Compounds of the formula (I) are described in which M1 is, for example, —CO—O— or a single bond A1 is, for example, 1,4-phenylene, R5 has the same possible definitions specified for R1, with the exception of -M1-A1-R5, but independently of the definition of R1 G1-G2 is CH2CH2, CH═CH, CF2CF2, CF═CF, CF═CH, CH═CF X1, X2, X3, X4, X5 are each independently H or F R1, Y1, Y2 are each independently a) H b) F where Y1, R1, (R1 and Y1) or (R1 and Y2) may also have the definitions c) and/or d), but only in each case not more than one of (R1 and Y1) and of (R1 and Y2) may have the definition d) c) is, for example, a straight-chain or branched alkyl radical having from 1 to 16 carbon atoms or a straight-chain or branched alkenyl radical having from 2 to 16 carbon atoms, d) -M1-A1-R5 with the following provisos: a) at least one of X1, X2, X3, X4, X5, G1-G2 is or contains F b1) when at least one of Y1 and X1 is F and/or G1-G2 contains F, it is possible for R1, X2, X3, X4 not to be F b2) when at least one of R1, X2, X3, X4 is F, it is possible for X1 and Y1 not to be F, and for G1-G2 to be CH2CH2 or CH═CH c) it is not possible for Y2 and X5 simultaneously to be F.