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WO 2006/075882 PCT/KR2006/000131
Description
LIQUID CRYSTAL COMPOSITION COMPRISING NOVEL
SILICON CONTAINING COMPOUNDS AND LIQUID CRYSTAL
DISPLAY DEVICE USING THE SAME
Technical Field
[ 1 ] The present invention relates to a novel silicon-containing compound and a liquid
crystal composition comprising the same. More particularly, the present invention
relates to a novel nematic liquid crystal compound, which has low viscosity and high
negative dielectric anisotropy, a liquid crystal composition comprising the same
compound, and a liquid crystal display device using the same composition.
Background Art
[2] In general, liquid crystal compounds having optical anisotropy (An) and dielectric
anisotropy (Af.) are widely used in display devices such as clocks, notebook PCs,
mobile phones, televisions and monitors. Such liquid crystal compounds are in-
creasingly in demand. Liquid crystal compounds used in such display devices include a
nematic liquid crystal phase, a smectic liquid crystal phase and a cholesteric liquid
crystal phase. Among those phases, nematic phases are the most widely used. In
practice, various liquid crystal compounds are used in the form of a composition.
Liquid crystal compositions should be stable against water, light, heat, air, electric
fields or the like, and have to ensure the chemical stability among the compounds
forming the composition under the conditions of particular use. In order to use a liquid
crystal compound in a display device, the liquid crystal compound should be in
harmony of physical properties, including a wide range of liquid crystal phase tem-
peratures, optical anisotropy value (An) and dielectric anisotropy value (Ae), viscosity
and conductivity. Properties of a liquid crystal compound required for a display device
depend on the specific type of the display device. Therefore, there is an imminent need
for a novel liquid crystal device that satisfies the above properties at the same time.
Recently, there has been a need for a liquid crystal display device having a fast
response time in order to treat a great amount of information promptly.
Disclosure of Invention
Technical Problem
[3] Therefore, the present invention has been made in view of the above-mentioned
problems. It is an object of the present invention to provide a novel liquid crystal
compound, which has low viscosity as well as high negative dielectric anisotropy so as
to permit optimization of display. It is another object of the present invention to

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provide a liquid crystal composition comprising the above compound. It is still another
object of the present invention to provide a liquid crystal display device manufactured
by using the above composition.
Technical Solution
[4] The present invention provides a novel silicon-containing compound represented by
the following formula 1, a liquid crystal composition comprising the above compound,
and a liquid crystal display device comprising a liquid crystal layer prepared from the
above liquid crystal composition:
[5] [Formula 1]
[6]


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[11] wherein the substituents, which are introduced into ring B, ring C or ring D and
represented by L to L , are independent from each other, even if they have the same
designations;
[12] M is selected from C, N and Si, with the proviso that if M is N, L or L is null;
[13] Z is C;
[14] each of a , a and a is independently selected from C, NR and O;
[15] E is selected from the group consisting of SiMe2 Ok2(CQ2)n2, SiEt2Ok2(CQ2)n2, SiF2O
k2(CQ2)n2, SiCl2Ok2(CQ2)n2, SiMe2 (CQ2)n2Ok2, SiEt2 (CQ2)n2Ok2, SiF2(CQ2)n2On2,SiCl2(CQ
2)n2Ok2,Ok2SiMe2(CQ2)n2,Ok2SiEt2(CQ2)n2,Ok2SiF2(CQ2)n2,Ok2 SiCl2(CQ2)n2,(CQ2)n2Ok2
SiMe2, (CQ2)n2Ok2SiEt2, (CQ2)n2Ok2SiF2;(CQ2)n2Ok2SiCl2, Ok2(CQ2)n2SiMe2,Ok2(CQ2)n2
SiEt2,Ok2(CQ2)n2SiF2,Ok2(CQ2)n2SiCl2, (CQ2)n2SiMe2Ok2,(CQ2)n2SiEt2Ok2,(CQ2)n2SiF2
Ok2,(CQ2)n2SiCl2Ok2,(CH2)n2,C=C,O,S,COO,OCO,CF2O,OCF2,OCOO,CH2O,
CH2CO, OCH2 and COCH2, wherein k2 is 0 or 1, Q is H or F, and n2 is an integer
between 0 and 3;
[16] R is selected from the group consisting of H, a C1 ~C15 alkyl group, a C2 ~C15 alkene
group and an alkoxy group (R1O), wherein the alkene group is CH=CH2 , CH=CHCH3
(E,Z), CH2CH=CH2, CH=CHCH2CH3 (E,Z), CH2CH=CHCH3 (E,Z), CH2CH2CH=CH2,
CH=CHCH2CH2CH3(E,Z), CH2CH=CHCH2CH3(E,Z), CH2CH2CH=CHCH3 (E,Z) or
CH2CH2CH2CH=CH2;
[17] R is selected from the group consisting of H, a C ~C alkyl group and a C ~C
alkene group, wherein the alkene group is CH=CH , CH=CHCH (E,Z), CH CH=CH,
CH=CHCH2CH3 (E,Z), CH2CH=CHCH3 (E,Z), CH2CH2CH=CH2, CH=CHCH2CH2CH
(E,Z), CH CH=CHCH CH (E,Z), CH CH CH=CHCH (E,Z) or CH CH CH CH=CH
2'
[18] X is selected from the group consisting of H, SiR R R , CF , OCF , CN, NCS,
halogen atoms and R;
[19] each of R , R and R is independently selected from R and halogen atoms;
[20] each ofL,L,L,L,L,L and L is independently selected from the group
consisting of H, halogen atoms, CN, CF, OCF and NCS;
[21] each of o, p and q independently represents an integer between 0 and 2; and
[22] at least one of E, A and X contains silicon.
[23] Hereinafter, the present invention will be explained in more detail.

