring in C or D can be substituted with a nitrogen, oxygen or sulfur atom and wherein any ring in C or D can be substituted with one or two halogen atoms; T is a halogen, haloalkyl, haloalkoxy, vinylhalide or a group YR.sub.2 where Y is a single bond, double bond, triple bond, --COS--, --CS.sub.2 --, --CH.dbd.CH--CO--S--, --CH.dbd.CH--CS--S-- or --CH.dbd.CH--CO--O-- group; X is a single bond, double bond, triple bond, O or S atoms or a cyclohexane or cyclohexene group, Z--Q--W, where Q is a cyclohexane or cyclohexene ring in which one or two of the ring carbons can be replaced with an O atom or in which one or more of the ring carbons can be substituted with a halogen atom or a cyano group, Z is a single bond or an O or S atom and W is a single bond, a --CH.sub.2 -- group, a --CH2--CH.sub.2 -- group, or a --CH.sub.2 --O-- group; and R.sub.l and R.sub.2 are, independently of one another, alkyl groups having from about 3 to about 20 carbon atoms in which one or more --CH.sub.2 -- groups can be halogenated, two neighboring --CH.sub.2 -- groups can be substituted with an epoxide, or one or more non-neighboring --CH.sub.2 -- groups can be substituted with a double bond, triple bond, an O atom, a S atom, or a silyl group SiR.sub.A R.sub.B wherein R.sub.A and R.sub.B, independently of one another, can be alkyl or alkenyl groups having 1 to about 6 carbon atoms are provided. More specifically, high birefringence dopants that are alkynyl tolanes dialkynyl tolanes and tolanes having cinnamate ester tails and derivatives of those tails are provided. High birefringence dopants also possess UV stability, IR clarity and other properties that affect LC properties.

Dependencies are inferred from the claim text.