Compounds of formula I wherein R 11 and R 12 are each independently H, F, Cl, CN, NCS or a straight-chain or branched alkyl group with 1 to 25 C atoms which may be unsubstituted, mono- or polysubstituted by halogen or CN, it being also possible for one or more non-adjacent CH 2 groups to be replaced, in each occurrence independently from one another, by -O-, -S-, -NH-, -N(CH 3)-, -CO-, -COO-, -OCO-, -O-CO-O-, -S-CO-, -CO-S-, -CH=CH-, -CH=CF-, -CF=CF- or -C≡C-in such a manner that oxygen atoms are not linked directly to one another, preferably a polar group, more preferably F, Cl, CN, OCF 3, CF 3, MG 11 and MG 12 are each independently a group, which is 6-atomic ring or comprises one, two or more 6-atomic rings, in case of comprising two or more 6-atomic rings at least two of these may be linked by a 2-atomic linking group, and wherein additionally. MG 11 is a or comprises one 1,3-phenylene, wherein optionally one or two non-adjacent CH groups each may be replaced by an N-atom, and which optionally is substituted by one or more halogen atoms and/or by one or more alkyl group(s) each independently having 1 to 9 C atoms and/or by one more alkoxy group(s) each independently having 1 to 9 C atoms, Sp 1 is a spacer group comprising 1, 2, 3, 4 or 5 to 40 C atoms, wherein one or more non-adjacent and non-terminal CH 2 groups may also be replaced by -O-, -S-, -NH-, -N(CH 3)-, -CO-, -O-CO-, -S-CO-, -O-COO-, -CO-S-, -CO-O-, -CH(halogen)-, -CH -, -CH=CH- or -C≡C-, however in such a way that no two O-atoms are adjacent to one another, now two -CH=CH- groups are adjacent to each other and no two groups selected from -O-CO-, -S-CO-, -O-COO-, -CO-S-, -CO-O- and -CH=CH- are adjacent to each other, wherein one or more H atoms in -(CH 2) n - may independently of each other optionally be replaced by F or CH 3 and/or one or more non-adjacent -CH 2 - groups may be replaced by -O-, and X 11 and X 12 are each independently of one another a group selected from -CH=CH-, -C≡C-, -O-, -CF 2 -O-, -O-CF 2 -, -CO-O-, -O-CO-, -O-CO-O-, -S-, -CS- S-, -S-CS-, -CO-S-, -S-CO-, -S-CO-S- and -S-CS-S- or a single bond, however, under the condition that in -X 11 -Sp 1 -X 12 - no two O-atoms are adjacent to one another, now two -CH=CH- groups are adjacent to each other and no two groups selected from -O-CO-, -S-CO-, -O-COO-, -CO-S-, -CO-O- and -CH=CH- are adjacent to each other. R 11 and R 12 are each independently H, F, Cl, CN, NCS or a straight-chain or branched alkyl group with 1 to 25 C atoms which may be unsubstituted, mono- or polysubstituted by halogen or CN, it being also possible for one or more non-adjacent CH 2 groups to be replaced, in each occurrence independently from one another, by -O-, -S-, -NH-, -N(CH 3)-, -CO-, -COO-, -OCO-, -O-CO-O-, -S-CO-, -CO-S-, -CH=CH-, -CH=CF-, -CF=CF- or -C≡C-in such a manner that oxygen atoms are not linked directly to one another, preferably a polar group, more preferably F, Cl, CN, OCF 3, CF 3, MG 11 and MG 12 are each independently a group, which is 6-atomic ring or comprises one, two or more 6-atomic rings, in case of comprising two or more 6-atomic rings at least two of these may be linked by a 2-atomic linking group, and wherein additionally. MG 11 is a or comprises one 1,3-phenylene, wherein optionally one or two non-adjacent CH groups each may be replaced by an N-atom, and which optionally is substituted by one or more halogen atoms and/or by one or more alkyl group(s) each independently having 1 to 9 C atoms and/or by one more alkoxy group(s) each independently having 1 to 9 C atoms, Sp 1 is a spacer group comprising 1, 2, 3, 4 or 5 to 40 C atoms, wherein one or more non-adjacent and non-terminal CH 2 groups may also be replaced by -O-, -S-, -NH-, -N(CH 3)-, -CO-, -O-CO-, -S-CO-, -O-COO-, -CO-S-, -CO-O-, -CH(halogen)-, -CH -, -CH=CH- or -C≡C-, however in such a way that no two O-atoms are adjacent to one another, now two -CH=CH- groups are adjacent to each other and no two groups selected from -O-CO-, -S-CO-, -O-COO-, -CO-S-, -CO-O- and -CH=CH- are adjacent to each other, wherein one or more H atoms in -(CH 2) n - may independently of each other optionally be replaced by F or CH 3 and/or one or more non-adjacent -CH 2 - groups may be replaced by -O-, and X 11 and X 12 are each independently of one another a group selected from -CH=CH-, -C≡C-, -O-, -CF 2 -O-, -O-CF 2 -, -CO-O-, -O-CO-, -O-CO-O-, -S-, -CS- S-, -S-CS-, -CO-S-, -S-CO-, -S-CO-S- and -S-CS-S- or a single bond, however, under the condition that in -X 11 -Sp 1 -X 12 - no two O-atoms are adjacent to one another, now two -CH=CH- groups are adjacent to each other and no two groups selected from -O-CO-, -S-CO-, -O-COO-, -CO-S-, -CO-O- and -CH=CH- are adjacent to each other.