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[24] The present invention provides a novel silicon-containing compound that may be
applied in various display devices, a liquid crystal composition essentially comprising
the silicon-containing compound, preferably a negative nematic liquid crystal
composition, and a liquid crystal display device using the above liquid crystal
composition. The silicon-containing compound is characterized by having low
viscosity, and high negative (-) dielectric anisotropy.
[25] High dielectric anisotropy is required for the operation of a liquid crystal under a
low driving voltage. According to the present invention, the liquid crystal compound
has dissymmetry of substituents based on the major axis of the molecule, thereby
providing high negative dielectric anisotropy.
[26] Low viscosity is required to obtain a fast response time of a liquid crystal.
According to the compound of the present invention, it is possible to obtain low
viscosity by introducing a silicon-containing substituent into at least one of the linking
groups (A and E) and terminal group (X), or both of the linking groups and terminal
group.
[27] Further, according to the present invention, it is possible to improve dipole moment
by introducing a halogen atom and/or alkyl group as a substituent for the hydrogen
atom, which forms a primary bond with silicon when a silicon-containing substituent is
introduced into at least one of the linking groups and/or terminal group. Such improved
dipole moment results in improvement in the dielectric anisotropy, which is affected
significantly by the polarizability and dipole moment.
[28] Preferred embodiments of the silicon-containing compound represented by formula
1 according to the present invention, which comprise preferred examples of ring B and
ring C, are represented by the following formulae 2~10. However, the scope of the
present invention is not limited thereto.
[29] [Formula 2]
[30]


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[471 wherein Z is C;
[48] M is C, Nor Si, with the proviso that if Mis N,L orL is null;
[49] each of a, a and a is independently selected from C, NR and O;
[50] each of L,L,L,L,L,L and L is independently selected from the group
consisting of H, halogen atoms, CN, CF, OCF and NCS; and
[51] A, E, R, X, o, p and q are the same as defined in formula 1.
[52] Particular preferred examples of the compounds represented by formulae 2~10
include the following compounds. However, the scope of the present invention is not
limited thereto.

[53]

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[62] wherein A is selected from the group consisting of SiO (CQ) , Si(CO ) O , (CQ
) O Si,(CQ) SiO ,O (CQ) SiandO Si(CQ) , andk , Q^I^R,R,R ,L ,L
, L , L , L , L, X, M, a , a and a are the same as defined in formula 1.
[63] Stereoisomers of the silicon-containing compound represented by formula 1 are
also included in the scope of the present invention. Herein, the silicon-containing
compound having stereoisomers is present preferably in the trans-form with liquid
crystal characteristics. Additionally, stereoisomers of the silicon-containing compound
may be present in the ratio of trans-isornercis-isomer of 85~100:15~0, but are not limi
ted thereto.

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[64] The novel silicon-containing compound represented by formula 1 is chemically and
thermally stable, is stable to light, and can form a mesomorphic phase (meso-phase) at
a desired temperature range so as to be used suitably for display applications.
[65] The silicon-containing compound represented by formula 1 according to the present
invention may be prepared by a method generally known to one skilled in the art.
According to a preferred embodiment of the present invention, the silicon-containing
compound represented by formula 1 may be prepared by way of the following
Reaction Schemes 1~6.
[66] [Reaction Scheme 1]
[67]

[68] In one embodiment of the method represented by Reaction Scheme 1,
4-n-propylcyclohexanone is subjected to the Grignard reaction, followed by de-
hydration using TsOH. The resultant product is allowed to react with n-BuLi to form
an anion, which in turn is allowed to react with a silyl chloride derivative. Next, hy-
drogenation is performed by using the Raney-Nickel catalyst in order to form a trans
isomer, thereby providing a silyl liquid crystal compound represented by formula 11,
in which ring B or ring C is 1,4-cyclohexyl. Otherwise, the trans isomer may be
formed by way of hydrogenation using Pd/charcoal and recrystallization.
[69] [Reaction Scheme 2]
[70]


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[71] In one embodiment of the method represented by Reaction Scheme 2,
4-n-propylcyclohexanone is subjected to the Grignard reaction, followed by de-
hydration using TsOH. Then, the resultant product is converted into an anionic form by
using n-BuLi, and then is allowed to react with the silyl chloride derivative. If the
reaction with p-chloranil is used instead of hydrogenation, the silyl liquid crystal
compound represented by formula 12, in which ring B or ring C is 1,4-phenyl, can be
obtained.
[72] [Reaction Scheme 3]
[73]

[74] In one embodiment of the method represented by Reaction Scheme 3,
4-n-propylcyclohexanone is subjected to the Grignard reaction, followed by de-
hydration using TsOH. Next, the resultant product is converted into its anionic form by
using n-BuLi, and then is allowed to react with the silyl chloride derivative. If the
reaction with p-chloranil is used instead of hydrogenation, the silyl liquid crystal
compound represented by formula 13, in which ring B or ring C is 1,4-phenyl, can be
obtained.
[75] [Reaction Scheme 4]
[76]

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[77] In one embodiment of the method represented by Reaction Scheme 4, Pd-coupling
reaction is performed by using a boronic acid derivative to provide a biphenyl or
triphenyl derivative, which, in turn, is converted into an anion by using n-BuLi. Then,
the resultant product is allowed to react with the silyl chloride to provide the silyl
liquid crystal compound represented by formula 14.
[78] [Reaction Scheme 5]
[79]

[80] In one embodiment of the method represented by Reaction Scheme 5, Pd-coupling
reaction is performed by using a boronic acid derivative to provide a biphenyl or
triphenyl derivative, which, in turn, is converted into an anion by using n-BuLi. Then,
the resultant product is allowed to react with the silyl chloride to provide the silyl
liquid crystal compound represented by formula 15.
[81] [Reaction Scheme 6]
[82]

