Spiro[3.3] heptyl-dioxan derivatives and their use in liquid crystal media

A dioxane compound according to formula I;

• R1-(A1-Z1)m-G-(Z2-A2)n-R2 I
• in which
• G is
• R1 and R2 are each, independently of one another, identically or differently, H, halogen, —CN, —SCN, —NCS, —SF5, —SCF3, —CF3, —CF═CF2, —CF2CF2CF3, —OCF3, —OCHF2, —CF2CH2CF3, —OCH2CF2CHFCF3 or a linear or branched, optionally chiral alkyl or alkoxy radical having 1 to 15 C atoms which is unsubstituted, mono- or polysubstituted by halogen and in which one or more CH2 groups are each optionally replaced, independently of one another, by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —CH═CH—, —CH═CF—, —CF═CF—, —C≡C— or
• in such a way that heteroatoms are not linked directly to one another;
• A1 and A2 are each, independently of one another, identically or differently,
• a) trans-1,4-cyclohexylene, in which, in addition, one or more non-adjacent CH2 groups are each optionally replaced by —O— or —S— and in which, in addition, one or more H atoms are each optionally replaced by F,
• b) 1,4-phenylene, in which one or two CH groups are each optionally replaced by N and in which, in addition, one or more H atoms are each optionally replaced by halogen, —CN, —CH3, —CHF2, —CH2F, —CF3, —OCH3, —OCHF2 or —OCF3,
• c) bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro-[3.3]heptane-2,6-diyl, naphthalene-2,6-diyl, naphthalene-2,7-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, piperidine-1,4-diyl, phenanthrene-2,7-diyl, fluorene-2,7-diyl, anthracene-2,6-diyl, anthracene-2,7-diyl, or indane-2,5-diyl, where in each case one H atom or a plurality of H atoms are each optionally replaced by halogen,
• d) 1,4-cyclohexenylene or 1,3-cyclobutane-1,3-diyl;
• Z1 and Z2 are each, independently of one another, identically or differently, —O—, —CH2O—, —OCH2—, —CO—O—, —O—CO—, —CF2O—, —OCF2—, —CF2═CF2—, —CH2═CF2—, —CF2CH2—, —CH2CH2—, —CH═CH—, —CH═CF—, —CF═CH—, —CF═CF—, —CF═CF—COO—, —O—CO—CF═CF—, —C≡C—, —CH2CH2CF2O—, or a single bond;
• m is 0, 1, 2 or 3;
• and
• n is 1,2, or 3;
• wherein the Z2 bridge group attached to group G is a single bond.