Alkyl silane liquid crystal compounds

A liquid crystal composition comprising one or more compounds of formula;

• wherein D is:
• where:
• R1 is an alkyl or alkenyl group having j carbon atoms and R2, R2′, R3 and R3′, independently of one another, are alkyl groups having from 1-6 carbon atoms;
• n1 and m are integers from 1 to about 20;
• X is oxygen or a single bond;
• and
• j is an integer from 1 to 18;
• and
• wherein a, b, x, y, z can be 0 or 1;
• x+y+z is 1, 2 or 3, when x is 0, a is 0;
• when z is 0, b is 0;
• A and B, independently, when present, can be —O—, —COO—, —OOC—, —CH2—CH2—, —CH═CH—, —C≡C—, —CH═CH—CH═CH—, —O—CH2— or —CH2—O;
• the A, B and C rings, independently of one another, are aromatic rings or alicyclic rings, where one or two carbons in the A, B or C rings that are aromatic can be replaced with a N, O or S and one or two of the carbons in the A, B or C rings that are alicylic can be replaced with a N, O or S or a C═O group;
• provided that the A, B or C rings are not a 3,4-difluopropyridine ring;
• Y can represent up to four substituents on aromatic rings and up to 10 substituents on an alicyclic ring where Y can a halogen, CN group, NO2, alkyl or alkoxy;
• Z is a single bond, an —O— or a —COO— or —OOC— group, and
• M is a tail group which can be:
• a non-fluorinated alkyl, or other group or RF.
• where RF is an alkyl, or ether group which is fully or partially fluorinated.

A LC compound having the formula:

• where D is:
• where:
• R1 is an alkyl or alkenyl group having j carbon atoms and R2, R2′, R3 and R3′, independently of one another, are alkyl groups having from 1-6 carbon atoms;
• n1 and m are integers from 1 to about 20;
• X is oxygen or a single bond;
• and
• j is an integer from 1 to 18;
• and
• wherein a, b, x, y, z can be 0 or 1;
• x+y+z is 1, 2 or 3, when x is 0, a is 0;
• when z is 0, b is 0;
• A and B, independently, when present, can be —O—, —COO—, —OOC—, —CH2—CH2—, —CH═CH—, —C≡C—, —CH═CH—CH═CH—, —O—CH2— or —CH2—O;
• the A, B and C rings, independently of one another, are aromatic rings or alicyclic rings, where one or two carbons in the A, B or C rings that are aromatic can be replaced with a N, O or S and one or two of the carbons in the A, B or C rings that are alicylic can be replaced with a N, O or S or a C═O group;
• provided that the A, B or C rings are not a 3,4-difluorppyridine ring;
• Y can represent up to four substituents on aromatic rings and up to 10 substituents on an alicyclic ring where Y can a halogen, CN group, NO2, alkyl or alkoxy;
• Z is a single bond, an —O— or a —COO— or —OOC— group, and
• M is RF, where RF is a straight-chain or branched alkyl or ether group which is fully or partially fluorinated and contains up to 20 carbon atoms.