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[83] In one embodiment of the method represented by Reaction Scheme 6, an excessive
amount of Me SiCl is added to the anion formed by Mg to provide the silyl chloride
derivative, which, in turn, is allowed to react with a phenyl magnesium derivative to
provide the silyl liquid crystal compound represented by formula 16.
[84] In addition to the compounds obtained by way of the above Reaction Schemes 1 ~6,
compounds obtained by similar methods or conventional methods known to one skilled
in the art are also included in the scope of the present invention. The silicon-containing
compounds obtained as described above may be mixed in an adequate ratio to provide
a liquid crystal composition.
[85] The present invention provides a liquid crystal composition, preferably a nematic
liquid crystal composition, which comprises the silicon-containing compound
represented by formula 1.
[86] To provide the desired liquid crystal characteristics by a liquid crystal composition,
about 5~20 components are generally used in combination in the liquid crystal
composition. According to the present invention, it is possible to provide a liquid
crystal composition having a low driving voltage and a fast response time by using the
novel silicon-containing compound represented by formula 1, which can serve to
impart high negative dielectric anisotropy as well as to reduce viscosity.
[87] Although there is no particular limitation in the content of the compound
represented by formula 1, more particularly at least one compound selected from the
group consisting of the silicon-containing liquid crystal compounds represented by
formulae 2~10, each compound is preferably used in an amount of l~50 wt% based on
100 wt% of the total liquid crystal composition.
[88] The liquid crystal composition according to the present invention may further
comprise other liquid crystal compounds, currently used in a conventional liquid
crystal composition, in addition to the silicon-containing compound represented by
formula 1. Such compounds may be used in a controlled ratio, as necessary. Ad-
ditionally, suitable additives may also be used, and such additives are disclosed in [H.
Kelker/R. Hatz, Handbook of Liquid Crystals, Verlag Chemie, Weinheim, 1980]. For
example, additives for modifying the dielectric anisotropy, viscosity and/or alignment
of a nematic phase may be used. Particular examples of the additives that may be used
in the liquid crystal composition according to the present invention include chiral

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dopants that inhibit the helical structure and reverse distortion of a liquid crystal,
dichroic dyes, or the like.
[89] The liquid crystal composition according to the present invention may be prepared
by a method generally known to one skilled in the art. In one embodiment of such
methods, various components that form the liquid crystal composition are dissolved at
a temperature ranging from room temperature to a high temperature.
[90] Also, the present invention provides a Equid display device, which comprises a
liquid crystal layer obtained from the liquid crystal composition.
[91 ] There is no particular limitation in the liquid crystal display device. Particular
examples of the liquid crystal display device include display devices that require
negative dielectric anisotropy, such as a vertical alignment liquid crystal display
device, a patterned vertical alignment liquid crystal display device, superpatterned
vertical alignment liquid crystal device, or the like.
[92] The liquid crystal display device according to the present invention may be man-
ufactured by a method generally knpwn to one skilled in the art. One embodiment of
such methods, a liquid crystal composition is dissolved at a suitable temperature, and
then introduced into a liquid crystal device. The liquid crystal phase, dissolved as
mentioned above, may be modified so that it can be applied for all types of liquid
crystal display devices by virtue of the use of suitable additives.
Mode for the Invention
[93] Reference will now be made in detail to the preferred embodiments of the present
invention. It is to be understood that the following examples are illustrative only and
the present invention is not limited thereto.
[94] [Examples 1-17]
[95] Example 1
[96]

[97] First, 500 mg of Mg was dissolved into dry THF, and a solution containing 5.6 g of
4-bromo-4'-n-propylbiphenyl dissolved in 20 ml of dry THF was added gradually
thereto to form a Grignard reagent. Next, 5.3 g of dichlorodimethylsilane was added
thereto at 0°C, and the reaction mixture was allowed to react for about 3 hours. An
excessive amount of hexane was added thereto, so that magnesium precipitate was
formed. The precipitate was removed via filtration. After the analysis of the reaction
product by NMR spectrometry, it was shown that mono-coupling compound and di-
coupling compound was present in the ratio of about 90:10 (mono:di). When at least 2

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equivalents of the silane compound are used at low temperature, it is possible to reduce
the production of di-coupling compound to a ratio of 10% or less. In this case, it is
possible to cany out subsequent steps with no separation of di-coupling compound.
Then, a Grignard reagent was formed by using 2.1g of l-bromo-2,3,4-trifluorobenzene
and 240 mg of Mg in 20 ml of dry THF. To the reagent, 3.4 g of the crude mono-
coupling compound was added and the reaction mixture was heated to 60°C. After
stirring for about 10 hours, the reaction mixture was worked up with water and hexane,
and then purified by silica gel column chromatography to obtain the silicon-containing
compound represented by the above formula (yield: 87%). 400MHz ^-NMR, CDC1,
5(ppm) : 0.61 (s, 6H), 0.98 (t, 3H), 1.66-1.69 (m, 2H), 2.65 (t, 2H), 7.05 (m, 1H), 7.24
(d, 2H), 7.49 (m, 1H), 7.55-7.62 (m, 6H).
[98] Example 2
[99]

[100] First, 1.0 equivalent of l-bromo-3,4-difluorobenzene was dissolved into dry THF,
and 1.1 equivalents of Mg were added thereto to form a Grignard reagent, which, in
turn, was allowed to react with 2.0 equivalents of dichlorodimethylsilane. Next,
chlorodimethyl(3,4-difluorophenyl)silane was obtained via vacuum distillation. Then,
255 mg of Mg was dissolved into 10 ml of dry THF, and a solution containing 2.80 g
of 4-bromo-4'-n-propylbiphenyl dissolved in dry THF was added thereto to form a
Grignard reagent To the Grignard reagent, 2.17 g of the
chlorodimethyl(3,4-difluorophenyl)silane obtained as described above was added at
room temperature. After stirring for about 10 hours, the reaction mixture was worked
up with water and hexane, and then purified by silica gel column chromatography to
obtain the silicon-containing compound represented by the above formula (yield:
85%). 400MHz 'H-NMR, CDC1,6(ppm): 0.60 (s, 6H), 1.00 (t, 3H), 1.68-1.74 (m,
2H), 2.66 (t, 2H), 7.16-7.19 (m, 1H), 7.21-7.33 (m, 4H), 7.53-7.63 (m, 6H).
[101] Example 3
[102]

