Mesogenic dimers

1. A compound comprising two subunits, wherein each subunit comprises

two mesogenic groups comprising one or more non-aromatic rings,

optionally one or more polymerizable groups attached to at least one of the mesogenic groups either directly or via spacer groups, and

a bridging group connecting the mesogenic groups, comprising one or more subgroups selected from pi-conjugated linear carbyl or hydrocarbyl groups, aromatic and heteroaromatic groups, and being linked to a sp 3 -hybridized C atom or Si-atom in a non-aromatic ring of each mesogenic group.

2. A compound according to claim 1 , wherein said mesogenic groups comprise more saturated rings than unsaturated or aromatic rings.

3. A compound according to claim 1 , wherein said bridging group consists of subgroups selected from pi-conjugated linear groups, aromatic and heteroaromatic groups.

4. A compound according to claim 1 , wherein said bridging group is connected in axial position to a cyclohexylene or silanane ring comprised in a mesogenic group, which is optionally substituted and wherein one or more non-adjacent C-atoms are each optionally replaced by Si and/or one or more non-adjacent CH 2 groups are each optionally replaced by —O— or —S—.

5. A compound according to claim 1 , selected from the following formula:

wherein

W is a spacer group,

U 1,2 are independently of each other selected from

including their mirror images, wherein the rings U 1 and U 2 are each bonded to the group —(B) q — via the axial bond, and one or two non-adjacent CH 2 groups in these rings are each optionally replaced by O or S, and the rings U 1 and U 2 are each optionally substituted by one or more groups L,

Q 1,2 are, independently of each other, CH or SiH,

Q 3 is C or Si,

B is in each occurrence independently of one another —C≡C—, —CY 1 ═CY 2 — or an optionally substituted aromatic or heteroaromatic group,

Y 1,2 are independently of each other H, F, Cl, CN or R 0 ,

q is an integer from 1 to 10,

A 1-4 are independently of each other selected from non-aromatic, aromatic or heteroaromatic carbocylic or heterocyclic groups, which are optionally substituted by one or more groups R 5 , and wherein each of -(A 1 -Z 1 ) m —U 1 —(Z 2 -A 2 ) n - and -(A 3 -Z 3 ) o —U 2 —(Z 4 -A 4 ) p - does not contain more aromatic groups than non-aromatic groups,

Z 1-4 are independently of each other, identical or different groups selected from —O—, —S—, —CO—, —COO—, —OCO—, —O—COO—, —CO—NR 0 —, —NR 0 —CO—, —NR 0 —CO—NR 0 —, —OCH 2 —, —CH 2 O—, —SCH 2 —, —CH 2 S—, —CF 2 O—, —OCF 2 —, —SCF 2 —, —CH 2 CH 2 —, —(CH 2 ) 3 —, —(CH 2 ) 4 —, —CF 2 CH 2 —, —CH 2 CF 2 —, —CF 2 CF 2 —, —CH═CH—, —CY 1 ═CY 2 —, —CH═N—, —N═CH—, —N═N—, —CH═CR 0 —, —C≡C—, —CH═CH—COO—, —OCO—CH═CH—, CR 0 R 00 or a single bond,

R 0 and R 00 are independently of each other H or alkyl with 1 to 12 C-atoms,

m, n, o and p are independently of each other 0, 1, 2, 3 or 4,

R 1-5 are, independently of each other, identical or different groups selected from H, halogen, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(═O)NR 0 R 00 , —C(═O)X 0 , —C(═O)R 0 , —NH 2 , —NR 0 R 00 , —SH, —SR 0 , —SO 3 H, —SO 2 R 0 , —OH, —NO 2 , —CF 3 , —SF 5 , P-Sp-, optionally substituted silyl, or carbyl or hydrocarbyl with 1 to 40 C atoms that is optionally substituted and optionally comprises one or more hetero atoms, or denote P or P-Sp-, or are substituted by P or P-Sp-, wherein the compounds comprise at least one group R 1-5 denoting or being substituted by P or P-Sp-,

P is a polymerizable group, and

Sp is a spacer group or a single bond.

6. A compound according to claim 5 , wherein the bridging group —(B) q — is selected from —C≡C—, —C≡C—C≡C—, —C≡C—C≡C—C≡C—, —C≡C—C≡C—C≡C—C≡C—,

wherein

r is 0, 1, 2, 3 or 4,

L is selected from P-Sp-, F, Cl, Br, I, —CN, —NO 2 , —NCO, —NCS, —OCN, —SCN, —C(═O)NR 0 R 00 , —C(═O)X, —C(═O)OR 0 , C(═O)R 0 , —NR 0 R 00 , —OH, —SF 5 , optionally substituted silyl, aryl with up to 12 C atoms, and straight chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy with up to 12 C atoms, wherein in the alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy groups one or more H atoms are optionally replaced by F or Cl, and

X is halogen.

