Liquid crystal composition containing dibenzo derivative and liquid crystal display device

A larger elastic constant and/or higher transmittance liquid crystal composition containing a dibenzo derivative, comprising at least one compound of general formula I and at least one compound of general formula II:

• wherein
• R represents —H, halogen, —CN, straight alkyl containing 1 to 12 carbon atoms, branched alkyl containing 3 to 12 carbon atoms,
• wherein one or at least two non-adjacent —CH2— in the straight alkyl containing 1 to 12 carbon atoms, the branched alkyl containing 3 to 12 carbon atoms,
• may be respectively and independently substituted by —CH═CH—, —C≡C—, —O—, —S—, —CO—, —CO—O— or —O—CO—, and one or at least two —H in the straight alkyl containing 1 to 12 carbon atoms, the branched alkyl containing 3 to 12 carbon atoms,
• may be respectively and independently substituted by —F or —Cl;
• Rx represents —H, straight alkyl containing 1 to 12 carbon atoms, or branched alkyl containing 3 to 12 carbon atoms, wherein one or at least two non-adjacent —CH2— in the straight alkyl containing 1 to 12 carbon atoms or the branched alkyl containing 3 to 12 carbon atoms may be respectively and independently substituted by —CH═CH—, —C≡C—, —O—, —S—, —CO—, —CO—O— or —O—CO—, one or at least two —H in the straight alkyl containing 1 to 12 carbon atoms or the branched alkyl containing 3 to 12 carbon atoms may be respectively and independently substituted by —F or —Cl and Rx is attached to an arbitrary carbon atom in the ring
• R1 and R2 each independently represents straight alkyl containing 1 to 12 carbon atoms, branched alkyl containing 3 to 12 carbon atoms,
• wherein one or at least two non-adjacent —CH2— in the straight alkyl containing 1 to 12 carbon atoms or the branched alkyl containing 3 to 12 carbon atoms may be respectively and independently substituted by —CH═CH—, —C≡C—, —O—, —S—, —CO—, —CO—O— or —O—CO—, one or at least two —H in the straight alkyl containing 1 to 12 carbon atoms or the branched alkyl containing 3 to 12 carbon atoms may be respectively and independently substituted by —F or —Cl, and R1 and R2 are each attached to an oxygen atom in general formula II via a carbon atom;
• the ring
• represents
• wherein one or at least two intra-ring single bonds in the ring
• is substituted by a double bond(s):
• or the ring
• represents
• wherein one or at least two intra-ring single bonds in the ring
• is optionally substituted by a double bond(s);
• the ring
• represents
• wherein in
• one or at least two —CH2— may be substituted by —O—, and one or at most two intra-ring single bonds may be substituted by a double bond(s);
• and in
• one or at least two —H may be substituted by a —F or —Cl, and one or at least two intra-ring —CH═ may be substituted by a —N═;
• the ring
• represents
• wherein in
• one or at least two —H may be substituted be a —F or —Cl, and one or at least two intra-ring —CH═ may be substituted by —N═;
• Z1 represents —(CH2)aO— or —(CH2)aS—, wherein a represents an integer from 0 to 7;
• Z2 represents —O—, —S—, —CO—O—, —O—CO—, —CF2O—, —OCF2O—, —CH2O—, —CH2S—, —OCH2—, —SCH2—, —CH2—, —CH2CH2—, —(CH2)4—, —CH═CH—CH2O—, —C2F4——CH2CF2—, —CF2CH2—, —CF═CF—, —CH═CF—, —CF═CH—, —CH═CH—, —C≡C— or a single bond;
• L1 and L2 each independently represents —F, —Cl, —CF3 or —CHF2;
• X represents —CO—, —S— or —O—;
• n represents 0, 1 or 2, wherein when n represents 2, the ring
• is the same or different, and Z2 is the same or different;
• and
• m represents 0, 1 or 2, wherein when m represents 2, the ring
• is the same or different;
• the liquid crystal composition further comprises one or at least two compounds of general formula M, wherein the compound of general formula M is selected from the group consisting of the following compounds:
• wherein
• RM1 and RM2 each independently represents straight alkyl containing 1 to 12 carbon atoms, branched alkyl containing 3 to 12 carbon atoms,
• wherein one or at least two non-adjacent —CH2— in the straight alkyl containing 1 to 12 carbon atoms or the branched alkyl containing 3 to 12 carbon atoms may be respectively and independently substituted by —CH═CH—, —C≡C—, —O—, —CO—, —CO—O—O— or —O—CO—.