[103] First, 1.0 equivalent of l-bromo-4-fluorobenzene was dissolved into dry THF, and
1.1 equivalents of Mg were added thereto to form a Grignard reagent, which, in turn,
was allowed to react with 2.0 equivalents of dichlorodimethylsilane. Next,
chlorodimethyl(3,4-difluorophenyl)silane was obtained via vacuum distillation. Then,

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3.24 g of 2,3-difluoro-4'-n-propylbiphenyl was dissolved into 20 ml of dry THF under
nitrogen atmosphere, 7.3 ml of 2.0M n-Buli was added to the solution at -78°C, and
the reaction mixture was stirred sufficiently for about 3 hours to form an anion. To the
anion, 2.64g of the chlorodimethyl(4-fluorophenyl)silane obtained as described above
was added, the reaction mixture was warmed to room temperature, and then was stirred
for about 1 hour. Then, the reaction mixture was worked up with water and hexane,
and purified by silica gel column chromatography to obtain the silicon-containing
compound represented by the above formula (yield: 91%). 400MHz 1H-NMR, CDC13,
6(ppm): 0.66 (s, 6H), 1.02 (t, 3H), 1.68-1.71 (m, 2H), 2.66 (t, 2H), 7.04-7.09 (m,
1H), 7.15 (dd, 2H), 7.19-7.23 (m, 1H), 7.29 (d, 2H), 7.48 (d, 2H), 7.61 (dd, 2H).
[104] Example 4
[105]

[106] First, 6.40 g of 2,3-difiuoro-4'-n-propylbiphenyl was dissolved into 30 ml of dry
THF under nitrogen atmosphere, and 14.0 mL of 2.0M n-BuLi was added thereto at -
78°C. Then the reaction mixture was stirred sufficiently for about 3 hours to form an
anion. To the anion, 5.77g of the chlorodimethy1(3,4-difluorophenyl)- silane obtained
as described in Example 2 was added, the reaction mixture was warmed to room
temperature and stirred for about 1 hour at room temperature. Then, the reaction
mixture was worked up with water and hexane. Finally, the reaction product was
purified by silica gel column chromatography to obtain the silicon-containing
compound represented by the above formula (yield: 88%). 400MHz !H-NMR, CDC1,
8(ppm) : 0.63 (s, 6H), 1.05 (t, 3H), 1.71-1.86 (m, 2H), 2.77 (t, 2H), 7.12-7.21 (m,
1H), 7.29-7.35 (m, 2H), 7.38-7.49 (m, 3H), 7.55 (t, 1H), 7.62 (d, 2H).
[107] Example 5
[108]

[109] First, 1.20 g of 1,2-difluorobenzene was dissolved into 20 ml of dry THF under
nitrogen atmosphere, 4.0 mL of 2.5M n-BuLi was added thereto at -78°C, and the
reaction mixture was stirred for about 3 hours to form an anion. Next, 2.0 g of trans-
cyclohexane was added thereto at low temperature, the reaction mixture was warmed
to room temperature, and was stirred for about 2 hours at room temperature. Then, the
reaction mixture was worked up with water and ether, and subjected to evaporation

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under reduced pressure to obtain a tertiary alcohol compound. The tertiary alcohol
compound was dissolved into CH Cl solvent, 500 mg of p-toluenesulfonic acid was
added thereto, and the reaction mixture was stirred at 60°C for 10 hours to carry out de-
hydration reaction. After cooling to room temperature, the reaction mixture was
worked up with water and CH Cl, and was purified by silica gel column chro-
matography to obtain the cyclohexene compound with a yield of about 80%. Then, 2g
of the compound was dissolved into 10 ml of dry THF, 2.80 ml of 2.5M n-BuLi was
added thereto at -78°C, and the reaction mixture was stirred for about 3 hours to form
an anion. To the anion, 1.0 g of trimethylsilyl chloride was added at low temperature
and was warmed gradually to room temperature. After stirring at room temperature for
about 1 hour, the reaction mixture was worked up with water and hexane and purified
by silica gel column chromatography to obtain the silicon-containing compound
represented by the above formula (yield: 95%). 400MHz 'H-NMR, CDC1, 6(ppm):
0.33 (s, 9H), 0.91 (t, 3H), 0.93-1.11 (m, 4H), 1.12-1.24 (m, 3H), 1.24-1.53 (m, 6H),
1.72~1.88 (m,3H), 1.88~2.05 (m,2H),2.21~2.29 (br,1H), 2.29~ (m,2H), 5.98
(br, 1H), 6.95-7.04 (m, 2H).
[110] Example 6
[111]

[112] First, 2g of the cyclohexene compound obtained from Example 5 was dissolved in
10 ml of xylene, 3.5 g of p-chloranil was added thereto, and the reaction mixture was
heated at 150°C for about 10 hours to perform a reaction. After cooling the reaction
mixture to room temperature, hexane was added until the precipitate was formed.
Then, the precipitate was filtered by using celite/silica gel. Finally, the reaction
mixture was purified by silica gel column chromatography to obtain the silicon-
containing compound represented by the above formula (yield: 83%). 400MHz H-
NMR, CDC1, 5(ppm) : 0.38 (s, 9H), 0.92 (t, 3H), 1.07-1.15 (m, 2H), 1.20-1.28 (m,
2H), 1.30-1.45 (m, 3H), 1.45-1.58 (m, 2H), 1.87-1.99 (br, 4H), 2.53 (t, 1H),
7.11-7.19 (m, 2H), 7.29 (d, 2H), 7.49 (d, 2H).
[113] Example 7
[114]