7. A compound according to claim 5 , wherein U 1 and U 2 are selected from

8. A compound according to claim 6 , wherein A 1-4 are selected from trans-1,4-cyclohexylene and 1,4-phenylene that is optionally substituted with one or more groups.

9. A compound according to claim 1 , wherein the mesogenic groups do not comprise more than one unsaturated or aromatic ring.

10. A compound according to claim 5 , wherein Z 1-4 are selected from —O—, —S—, —CO—, —COO—, —OCO—, —O—COO—, —CO—NR 0 —, —NR 0 —CO—, —NR 0 —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 ) 3 —, —(CH 2 ) 4 —, —CF 2 CH 2 —, —CH 2 CF 2 —, —CF 2 CF 2 —, —CH═CH—, —CY 1 ═CY 2 —, —CH═N—, —N═CH—, —N═N—, —CH═CR 0 —, —C≡C—, —CH═CH—COO—, —OCO—CH═CH—, CR 0 R 00 or a single bond.

11. A compound according to claim 5 , wherein

P is selected from CH 2 ═CW 1 —COO—, CH 2 ═CW 1 —CO—,

CH 2 ═CW 2 —(O) k1 —, CH 3 —CH═CH—O—, (CH 2 ═CH) 2 CH—OCO—, (CH 2 ═CH—CH 2 ) 2 CH—OCO—, (CH 2 ═CH) 2 CH—O—, (CH 2 ═CH—CH 2 ) 2 N—, (CH 2 ═CH—CH 2 ) 2 N—CO—, HO—CW 2 W 3 —, HS—CW 2 W 3 —, HW 2 N—, HO—CW 2 W 3 —NH—, CH 2 ═CW 1 —CO—NH—, CH 2 ═CH—(COO) k1 -Phe-(O) k2 —, CH 2 ═CH—(CO) k1 -Phe-(O) k2 —, Phe-CH═CH—, HOOC—, OCN—, and W 4 W 5 W 6 Si—,

W 1 is H, F, Cl, CN, CF 3 , phenyl or alkyl with 1 to 5 C-atoms,

W 2 and W 3 are, independently of each other, H or alkyl with 1 to 5 C-atoms,

W 4 , W 5 and W 6 are, independently of each other, Cl, oxaalkyl or oxacarbonylalkyl with 1 to 5 C-atoms,

W 7 and W 8 are, independently of each other, H, Cl or alkyl with 1 to 5 C-atoms,

Phe is 1,4-phenylene that is optionally substituted, and

k 1 and k 2 are, independently of each other, 0 or 1.

12. A compound according to claim 5 , wherein

W is selected from formula X′—W′—X″,

W′ is alkylene with 1 to 20 C atoms, preferably 1 to 12 C-atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, and wherein one or more non-adjacent CH 2 groups are optionally replaced, in each case independently from one another, by —O—, —S—, —NH—, —NR 0 —, —SiR 0 R 00 —, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S—, —NR 0 —CO—O—, —O—CO—NR 0 —, —NR 0 —CO—NR 0 —, —CH═CH— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, and

X′ and X″ are, independently of each other, —O—, —S—, —CO—, —COO—, —OCO—, —O—COO—, —CO—NR 0 —, —NR 0 —CO—, —NR 0 —CO—NR 0 —, —OCH 2 —, —CH 2 O—, —SCH 2 —, —CH 2 S—, —CF 2 O—, —OCF 2 —, —CF 2 S—, —SCF 2 —, —CF 2 CH 2 —, —CH 2 CF 2 —, —CF 2 CF 2 —, —CH═N—, —N═CH—, —N═N—, —CH═CR 0 —, —CY 1 ═CY 2 —, —C≡C—, —CH═CH—COO—, —OCO—CH═CH— or a single bond.

13. A compound according to claim 12 , wherein

Sp is of the formula Sp′-X′ whereby P-Sp- is P-Sp′-X′—, and

Sp′ is alkylene with 1 to 20 C atoms, preferably 1 to 12 C-atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, and wherein one or more non-adjacent CH 2 groups are optionally replaced, in each case independently from one another, by —O—, —S—, —NH—, —NR 0 —, —SiR 0 R 00 —, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S—, —NR 0 —CO—O—, —O—CO—NR 0 —, —NR 0 —CO—NR 0 —, —CH═CH— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another.

