Stock material or miscellaneous articles – Liquid crystal optical display having layer of specified...
Reexamination Certificate
2001-01-03
2004-07-06
Wu, Shean C. (Department: 1756)
Stock material or miscellaneous articles
Liquid crystal optical display having layer of specified...
C252S299610, C252S299630, C252S299640, C252S299650, C252S299660, C252S299670, C252S299620, C544S303000, C544S306000, C544S334000, C544S335000, C546S001000, C560S062000, C560S065000, C570S127000, C570S128000, C570S130000, C570S188000
Reexamination Certificate
active
06759101
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to compounds useful as components in liquid crystal (LC) compositions, particularly as components of LC compositions that exhibit smectic phases and more particularly as components of LC compositions that exhibit smectic A and/or smectic C phases. LC compositions of this invention may also exhibit nematic phases. LC compositions of this invention can be ferroelectric liquid crystals (FLCs). The invention also relates to optical devices employing LC compositions of the invention in optical switching and display elements.
Several types of smectic liquid crystal materials (LCs) have been investigated for rapid switching, view-angle enhancement and higher contrast, including surface-stabilized ferroelectric LCs (FLCs), deformed helix ferroelectric LCs (DHFLCs), and antiferroelectric LCs (AFLCs). Recently, smectic material exhibiting thresholdless or more properly V-shaped switching LCs (VSLCs) have been described (Inui, S. et al. (1996) J. Mater. Chem. 6(4):671-673; Seomun, S. S. et al. (1997) Jpn. J. Appl. Phys. 36:3580-3590). Ferroelectric LCs when aligned parallel to the substrate surfaces using the surface stabilized effect (in an surface-stabilized ferroelectric liquid crystal (SSFLC) device) exhibit two stable state switching on a microsecond time scale. Antiferroelectric LCs exhibit three stable-state switching, which by application of a bias field can be converted for use in a bistable switching mode LC devices. Two of the AFLC states have the same transmittance, so that alternate symmetrical switching can be used in AFLC devices. VLCs, in contrast, exhibit very rapid, analog electro-optic response, allow symmetrical driving, and no dc balance is required. VLCs are particularly attractive for applications requiring generation of multiple levels of gray scale.
Liquid crystal (LC) compositions exhibit one or more LC phases. LC compositions may be composed of one or more components. Components of LC compositions may exhibit liquid crystal phases, have latent liquid crystal phases or be compatible with (not suppress) liquid crystal phases in the LC composition. LC compounds and components of LC mixtures of this invention are rod-like molecules most typically having a generally linear mesogenic core with one or more directly or indirectly linked alicylic or aromatic rings (which may be fused aromatic rings) and two “floppy tail groups” (i.e., structurally flexible) that may be straight-chain or branched groups positioned on either side of the mesogenic core, e.g.:
The tails often have similar lengths, and both tails are typically longer than four carbons. LC components which do not themselves exhibit liquid crystal phases, but which exhibit LC phases on combination with one or more other components are described as having “latent” liquid crystal phases. Chiral nonracemic LCs useful in FLC, DHFLC, AFLC and VLC compositions have at least one component that has a chiral non-racemic tail group. FLC, DHFLC, AFLC and VLC compositions may be composed entirely of chiral non-racemic components, but are typically composed of a mixture of chiral nonracemic and achiral or racemic components.
SUMMARY OF THE INVENTION
LC compounds of this invention can be chiral nonracemic, chiral racemic or achiral. Compounds of this invention have a substantially linear liquid crystal core and two tails diposed substantially linearly with respect to each other on either side of the core. One tail contains a perfluoroalkyl terminal portion (the portion distal from the core) and the other tail contains a double bond which may be in the cis or trans configuration and which may be positioned internally (i.e., not at the &agr;- or &ohgr;-positions in the tail) or at the &agr;- or &ohgr;-positions in the tail with respect to the bond to the core. The perfluoroalkyl tail is achiral and the alkenyl tail can be chiral nonracemic, chiral racemic or achiral.