[115] First, 3.0 g of 4-bromo-4'-n-propylbiphenyl was dissolved into 27 ml of DME, and
2.0 g of 2,3-difluorophenylboronic acid, 380 mg of tetrakis(triphenyl

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phosphine)palladium (0) and 27 ml of 2.0M Na CO was added thereto. Next, the
reaction mixture was heated to 100°C to perform a reaction for about 10 hours. After
checking complete disappearance of 4-bromo-4'-n-propylbiphenyl on TLC, the
reaction mixture was cooled to room temperature, worked up with water and ether, and
then purified by silica gel column chromatography to obtain the triphenyl compound
with a yield of 90%. Then, 2.8 g of the triphenyl compound was dissolved into 10 ml
of dry THF under nitrogen atmosphere, 4.3 ml of 2.5M n-BuLi was added thereto at -
78°C to form an anion over about 3 hours. Then 1.5 ml of TMSC1 was added thereto,
and the reaction mixture was warmed gradually to room temperature. After stirring at
room temperature for about 1 hour, the reaction mixture was worked up with water and
hexane, and then purified by silica gel column chromatography to obtain the silicon-
containing compound represented by the above formula (yield: 96%). 400MHz3 H-
NMR, CDC13,o(ppm) : 0.39 (s, 9H), 1.04 (t, 3H), 1.66-1.76 (m, 2H), 2.66 (t, 2H),
7.18-7.21 (m, 1H), 7.21-7.28 (m, 1H), 7.31 (d, 2H), 7.58 (d, 2H), 7.64 (d, 2H), 7.70
(d,2H).
[116] Example 8
[117]

[118] First, 4.8 g of 4-bromo-4'-n-pentylbiphenyl was added to 40 ml of DME, and 3.0 g
of 2,3-difluorophenylboronic acid, 550 mg of tetrakis(triphenylphosphine)palladium(0)
and 40 ml of 2.0M Na CO was added thereto. Next, the reaction mixture was allowed
to react for about 10 hours, while heating the reaction mixture at 100°C. The reaction
mixture was cooled to room temperature and worked up with water and ether, and then
purified by silica gel column chromatography to obtain the triphenyl compound with a
yield of 88%. Then, 4.0 g of the triphenyl compound was dissolved into 20 ml of dry
THF under nitrogen atmosphere, and 5.7 ml of 2.5M n-BuIi was added thereto to form
an anion over about 3 hours. Then 2.0 ml of TMSC1 was added thereto, and the react
ion mixture was warmed gradually to room temperature. After stirring at room
temperature for about 1 hour, the reaction mixture was worked up with water and
hexane, and then purified by silica gel column chromatography to obtain the silicon-
containing compound represented by the above formula (yield: 95%). 400MHz] H-
NMR, CDC13,6(ppm) : 0.38 (s, 9H), 0.95 (m, 3H), 1.35-1.43 (m, 4H), 1.62-1.73 (m,
2H), 2.67 (t, 2H), 7.18-7.20 (m, 1H), 7.20-7.26 (m, 1H), 7.29 (d, 2H), 7.57 (d, 2H),
7.62 (d, 2H), 7.68 (d, 2H).
[119] Example 9

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[120]

[121] First, 7.9 g of l-bromo-4-trimethylsilylbenzene was dissolved into 86 ml of DME,
and 6.5 g of 2,3-difluorophenylboronic acid, 1.2 g of
tetrakis(triphenylphosphine)palladiuin (0) and 86 ml of 2.0M Na CO was added
thereto. Next, the reaction mixture was heated to 100°C to perform a reaction for about
10 hours. After being cooled to room temperature, the reaction mixture was worked up
with water and ether, and then purified by silica gel column chromatography to obtain
the 4/-trimethylsilyl-2,3-difluorobiphenyl compound with a yield of 91%. Then, 3.0 g
of the biphenyl compound was dissolved into 20 ml of dry THF under nitrogen
atmosphere, and 5.0 ml of 2.5M n-BuLi was added thereto at -78°C to form an anion
over about 3 hours. Then, 2.0 ml of 4-n-propylcyclohexanone was added to the anion,
and the reaction mixture was warmed^radually to room temperature. After stirring at
room temperature for 2 hours, the reaction mixture was worked up with water and
ether, and evaporated under reduced pressure, and then dissolved into CH Cl solvent.
Next, 1.0 g of TsOH was added thereto, and the reaction mixture was allowed to react
at 60°C for 10 hours. After the completion of the reaction, the reaction mixture was
purified by silica gel column chromatography to obtain the silicon-containing
compound (yield: 80%). 400MHz 'H-NMR, CDC13, 8(ppm): 0.38 (s, 9H), 0.97 (m,
3H), 1.34-1.46 (m, 5H), 1.63-1.76 (br, 1H), 1.84-1.98 (m, 2H), 2.33-2.59 (m, 3H),
6.06 (br, 1H), 7.05-7.12 (m, 1H), 7.12-7.18 (m, 1H), 7.56 (d, 2H), 7.63 (d, 2H).
[122] Example 10
[1231

[124] First, 2.5 g of the cyclohexene compound obtained from Example 9 was dissolved
in 10 ml of xylene, 4.0 g of p-chloranil was added thereto, and the reaction mixture
was heated at 150°C for about 10 hours to perform a reaction. After cooling the
reaction mixture to room temperature, hexane was added until the precipitate was
formed. Then, the precipitate was filtered by using celite/silica gel. Finally, the
reaction mixture was purified by silica gel column chromatography to obtain the
silicon-containing compound represented by the above formula (yield: 85%). 400MHz
'H-NMR, CDC13, 5(ppm) : 0.36 (s, 9H), 1.02 (t, 3H), 1.69-1.78 (m, 2H), 2.69 (t, 2H),
7.21-7.28 (m, 2H), 7.30 (d, 2H), 7.54 (d, 2H), 7.63 (d, 2H), 7.68 (d, 2H).

