Compounds having a C—C triple bond and use thereof in liquid-crystal mixtures

A compound of the formula I

• R1-[A1-Z1]m-A2A3-[Z2-A4]n-[Z3-A5]o-R2 I
• in which
• one of A2 and A3 denotes
• the other of A2 and A3, A1, A4 and A5,
• independently of one another, denote
• a) 1,4-phenylene, in which one or more CH groups may be replaced by N, or
• b) a radical of the formula
• and in which, in the groups a) and b),
• one or more H atoms are optionally replaced, independently, by in each case a group Y,
• Y denotes Br, Cl, F, CN, —NCS, —SCN, SF5, C2-C10 alkenyl, C1-C10 alkoxy, C3-C6 cycloalkyl, C3-C6 cycloalkenyl or a mono- or polyfluorinated C1-C10 alkyl or alkoxy group,
• R1 and R2, independently of one another, denote a straight-chain alkyl radical having 1 to 15 C atoms, where, in addition, one or more CH2 groups in these radicals may each be replaced, independently of one another, by —C≡C—, —CH═CH—, —(CO)O—, —O(CO)—, —(CO)—, or —O— in such a way that O atoms are not linked directly to one another,
• R3 denotes C1-C10 alkyl, C2-C10 alkenyl, C1-C10 alkoxy, C3-C6 cycloalkyl, C3-C6 cycloalkenyl or a mono- or polyfluorinated C1-C10 alkyl or alkoxy group,
• Z1, Z2 and Z3, independently of one another, denote a single bond, and
• m is 0, n and o are 1, where (m+n+o) is 2.