Claims
1 A compound of Formula

Formula
wherein

n may be 0-5,
m may be 1-5,
p may be 1-9,
q may be 0, 1 or 2,
A_{1 t} A₂ are independently chosen from 1 ,4-dιsubstιtuted benzene, 2,5-dιsubstιtuted pynmidine, or 2,5-dιsubstιtuted pyridme, trans- 1 ,4-dιsubstιtuted cyclohexane, trans- 2,5-disubstituted dioxane, the aromatic rings may be laterally substituted with F, Cl, Br or CN, Z may be O, COO, OOC,
Z₂, Z₃ are independently chosen from a direct bond, COO, OOC, C2H4, CH2O, OCH2 -c≡c —

provided that when Z₁ is O and m is 1 , 3 or 5 the carbon-carbon double bond configuration is E and when n is 2 or 4 the carbon-carbon double bond configuration is Z and when Z is COO or OOC and m is 0, 2 or 4 the carbon-carbon double bond configuration is E and when n is 1 , 3 or 5 the carbon-carbon double bond configuration is Z

2 A compound according to claim 1 wherein


p is 3-7,

Ai is 1 ,4-dιsubstιtuted benzene, A₂ is trans- 1 ,4-dιsubstιtuted cyclohexane,
Zi is O or COO, Z₂ and Z₃ are direct bonds

3 A compound according to claim 2 wherein n + m is ≤ 7

4 A liquid crystal mixture comprising at least one of the compounds according to claim 1

5 A liquid crystal mixture according to claim 4 wherein the mixture is a nematic liquid crystal mixture

6 A liquid crystal mixture according to claim 4 wherein the mixture is a cholesteric liquid crystal mixture.

7 A device comprising two spaced cell walls each bearing electrode structures and treated on at least one facing surface with an alignment layer, a layer of a liquid crystal material enclosed between the cell walls, characterised in that it incorporates the liquid crystal mixture as claimed in any of claims 4, 5, 6

8 A device according to claim 7 wherein the device is a twisted nematic device

9 A device according to claim 7 wherein the device is a super-twisted nematic device