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[125] Example 11
[126]

[127] First, 3.48 g of 4'-trimethylsilyl-2,3-difluorobiphenyl was dissolved into 20 ml of
dry THF, and 5.8 ml of 2.5M n-BuLi was added thereto at -78°C to form an anion over
about 3 hours. Next, 2.8 ml of 4-n-pentylcyclohexanone was added thereto and the
reaction mixture was wanned gradually to room temperature. The reaction mixture was
stirred at room temperature for about 2 hours, worked up with water and ether, and
evaporated under reduced pressure. Then, the reaction mixture was dissolved into CH
Cl solvent, 1.0 g of TsOH was added thereto, and the reaction mixture was allowed to
react at 60°C for about 10 hours. After the completion of the reaction, the reaction
mixture was purified by silica gel column chromatography to obtain the silicon-
containing compound represented by the above formula (yield: 82%). 400MHz] H-
NMR, CDC1, 5(ppm) : 0.33 (s, 9H), 0.93 (m, 3H), 1.29-1.53 (m, 9H), 1.60-1.71 (br,
1H), 1.81-1.97 (m, 2H), 2.34-2.50 (m, 3H), 6.04 (br, 1H), 7.03-7.102 (m, 1H),
7.10-7.16 (m, 1H), 7.55 (d, 2H), 7.62 (d, 2H).
[128] Example 12
[129]

[130] First, 2.3 g of the cyclohexene compound obtained from Example 9 was dissolved
in 10 ml of xylene, 4.1 g of p-chloranil was added thereto, and the reaction mixture
was heated at 150°C for about 10 hours to perform a reaction. After cooling the
reaction mixture to room temperature, hexane was added until the precipitate was
formed. Then, the precipitate was filtered by using celite/siiica gel. Finally, the
reaction mixture was purified by silica gel column chromatography to obtain the
silicon-containing compound represented by the above formula (yield: 83%). 400MHz
'H-NMR, CDC1, 8(ppm) : 0.33 (s, 9H), 0.92-0.95 (m, 3H), 1.36-1.41 (m, 4H),
1.65-1.74 (m, 2H), 2.68 (t, 2H), 7.24-7.27 (m, 2H), 7.30 (d, 2H), 7.52 (d, 2H), 7.59 (d,
2H), 7.64 (d, 2H).
[131] Example 13
[132]

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[133] First, 7.28 g of 2,3-difluoro-4-iodo-4'-n-pentylbiphenyl was dissolved into 50 nil of
DME as a solvent. Next, 3.85 g of 2,3-difluorophenylboronic acid, 705 mg of
tetrakis(triphenylphosphine)palladium(0) and 50 ml of 2.OM Na CO was added
thereto, and the reaction mixture was heated at 100°C for about 10 houis. After being
cooled to room temperature, the reaction mixture was worked up with water and
hexane, and purified by silica gel column chromatography to obtain the triphenyl
compound with a yield of 70%. Then, 2.2 g of the triphenyl compound was dissolved
into 10 ml of dry THF under nitrogen atmosphere, and 3.1 ml of 2.5M n-BuLi was
added at -78°C to form an anion over about 3 hours. Then, 1.0 ml of TMSC1 was added
thereto and the reaction mixture was wanned gradually to room temperature. After
being stirred at room temperature for about 1 hour, the reaction mixture was worked up
with water and hexane, and then purified by silica gel column chromatography to
obtain the silicon-containing compound represented by the above formula (yield:
90%). 400MHz 'H-NMR, CDC13, 5(ppm): 0.39 (s, 9H), 1.00 (m, 3H), 1.67-1.74 (m,
2H), 2.67 (t, 2H), 7.16-7.22 (m, 2H), 7.27-7.32 (m, 4H), 7.52 (d, 2H).
[134] Example 14. Liquid Crystal Composition (1)
[135] A liquid crystal composition was prepared from the materials as shown in the
following Table 1. In Table 1, each percent ratio refers to parts by weight per hundred
parts of composition.
[136] [Table 1]
[137]

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[138] Example 15. Liquid Crystal Composition (2)
[139] A liquid crystal composition was prepared from the materials as shown in the
following Table 2. In Table 2, each percent ratio refers to parts by weight per hundred
parts of composition.
[140] [Table 2]
[141]

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[142] Example 16. Liquid Crystal Composition (3)
[143] A liquid crystal composition was prepared from the materials as shown in the
following Table 3. In Table 3, each percent ratio refers to parts by weight per hundred
parts of composition.
[144] [Table 3]
[145]

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[146] Experimental Example 1. Evaluation for Physical Properties of Liquid Crystal
Composition
[ 147] The liquid crystal compositions according to the present invention were evaluated
for their physical properties according to the following test.
[148] The liquid crystal compositions according to Examples 14~16 were used. Each
composition was introduced into a test tube in an amount of 1 g under the nitrogen
atmosphere, and then heated at 150°C for 2 hours to measure the phase transition
temperature. Herein, clearing point (c.p.) of each composition refers to the isotropic
liquid phase transition temperature in a nematic phase. Additionally, optical anisotropy
(An) of each composition was measured at 20°C/589 nm, while dielectric anisotropy
(Ae) of each composition was measured at 20°C/l kHz. Also, rotational viscosity (y )
of each composition was measured at 20°C. The results are shown in the following
Table 4.