Compounds of this invention have the formula:
where:
a and b can be 0 or 1, indicating the presence or absence of the group within the brackets; Cores may have one (a=b=0) ring, two rings (a=0) or three rings (a=b=1);
A and B, independently, are linker groups selected from the group consisting of a single bond, —COO—, —OOC—. —CH
2
—CH
2
—, —OCH
2
—, —CH
2
—O—, —CH═CH— (cis or trans); —C≡C—, —CH═CH—CH═CH— (cis or trans);
Y indicates optional substitution on the core ring and can represent a plurality of substituents which may be the same or different on different ring positions, preferred core ring substituents are fluorine;
Core rings A, B and C can be aromatic or alicyclic and preferably are 6-membered rings, for aromatic rings one or two ring carbon as can be replaced with a heteroatom (a non-carbon atom), particularly N; alicyclic rings can contain 3-10 carbon atoms, preferably contain 5 or 6 carbons and may contain a double bond, one or two CH
2
of the alicyclic ring can be replaced with O or a C═O group, more preferred alicyclic rings are cyclohexane and cyclohexene rings; in specific embodiments one, two or three of the A, B and C rings are aromatic; in other embodiments one or two of the A, B or C rings are alicyclic;
m and n are integers ranging from 1 to 20, inclusive; p is an integer ranging from 2 to 20, inclusive; q is 0 or an integer ranging from 1 to 20; inclusive; n+m is 4 to 20 and p+q is 4 to 20;
X
1
and X
2
, independently, are —O— or a single bond; and
R and R′, independent of other R or R′ in the alkenyl tail are hydrogens, or alkyl groups, particularly lower alkyl groups having from 1 to 6 carbon atoms.
Compounds of this invention include compounds of the above formula having any one of the cores listed in Scheme 1.
In a specific embodiment, compounds of this invention have the formula:
where n, m, p, q, n+m, p+q, X
1
, X
2
, B, Ring B and Ring C can take values as noted above and each D, independent of other D's, can be CH or CH
2
, a nitrogen atom, CY or CHY, where Y is a CN, NO
2
, an alkyl, a perhaloalkyl (e.g., perfluoralkyl), or a halide, particularly a fluorine. Rings B and C can be alicyclic or aromatic and B and C that are aromatic can be fused ring systems, such as naphthalene. One of B or C can also be a fused ring system that is partially aromatic, such as a dehydronapthalene ring system. In particular embodiments, both of rings B and C are aromatic, or one of B and C is aromatic and the other of B or C is alicyclic, particularly a cyclohexane or cyclohexene ring. In preferred embodiments: (1) all D's are CH; (2) one or two D's are N and the remaining D's are CH; (3) one or two D's are CF and the remaining D's are CH; (4) one or two D's are N, one or two D's are CF and the remaining D's are CH; (3) all D's on one ring are CH
2
and one, two or three D's on the other ring can be N or CF; (4) all D's on one ring are CH
2
and all D's on the other ring are CH.
In a further specific embodiment, compounds of this invention have the formula:
where each D independent of other D's can be CH or CY as defined above or a nitrogen atom and all other variables are as defined above. In preferred compounds of Formula III, all D's are CH or one or two D's can be CF or nitrogen with the remaining D's being CH. In preferred embodiments, the core is a phenylpyrimidine, a phenylpyridine, phenylbenzoate, or biphenyl.
In another specific embodiment, compounds of this invention can have the formula:
where each D, independent of other D's, can be CH, CY or a nitrogen. In preferred compounds of Formula IV, all D's are CH or one or two D's can be CF or nitrogen with the remaining D's being CH.
In yet another specific embodiment, compounds of this invention can have the formula:
where variable have the values listed in Formula I above. In particular embodiments the core can be (1) an optionally substituted terphenyl, where the preferred substitution is one or two F's; (2) a core in which A or
Gough Neil
More Kundalika
Thurmes William N.
Vohra Rohini
Wand Michael
Displaytech, Inc.
Greenlee Winner and Sullivan P.C.
Wu Shean C.
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