Chiral dopants

A liquid crystalline material comprising at least one chiral dopant of formula I:

• R1—X1—MG1—G—MG2—X2—R2
• wherein
• R1 and R2 are each independently a straight-chain or branched alkyl radical with up 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 CH2 groups to be replaced, in each case independently from one another, by —O—, —S—, —NH—, —N(CH3)—, —CO—, —COO—, —OCO—, —OCO— O—, —S—CO—, —CO—S— or —C≡C— in such a manner that oxygen atoms are not linked directly to one another,
• X1 and X2 are independently of each other —O—, —S—, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S— or a single bond,
• G is the following structure element
• MG1 and MG2 are each independently a mesogenic or mesogenity supporting group of the formula:
• —(A1—Z)m—A2—
• with
• Z denoting —COO—, —OCO—, —CH2CH2—, —OCH2—, —CH2O—, —CH═CH—, —CH═CH—COO—, —OCO—CH═CH—, —C≡C— or a single bond,
• A1 and A2 being each independently 1,4-phenylene in which, in addition, one or more CH groups may be replaced by N, 1,4-yclohexylene in which, in addition, one or two non-adjacent CH2 groups may be replaced by O and/or S, 1,4-cyclohexenylene, 1,4-bicyclo(2,2,2)octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, or 1,2,3,4-tetrahydronaphthalene-2,6-diyl, it being possible for all these groups to be unsubstituted, mono- or polysubstituted with halogen, cyano or nitro groups or alkyl, alkoxy or alkanoyl groups having 1 to 7 C atoms wherein one or more H atoms may be substituted by F or Cl, and
• m being 0, 1, 2 or 3
• and at least one polymerizable mesogenic compound having at least one polymerizable functional group.

A polymer film with a chiral liquid crystalline phase comprising at least one chiral dopant of formula I

• R1—X1—MG1—G—MG2—X2—R2
• wherein
• R1 and R2 are each independently a straight-chain or branched alkyl radical with up 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 CH2 groups to be replaced, in each case independently form one another, by —O—, —S—, —NH—, —N(CH3)—, —CO—, —COO—, —OCO—, —OCO— O—, —S—CO—, —CO—S— or —C≡C— in such a manner that oxygen atoms are not linked directly to one another,
• X1 and X2 are independently of each other —O—, —S—, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S— or a single bond,
• G is the following structure element
• MG1 and MG2 are each independently a mesogenic or mesogenity supporting group of the formula
• —(A1—Z)m—A2—
• with
• Z denoting —COO—, —OCO—, —CH2CH2—, —OCH2—, —CH2O—, —CH═CH—, —CH═CH—COO—, —OCO—CH═CH—, —C≡C— or a single bond,
• A1 and A2 being each independently 1,4-phenylene in which, in addition, one or more CH groups may be replaced by N, 1,4-cyclohexylene in which, in addition, one ore two non-adjacent CH2 groups may be replaced by O and/or S, 1,4-cyclohexenylene, 1,4-bicyclo(2,2,2)octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, or 1,2,3,4-tetrahydronaphthalene-2,6-diyl, it being possible for all these groups to be unsubstituted, mono- or polysubstituted with halogen, cyano or nitro groups or alkyl, alkoxy or alkanoyl groups having 1 to 7 C atoms wherein one or more H atoms may be substituted by F or l, and
• m being 0, 1, 2 or 3.