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[149] After the test, it can be seen that the liquid crystal compositions according to
Examples 14~16, which comprise, as an active component, the novel silicon-
containing compound represented by formula 1 according to the present invention,
show high negative (-) dielectric anisotropy and low viscosity (see Table 4).
[150] [Table 4]
[151]

Ex. Clearing Optical Dielectric Viscosity
point (*C ) anisotropy anisotropy [mPas)
14 98 0.127 -5.9 112
IS 91 0.116 -5.7 94
16 102 0.099 -5.8 105
Industrial Applicability
[152] As can be seen from the foregoing, the present invention provides a novel nematic
liquid crystal compound, which has low viscosity and high negative dielectric
anisotropy, and a liquid crystal composition comprising the same compound.
According to the present invention, it is possible to provide a liquid crystal display
device that satisfies various desired characteristics, including a fast response time and a
low driving voltage.
[153] While this invention has been described in connection with what is presently
considered to be the most practical and preferred embodiment, it is to be understood
that the invention is not limited to the disclosed embodiment and the drawings. On the
contrary, it is intended to cover various modifications and variations within the spirit
and scope of the appended claims.

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Claims
[1] A silicon-containing compound represented by the following formula 1:
[Formula 1]

wherein the substituents, which are introduced into ring B, ring C or ring D and
represented by L to L , are independent from each other, even if they have the
same designations;

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M is selected from C, N and Si, with the proviso that if M is N, L or L is null;
Z is C;
each of a, a and a is independently selected from C, NR and O;
E is selected from the group consisting of SiMe2Ok2(CQ2)n2, SiEt2Ok2(CQ2)n2, SiF2
Ok2(CQ2)n2,SiCl2Ok2(CQ2)n2,SiMe2(CQ2)n2Ok2,SiEt2 (CQ2)n2Ok2,SiF2(CQ2)n2Ok2,
SiCl2(CQ2)n2Ok2,Ok2SiMe2(CQ2)n2,Ok2SiEt2(CQ2)n2,Ok2SiF2(CQ2)n2,Ok2SiCl2(CQ2
SiCl2(CQ2)n2Ok2,Ok2SiMe2(CQ2)n2,Ok2SiEt2(CQ2)n2,Ok2SiF2(CQ2)n2,Ok2SiCl2(CQ2
SiCl2(CQ2)n2Ok2,Ok2SiMe2(CQ2)n2,Ok2SiEt2(CQ2)n2,Ok2SiF2(CQ2)n2,Ok2SiCl2(CQ2
) SiEtO ,(CQ) SiFO ,(CQ) SiCl O ,(CH) , C=C, O, S, COO, OCO,
CF O, OCF, OCOO, CH O, CH CO, OCH and COCH, wherein k is 0 or 1, Q
is H or F, and n is an integer between 0 and 3;
R is selected from the group consisting of H, a C ~C alkyl group, a C ~C
alkene group and an alkoxy group (R O), wherein the alkene group is CH=CH,
CH=CHCH3 (E,Z), CH2CH=CH2, CH=CHCH2CH3 (E,Z), CH2CH=CHCH3
(E,Z),CHCHCH=CH,eH=eHCHCHCH (E^), CH CH=CI^frCH (E,Z),—
CH CH CH=CHCH (E,Z) or CH CH CH CH=CH ;
R is selected from the group consisting of H, a C ~C alkyl group and a C ~C
alkene group, wherein the alkene group is CH=CH, CH=CHCH (E,Z), CH
CH==CH2, CH=CHCH2CH3 (E,Z), CH2CH=CHCH3 (E,Z), CH2CH2CH=CH2,
CH=CHCHCHCH (E,Z), CH CH=CHCH CH (E,Z), CH CH CH=CHCH
(E,Z) or CH CH CH CH=CH ;
X is selected from the group consisting of H, SiR R R , CF , OCF, CN, NCS,
halogen atoms and R;
each of R , R and R is independently selected from R and halogen atoms;
each of L,L,L,L,L,L and L is independently selected from the group
consisting of H, halogen atoms, CN, CF, OCF and NCS;
each of o, p and q independently represents an integer between 0 and 2; and
at least one of E, A and X contains silicon.
[2] The silicon-containing compound according to claim 1, which has negative
dielectric anisotropy.
[3] The silicon-containing compound according to claim 1, which is a compound
represented by any one formula selected from the group consisting of formula
2~formula 10:
[Formula 2]


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wherein A is selected from the group consisting of SiMe O (CO ) , SiEt O
(CQ2) , SiF2Ok1(CQ2)n1, SiCl2Ok1 (CQ2)n1, SiMe2 (CQ2)n1 Ok1, SiEt2 (CQ2)n1 Ok1, SiF2
(CQ2) , SiF2Ok1(CQ2)n1, SiCl2Ok1 (CQ2)n1, SiMe2 (CQ2)n1 Ok1, SiEt2 (CQ2)n1 Ok1, SiF2
(CQ2) , SiF2Ok1(CQ2)n1, SiCl2Ok1 (CQ2)n1, SiMe2 (CQ2)n1 Ok1, SiEt2 (CQ2)n1 Ok1, SiF2
(CQ2) , SiF2Ok1(CQ2)n1, SiCl2Ok1 (CQ2)n1, SiMe2 (CQ2)n1 Ok1, SiEt2 (CQ2)n1 Ok1, SiF22
C=C, O, S, COO, OCO, CF O, OCF, OCOO, CH O, CH CO, OCH and COCH
2, wherein k is 0 or 1, Q is H or F, n is an integer between 0 and 3;
M is selected from C, N and Si, with the proviso that if M is N, L or L is null;
Z is C;
each of a, a and a is independently selected from C, NR and O;
E is selected from the group consisting of SiJVfeO^CQ^, SiEtO (CQ^, SiF2
O (CQ) ,SiClO (CQ) ,SiMe(CQ) O , SiEt (CQ) O ,SiF(CQ) O ,
SiCl (CQ2)n2Ok2,Ok2 SiMe2(CQ2)n2,Ok2 SiEt2(CQ2)n2,Ok2SiF2(CQ2)n2,Ok2SiCl2(CQ2
(CQ2)n2Ok2,Ok2 SiMe2(CQ2)n2,Ok2 SiEt2(CQ2)n2,Ok2SiF2(CQ2)n2,Ok2SiCl2(CQ2
SiMe2(CQ2)n2,Ok2 SiEt2(CQ2)n2,Ok2SiF2(CQ2)n2,Ok2SiCl2(CQ2
SiMe2(CQ2)n2,Ok2 SiEt2(CQ2)n2,Ok2SiF2(CQ2)n2,Ok2SiCl2(CQ2
CF O, OCF , OCOO, CH O, CH CO, OCH and COCH , wherein k is 0 or 1, Q
is H or F, and n is an integer between 0 and 3;
R is selected from the group consisting of H, a C ~C alkyl group, a C ~C
alkene group and an alkoxy group (R O), wherein the alkene group is CH=CH,
CH=CHCH (E,Z), CH CH=CH , CH=CHCH CH (E,Z), CH CH=CHCH
(E,Z), CH CH CH=CH , CH=CHCH CH CH (E,Z), CH CH=CHCH CH (E,Z),
CH CH CH=CHCH (E,Z) or CH CH CH CH=CH ;
R is selected from the group consisting of H, a C ~C alkyl group and a C ~C
alkene group, wherein the alkene group is CH=CH, CH=CHCH (E,Z), CH