14. A compound according to claim 6 , selected from the following formulae:

15. A compound according to claim 5 , selected from the following formulae:

wherein

Z is selected from —O—, —S—, —CO—, —COO—, —OCO—, —O—COO—, —CO—NR 0 —, —NR 0 —CO—, —NR 0 —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 ) 3 —, —(CH 2 ) 4 —, —CF 2 CH 2 —, —CH 2 CF 2 —, —CF 2 CF 2 —, CH═CH—, —CY 1 ═CY 2 —, —CH═N—, —N═CH—, —N═N—, —CH═CR 0 —, —C≡C—, —CH═CH—COO—, —OCO—CH═CH—, CR 0 R 00 or a single bond, and

R is selected from H, halogen, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(═O)NR 0 R 00 , —C(═O)X 0 , —C(═O)R 0 , —NH 2 , —NR 0 R 00 , —SH, —SR 0 , —SO 3 H, —SO 2 R 0 , —OH, —NO 2 —CF 3 , —SF 5 , P-Sp-, optionally substituted silyl, or carbyl or hydrocarbyl with 1 to 40 C atoms that is optionally substituted and optionally comprises one or more hetero atoms.

16. A liquid-crystal formulation comprising one or more compounds according to claim 1 .

17. A polymerizable liquid-crystal formulation comprising one or more compounds according to claim 1 , and one or more further compounds, wherein at least one of the compounds is polymerizable.

18. A birefringent polymer film obtainable by polymerizing a polymerizable compound according to claim 1 in its liquid-crystal phase in an oriented state in the form of a thin film.

19. A birefringent polymer film with R 450 /R 550 <1, wherein R 450 is the optical on-axis retardation at a wavelength of 450 nm and R 550 is the optical on-axis retardation at a wavelength of 550 nm, said film being obtainable by polymerizing one or more polymerizable compounds according to claim 1 .

20. An optical film, retarder, or compensator having negative optical dispersion comprising a polymerized compound according to claim 1 .

21. An optical, electronic or electrooptical component or device, comprising a compound according to claim 1 .

22. An optical component according to claim 21 , wherein said component is an optically uniaxial film selected from an A-plate, C-plate, negative C-plate or O-plate, a twisted optical retarder, a twisted quarter wave foil (QWF), an optically biaxial film, an achromatic retarder, an achromatic QWF or half wave foil (HWF), a film having a cholesteric, smectic, nematic or blue phase, a film having homeotropic, splayed, tilted, planar or blue-phase alignment, which is uniformly oriented or exhibits a pattern of different orientations.

23. An optical component according to claim 21 , wherein said component is an optical compensation film for viewing angle enhancement of LCD's, a component in a brightness enhancement films, or an achromatic element in reflective or transflective LCD's.

24. A device or component according to claim 21 , wherein said device or component is selected from electrooptical displays, LCDs, optical films, polarizers, compensators, beam splitters, reflective films, alignment layers, color filters, holographic elements, hot stamping foils, coloured images, decorative or security markings, LC pigments, adhesives, non-linear optic (NLO) devices, optical information storage devices, electronic devices, organic semiconductors, organic field effect transistors (OFET), integrated circuits (IC), thin film transistors (TFT), Radio Frequency Identification (RFID) tags, organic light emitting diodes (OLED), organic light emitting transistors (OLET), electroluminescent displays, organic photovoltaic (OPV) devices, organic solar cells (O-SC), organic laser diodes (O-laser), organic integrated circuits (O-IC), lighting devices, sensor devices, electrode materials, photoconductors, photodetectors, electrophotographic recording devices, capacitors, charge injection layers, Schottky diodes, planarising layers, antistatic films, conducting substrates, conducting patterns, photoconductors, electrophotographic applications, electrophotographic recording, organic memory devices, biosensors, biochips, optoelectronic devices requiring similar phase shift at multiple wavelengths, combined CD/DVD/HD-DVD/Blu-Rays, reading, writing re-writing data storage systems, and cameras.

25. A method for preparing a compound according to claim 1 , comprising:

a) reacting a suitably substituted acetylene with an optionally substituted cyclohexanone in the presence of butyllithium,

b) separating the isomers thereby formed,

c) reacting the hydroxy group of one isomer prepared according to a) and b) with a polymerizable group,

d) repeating a) and b) with the same or different cyclohexanone and acetylene educts,

e1) reacting one isomer prepared by d) with a dihaloalkane and butyllithium to yield a diether compound, or

e2) reacting one isomer prepared by d) with a diacid to yield a diester compound,

f) coupling the diester or diether prepared by e1) or e2), respectively, with a dihaloaromatic compound under Sonogashira conditions,

g) reacting the product of c) with the product of step f) under Sonogashira conditions.