Acetylenes

A liquid crystalline mixture comprising at least two components, wherein at least one of those components is a compound of the formula:

• ##STR26## wherein A together with ring B comprise a central group of the formula:
• ##STR27## wherein ring A.sup.12 is trans-1,4-disubstituted cyclohexane, trans-2,5-disubstituted 1,3-dioxane linked in the 2-position with ring B, or when ring B is trans-1,4-disubstituted cyclohexane or R.sup.2 is straight-chain alkyl of 1 to 7 carbon atoms, ring A.sup.12 l also can be 1,4-phenylene or 2,5-disubstituted pyrimidine linked in the 2-position with ring B;
• ##STR28## wherein ring A.sup.1 is 1,4-phenylene, or trans-1,4-disubstituted cyclohexane;
• or ##STR29## wherein ring A.sup.2 is 1,4-phenylene or trans-1,4-disubstituted cyclohexane and E is --COO-- or --OOC--;
• ring B is 1,4-phenylene or trans-1,4-disubstituted cyclohexane;
• R.sup.1 is straight-chain alkyl of 1 to 9 carbon atoms or when R.sup.1 is attached to a benzene or a pyrimidine ring, R.sup.1 also is straight-chain alkoxy of 1 to 9 carbon atoms;
• and R.sup.2 is cyano or straight-chain alkyl of 1 to 7 carbon atoms.

An electro-optical cell comprising:

• (a) two-plate means;
• (b) a liquid crystal disposed between the plate means and including a dielectric of the formula:
• ##STR30## wherein A together with ring B comprise a central group of the formula:
• ##STR31## wherein ring A.sup.12 is trans-1,4-disubstituted cyclohexane, trans-2,5-disubstituted 1,3-dioxane linked in the 2-position with ring B, or when ring B is trans-1,4-disubstituted cyclohexane or R.sup.2 is straight-chain alkyl of 1 to 7 carbon atoms, ring A.sup.12 also can be 1,4-phenylene or 2,5-disubstituted pyrimidine linked in the 2-position with ring B;
• ##STR32## wherein ring A.sup.1 is 1,4-phenylene, or trans-1,4-disubstituted cyclohexane;
• or ##STR33## wherein ring A.sup.2 is 1,4-phenylene or trans-1,4-disubstituted cyclohexane and E is --COO-- or --OOC--;
• ring B is 1,4-phenylene or trans-1,4- disubstituted cyclohexane;
• R.sup.1 is straight-chain alkyl of 1 to 9 carbon atoms or when R.sup.1 is attached to a benzene or a pyrimidine ring, R.sup.1 also is straight-chain alkoxy of 1 to 9 carbon atoms;
• and R.sup.2 is cyano or straight-chain alkyl of 1 to 7 carbon atoms.