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CH=CH, CH=CHCH2CH3 (E,Z), CH2CH=CHCH3 (E,Z), CH2CH2CH=CH2,
CH=CHCHCHCH (E,Z), CH CH=CHCH CH (E,Z), CH CH CH=CHCH
(E,Z) or CH CH CH CH=CH;
X is selected from the group consisting of H, SiR R R , CF , OCF, CN, NCS,
halogen atoms and R;
each of R, R and R is independently selected from R and halogen atoms;
each of L,L,L,L,L,L and L is independently selected from the group
consisting of H, halogen atoms, CN, CF, OCF and NCS; and
each of o, p and q independently represents an integer between 0 and 2.
[4] The silicon-containing compound according to claim 1, which is selected from
the group consisting of the following compounds:


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wherein A is selected from the group consisting of SiO (CQ) , Si(CQ ) O ,
(CO) O Si, (CO) SiO ,0 (CO) Si and O Si(CQ) ,andR,R ,R ,°R ,M,
a,a,a,L,L,L,L,L,L, and Xare the same as defined in claim 1.
[5] The silicon-containing compound as claimed in claim 1, which has
stereoisomers.
[6] The silicon-containing compound as claimed in claim 5, wherein the
stereoisomers of the silicon-containing compound are present in a ratio of trans-
isomer:cis-isomer of 85~100:15~0.
[7] A liquid crystal composition, which comprises at least one silicon-containing
compound as defined in any one of claims 1 to 6.
[8] The liquid crystal composition as claimed in claim 7, wherein each silicon-
containing compound is present irian amount of l~50 wt% based on 100 wt% of
the total weight of the composition.
[9] A liquid crystal display device, which comprises a liquid crystal layer prepared
from the liquid crystal composition as defined in claim 7.
[10] A method for preparing a silicon-containing compound, which is represented by
the following Reaction Scheme 1:
[Reaction Scheme 1]

wherein U is selected from SiO (CQ^, SiCCQp O , (CQ^O Si, and (CQ)
SiO , wherein k is 0 or 1, Q is H or F, and n is an integer between 0 and 3;
W is selected from Me, Et, F and Cl; and
ring B, R, E, X, L , L , L, L, L , L , o, and p are the same as defined in claim 1.
[11] A method for preparing a silicon-containing compound, which is represented by
the following Reaction Scheme 2:
[Reaction Scheme 2]

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wherein V is selected from the group consisting of H, Me, Et, F, Cl, OMe and
OEt; and
ring B, E, R, X, L , L , L , L , o, and p are the same as defined in claim 1.
[12] A method for preparing a silicon-containing compound, which is represented by
the following Reaction Scheme 3:

[Reaction Scheme 3]
wherein U is selected from SiO (CQ2) , Si(CQ ) O , (CQ ) O Si, and(CQ)
SiO , wherein k is 0 or 1, Q is H or F, and n is an integer between 0 and 3;
W is selected from Me, Et, F and Cl; and
ring B, R, E, X, L , L, L, L, L , L, o, and p are the same as defined in claim 1.
[13] A method for preparing a silicon-containing compound, which is represented by
the following Reaction Scheme 4:
[Reaction Scheme 4]

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wherein V is selected from the group consisting of H, Me, Et, F, Cl, OMe and
OEt; and
ring B, R, E, A, X, L , L , L , L , o, p and q are the same as defined in claim 1.
[14] A method for preparing a silicon-containing compound, which is represented by
the following Reaction Scheme 5:
[Reaction Scheme 5]

wherein U is selected from SiO (CQ) ,Si(CQ) O ,(CQ) O Si, and(CQ)
SiO , wherein k is 0 or 1, Q is H or F, and n is an integer between 0 and 3;
W is selected from Me, Et, F and Cl; and
ring B, R, E, X, L , L , L , L, L , L , o, p and q are the same as defined in claim
1.
[15] A method for preparing a silicon-containing compound, which is represented by
the following Reaction Scheme 6:
[Reaction Scheme 6]

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33
(54) Title: LIQUID CRYSTAL COMPOSITION COMPRISING NOVEL SILICON CONTAINING COMPOUNDS AND LIQ-
UID CRYSTAL DISPLAY DEVICE USING HIE SAME
(57) Abstract: Disclosed are a silicon-containing compound, a liquid crystal composition comprising the same compound, and a
liquid crystal display device comprising a liquid crystal layer prepared from the liquid crystal composition. The silicon-containing
compound, which forms the liquid crystal composition, has low viscosity and high negative (-) dielectric anisotropy. Therefore, it is
possible to provide a liquid crystal display device, which has a fast response time and can be driven at a low voltage.