Medium comprising one or more bimesogenic compounds, one or more nematogenic compound, one or more chiral compound and one or more compounds of formula I, R 11 -A 11 -(Z 12 -A 12) m -AG I in which, A 11 and A 12 each, independently of one another, denote an aryl-, heteroaryl-, heterocyclic- or alicyclic group optionally being substituted by one or more identical or different groups L, L in each case, independently of one another, denotes, halogen, -CN, -NO 2, -NCO, -NCS, -OCN, -SCN, straight-chain or branched alkyl or alkoxy having 1 to 5 C atoms, where, in addition, one or more non-terminal CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CF 2 O-, -CH=CH-, -O-, -CO-O-, -O-CO- in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, Z 12 in each case, independently of one another, denotes -O-,-S-, -CO-, -COO-, -OCO-, -S-CO-, -CO-S-, -O-COO-, -CO-NR 0 -, -NR 0 -CO-, -NR 0 -CO-NR 00, -NR 0 -CO-O-, -O-CO-NR 0 -, -OCH 2 -, -CH 2 O-, -SCH 2 -, -CH 2 S-, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -, -CH 2 CH 2 -, -(CH 2) 4 -, -CF 2 CH 2 -, -CH 2 CF 2 -, -CF 2 CF 2 -, -CH=N-, -N=CH-, -N=N-, -CH=CR 0 -, -CY 01 =CY 02 -, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, or a single bond, Y 01 and Y 02 each, independently of one another, denote H, F, Cl or CN. R 0 and R 00 each, independently of one another, denote H or alkyl having 1 to 12 C atoms, R 11 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more non-terminal CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CF 2 O-, -CH=CH-, -O-, -CO-O-, -O-CO- in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, AG denotes -Sp-X 11 Sp denotes -(CH 2) p -, p denotes 0, 1 or 2, X 11 denotes a group -NH 2, -SH, -OH, - OH or a group of the formulae or and m denotes 0, 1 or 2. A 11 and A 12 each, independently of one another, denote an aryl-, heteroaryl-, heterocyclic- or alicyclic group optionally being substituted by one or more identical or different groups L, L in each case, independently of one another, denotes, halogen, -CN, -NO 2, -NCO, -NCS, -OCN, -SCN, straight-chain or branched alkyl or alkoxy having 1 to 5 C atoms, where, in addition, one or more non-terminal CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CF 2 O-, -CH=CH-, -O-, -CO-O-, -O-CO- in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, Z 12 in each case, independently of one another, denotes -O-,-S-, -CO-, -COO-, -OCO-, -S-CO-, -CO-S-, -O-COO-, -CO-NR 0 -, -NR 0 -CO-, -NR 0 -CO-NR 00, -NR 0 -CO-O-, -O-CO-NR 0 -, -OCH 2 -, -CH 2 O-, -SCH 2 -, -CH 2 S-, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -, -CH 2 CH 2 -, -(CH 2) 4 -, -CF 2 CH 2 -, -CH 2 CF 2 -, -CF 2 CF 2 -, -CH=N-, -N=CH-, -N=N-, -CH=CR 0 -, -CY 01 =CY 02 -, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, or a single bond, Y 01 and Y 02 each, independently of one another, denote H, F, Cl or CN. R 0 and R 00 each, independently of one another, denote H or alkyl having 1 to 12 C atoms, R 11 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more non-terminal CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CF 2 O-, -CH=CH-, -O-, -CO-O-, -O-CO- in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, AG denotes -Sp-X 11 Sp denotes -(CH 2) p -, p denotes 0, 1 or 2, X 11 denotes a group -NH 2, -SH, -OH, - OH or a group of the formulae or and m denotes 0, 1 or 2.