Synergistic host-guest interactions in FLC mixtures for increased polarization and decreased switching speed
View Patent ↗The disclosed subject matter provides a chiral host-guest composition for a ferroelectric liquid crystal mixture, the host-guest composition comprising a chiral guest compound and an achiral host compound, wherein the host-guest composition induces a greater degree of polarization in the liquid crystal mixture than is induced in the mixture with a comparable amount of the chiral guest compound in the absence of the achiral host compound. The chiral guest is a fluorinated compound comprising a aryl or heteroaryl core substituted with an alkyl chain, wherein the alkyl chain includes one or more fluorine atoms, each fluorine atom being bonded to a chiral carbon atom. The achiral host possesses a central thiadiazole core, with at least one aryl/heteroaryl wing, further substituted with alkyl or alkoxy groups.
1. A chiral host-guest composition for a ferroelectric liquid crystal mixture, the host-guest composition comprising a chiral guest compound and an achiral host compound,
wherein the host-guest composition induces a greater degree of polarization in the liquid crystal mixture, per mass, than is induced in the mixture of the chiral guest compound in the absence of the achiral host compound, per mass,
wherein the weight percentage of the achiral host compound is 6% or more.
2. The host-guest composition of claim 1 wherein the guest is a compound comprising an aryl nucleus, the nucleus bearing an alkyl or alkoxy moiety substituted with at least one fluorine atom, wherein a position of fluorine substitution is a chiral center.
3. The host-guest composition of claim 2 wherein the alkyl moiety of the guest is substituted with two fluorine atoms, both positions of fluorine substitution being chiral centers.
4. The host-guest composition of claim 3 wherein both positions of fluorine substitution are of the same absolute configuration.
5. The host-guest composition of claim 1 wherein the guest compound is of formula (I)
R 1 —X 1 -AR-X 2 —R 2 ,
wherein R 1 is a linear (C 6 -C 18 )alkyl chain X 1 is 0 or is a bond, AR is one or two independently selected aryl or heteroaryl rings, X 2 is 0 or is a bond, and R 2 is a linear (C 6 -C 18 )alkyl chain substituted with one or two fluorine atoms, wherein each fluorine atom is bonded to a respective carbon atom such that a respective chiral center is present thereby.
6. The host-guest composition of claim 5 , wherein for the compound of formula (I) there are two chiral centers, each bearing a fluorine atom.
7. The host-guest composition of claim 1 wherein the enantiomeric purity of the chiral guest compound is at least about 80%, or more.
8. The host-guest composition of claim 5 wherein the guest compound is of formula (II)
wherein R 1 , X 1 , R 2 , and X 2 are as defined in claim 5 , and wherein ring A and ring B are each independently an aryl or heteroaryl ring.
9. The host-guest composition of claim 8 wherein for the guest compound one of ring A and ring B is phenyl and the other is a 2-pyridyl or a 3-pyridyl.
10. The host-guest composition of claim 5 wherein for the guest compound R 2 is a group of formula —(CH 2 ) m —CHF—CHF—(CH 2 ) n CH 3 wherein m is 1 to about 5 and n is 1 to about 10.
11. The host-guest composition of claim 1 wherein the guest compound is of formula
12. The host-guest composition of claim 1 wherein the host compound is a 2,5-disubstituted 1,3,4-thiadiazole or 1,3,4-oxadiazole.
13. The host-guest composition of claim 12 wherein the host compound is of formula (III-S)
or (III-0)
wherein Ar 1 and Ar 2 are independently (C 1 -C 12 )alkyl, (C 3 -C 8 )cycloalkyl, (C 3 -C 8 )cycloalkyl-(C 1 -C 12 )alkyl, para-(C 1 -C 12 )alkylaryl, para-(C 1 -C 12 )alkylheteroaryl, para-(C 1 -C 12 )alkoxyaryl, or para-(C 1 -C 12 )alkoxyheteroaryl groups, provided that only one of Ar 1 and Ar 2 is (C 1 -C 12 )alkyl.
14. The host-guest composition of claim 13 wherein for the host compound Ar 1 and Ar 2 are independently para-(C 4 -C 12 )alkylphenyl or para-(C 4 -C 12 )alkoxyphenyl.
15. The host-guest composition of claim 1 wherein the host compound is
16. A ferroelectric liquid crystal mixture comprising the host-guest composition of claim 1 .
17. A ferroelectric liquid crystal display comprising the host-guest composition of claim 1 .
18. An electronic display device comprising the host-guest composition of claim 1 , or the liquid crystal display of claim 17 .
19. The display device of claim 18 wherein the device is comprised by a cell phone, a smart phone, a tablet, or a computer display screen.
20. The chiral host-guest composition of claim 2 , wherein the weight percentage of the achiral host compound is 10% or more.
21. The chiral host-guest composition of claim 20 , wherein the weight percentage of the chiral guest compound is 10% or more.
22. A chiral host-guest composition for a ferroelectric liquid crystal mixture, the host-guest composition comprising a chiral guest compound and an achiral host compound,
wherein the weight percentage of the achiral host compound is 10% or more,
wherein the chiral guest compound is a formula,
wherein the achiral host compound is a 2,5-disubstituted 1,3,4-thiadiasole or 1,3,4-oxadiazole.
23. A chiral host-guest composition for a ferroelectric liquid crystal mixture, the host-guest composition comprising a chiral guest compound and an achiral host compound,
wherein the weight percentage of the achiral host compound is 10% or more,
wherein the chiral guest compound is a formula,
wherein the achiral host compound is