Compounds and liquid-crystalline medium

A compound according to formula I

• in which
• n denotes an integer from 1 to 4,
• m denotes (4−n),
• denotes an organic radical having 4 bonding sites,
• Z11 and Z12, independently of one another, denote —O—, —(C═O)—, —(N—R14)— or a single bond, but do not both simultaneously denote —O—,
• r and s, independently of one another, denote 0 or 1,
• Y11 to Y14 each, independently of one another, denote alkyl having 1 to 4 C atoms, or alternatively, independently from each other, the two pairs (Y11 and Y12) and (Y13 and Y14) may be connected by a bond to form together a divalent group having 3 to 6 C-atoms
• R11 denotes O—R13, O• or OH, preferably O—R13 or O•, particularly preferably O•, isopropoxy, cyclohexyloxy, acetophenoxy or benzoxy and very particularly preferably O•,
• R12 on each occurrence, independently of one another, denotes H, F, OR14, NR14R15, a straight-chain or branched alkyl chain having 1-20 C atoms, in which one —CH2— group or a plurality of —CH2— groups may each be replaced by —O— or —C(═O)—, but two adjacent —CH2— groups cannot be replaced by —O—, or denotes a hydrocarbon radical which contains a cycloalkyl or alkylcycloalkyl unit, and in which one —CH2— group or a plurality of —CH2— groups may each be replaced by —O— or —C(═O)—, but two adjacent —CH2— groups cannot be replaced by —O—, and in which one H atom or a plurality of H atoms may each be replaced by OR14, N(R14)(R15) or R16, or denotes an aromatic or heteroaromatic hydrocarbon radical, in which one H atom or a plurality of H atoms may each be replaced by OR14, N(R14)(R15) or R16,
• R13 on each occurrence, independently of one another, denotes a straight-chain or branched alkyl chain having 1-20 C atoms, in which one —CH2— group or a plurality of —CH2— groups may each be replaced by —O— or —C(═O)—, but two adjacent —CH2— groups cannot be replaced by —O—, or denotes a hydrocarbon radical which contains a cycloalkyl or alkylcycloalkyl unit, and in which one —CH2— group or a plurality of —CH2— groups may each be replaced by —O— or —C(═O)—, but two adjacent —CH2— groups cannot be replaced by —O—, and in which one H atom or a plurality of H atoms may each be replaced by OR14, N(R14)(R15) or R16, or denotes an aromatic or heteroaromatic hydrocarbon radical, in which one H atom or a plurality of H atoms may each be replaced by OR14, N(R14)(R15) or R16,
• or can be
• (1,4-cyclohexyl), in which one or more —CH2— groups may be replaced by —O—, —CO— or —NR14—, or an acetophenyl, isopropyl or 3-heptyl radical,
• R14 on each occurrence, independently of one another, denotes a straight-chain or branched alkyl or acyl group having 1 to 10 C atoms or an aromatic hydrocarbon or carboxyl radical having 6-12 C atoms,
• R15 on each occurrence, independently of one another, denotes a straight-chain or branched alkyl or acyl group having 1 to 10 C atoms or an aromatic hydrocarbon or carboxyl radical having 6-12 C atoms,
• R16 on each occurrence, independently of one another, denotes a straight-chain or branched alkyl group having 1 to 10 C atoms, in which one —CH2— group or a plurality of —CH2— groups may each be replaced by —O— or —C(═O)—, but two adjacent —CH2— groups cannot be replaced by —O—,
• with the provisos that,
• (i) in the case where n=1, R11=O•, and
• —[Z11—]r—[Z12]s—=—O—, —(CO)—O—, —O—(CO)—, —O—(CO)—O—, NR14— or —NR14—(CO)—, then
• does not denote
• straight-chain or branched alkyl having 1 to 10 C atoms, also cycloalkyl, cycloalkylalkyl or alkylcycloalkyl, where one or more —CH2— groups in all these groups may be replaced by —O— in such a way that two O atoms in the molecule are not bonded directly to one another,
• (ii) in the case where n=2 and R11=O•, then
• does not denote
• and
• (iii) in the case where n=2 and R11=O—R13, then
• R13 does not denote n-C1-9-alkyl,