Liquid crystals comprising cyclopentane groups

A compound having the formula:

• wherein
• R is selected from the group consisting of H and unsubstituted or substituted alkyl each having 1-12 carbon atoms wherein the substitutions are independently one or more of halogen or CN, wherein one or more —CH2— groups of the alkyl groups may independently be replaced with —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— or —CH═CH—, provided that heteroatoms are not connected directly, except as permitted in the listed groups;
• A and B are each independently selected from the group consisting of:
• 1,4-cyclohexyl, in which one —CH2— or two not directly linked —CH2— can be replaced by O or S;
• 1,4-cyclohexenyl;
• piperidine-1,4-diyl;
• 1,4-bicyclo[2,2,2]octylene;
• 1,4-phenyl, which may be substituted with one or more halogens;
• Pyridin-5,2-dyl;
• pyrimidin-5,2-diyl;
• naphthalene-2,6-diyl;
• trans-decahydronaphthalene-2,6-diyl;
• tetrahydronaphthalene-2,6-diyl;
• indane;
• indene;
• phenanthryl;
• and dibenzofuran, which may each independently in each instance be independently substituted with one or more halogens and/or one or more X1-X4 substitutents;
• Z1 is a single bond or C1-7 unsubstituted or substituted alkylene, wherein the substitutions are independently one or more of halogen or CN, wherein one or more —CH2— groups of the alkyl groups may each independently be replaced by —O—, —S—, —CO—O—, —O—CO—, —O—CO—O— or —CH═CH— provided that heteroatoms are not connected directly to each other except as permitted in the listed groups;
• Z2 and Z3 are each independently selected from the group consisting of:
• a single bond, —(CH2)2—, —(CH2)4—, —CH═CHCH2CH2—, —CH2CH2CH═CH—, —CF2O—, —OCF2—, —CF2CF2—, —CF═CF—, —CH2CF2—, —CF2CH2—, —OCF2CF2O—, —C2H4CF2O—, —CH2CF2OCH2—, —CH2OCF2CH2—, —OCF2C2H4—, —C3H6O—, —OC3H6—, —C2H4OCH2—, —CH2OC2H4—, —CH2O—, —OCH2—, —CH═CH—, —C≡C—, and —COO—;
• n, m and K are each independently 0, 1, or 2, and m+K+n≧2;
• X1, X2, X3, and X4 are each independently selected from the group consisting of:
• H, F, Cl, CF3, CH F2, OCF3, OCF2H and CN;
• Y is independently selected from the group consisting of:
• —H, —F, —Cl, —CN, —NCS, —OCHF2, —CHF2, —OCF3, —OCF2CF3, —CF3, C1-20 alkyl, C1-20 alkoxy, C1-20 alkenyl, and C1-20 alkenyloxy, wherein the alkyl, alkoxy, alkenyl, and alkenyloxy groups may be independently substituted by one or more halogens;
• wherein one or more hydrogen atoms in Formula I may be replaced with deuterium;
• provided that when R═H and Y has less than 2 carbon atoms and X3, X4 are H or when R═H and Y has two or more carbon atoms and Z1 has more than 3 carbon atoms, there must be a fused ring system present in the compound or one of Z1, Z2 and Z3 must be selected from the group consisting of:
• C1-C3 alkylene, —CH═CHCH2CH2—, —CH2CH2CH═CH—, —CF2O—, —OCF2—, —CF2CF2—, —CF═CF—, —CH2CF2—, —CF2CH2—, —OCF2CF2O—, —C2H4CF2O—, —CH2CF2OCH2—, —CH2OCF2CH2—, —OCF2C2H4—, —C3H6O—, —OC3H6—, —C2H4OCH2—, —CH2OC2H4—, and —CH═CH—;
• and provided that when R is not H and Y does not contain a —CF2— group, either one of A and B is selected from the group consisting of:
• 1,4-cyclohexene, in which one or two not directly linked —CH2— groups are optionally replaced by —O— or —S—;
• Pyridin-5,2-diyl;
• pyrimidin-5,2-diyl;
• indane;
• indene;
• phenanthryl, and dibenzofuran;
• or one of Z1, Z2 and Z3 must be selected from the group consisting of:
• —(CH2)4—, —CH═CHCH2CH2—, —CH2CH2CH═CH—, —CF2O—, —OCF2—, —CF2CF2—, —CF═CF—, —CH2CF2—, —CF2CH2—, —OCF2CF2O—, —C2H4CF2O—, —CH2CF2OCH2—, —CH2OCF2CH2—, —OCF2C2H4—, —C3H6O—, —OC3H6—, —C2H4OCH2—, —CH2OC2H4—, —CH═CH—, and —C≡C—.