Optically active compound, liquid crystal compositions containing the optically active compound, and liquid crystal display device

I! An optically active compound of the formula (1), ##STR1## wherein R.sup.1 is a linear alkyl group, each of X.sup.1 and X.sup.2 is a hydrogen atom or one of X.sup.1 and X.sup.2 is a hydrogen atom and the other is a fluorine atom, each of Y.sup.1 and Y.sup.2 is a hydrogen atom or one of Y.sup.1 and Y.sup.2 is a hydrogen atom and the other is a fluorine atom, m is an integer of 3 to 10, and C* is an asymmetric carbon atom, II! an anti-ferroelectric liquid crystal composition consisting essentially of the optically active compound of the above formula (1) and a compound of the formula (2), ##STR2## and III! a ferrielectric liquid crystal composition consisting essentially of the optically active compound of the formula (1) and a compound of the formula (3). ##STR3##

FIELD OF THE INVENTION 
The present invention relates to an optically active compound having a 
specific structure and liquid crystal compositions containing the 
compound. More specifically, it relates to a novel optically active 
compound useful as a component for a liquid crystal composition and two 
types of liquid crystal compositions containing the compound. One of the 
two types of the liquid crystal compositions refers to an 
anti-ferroelectric liquid crystal composition, and the other refers to a 
ferrielectric liquid crystal composition. Further, the present invention 
relates to a simple matrix liquid crystal display device and an active 
matrix liquid crystal display device both of which use the above liquid 
crystal compositions. 
PRIOR ART 
A liquid crystal display device (LCD) has been so far applied to various 
small-sized display devices owing to its low-voltage operability, low 
power consumption and thin display. With recent broadening of application 
and use of liquid crystal display devices to/in an information and office 
automation-related machine and equipment field and a television field, 
there are rapidly growing demands for high-performance, large-sized liquid 
crystal display devices having higher display capacity and higher display 
quality over existing CRT display devices. 
Meanwhile, a liquid crystal display device as a flat panel display is 
already superseding a conventional Braun tube display (CRT) mainly in the 
fields of portable machines and equipment. With the recent functional 
extension of personal computers and word processors and with the recent 
increase in the volume of data processing, LCD is as well required to have 
higher functions such as a higher display capacity, full-color display, a 
wide viewing angle, a high-speed response and a higher contrast. 
However, as long as a nematic liquid crystal available at present is used, 
even an active matrix-driven liquid crystal display device used in a 
liquid crystal television set finds it not easy to increase its size and 
decrease its production cost due to its complicated production process and 
low yield. In a simple matrix-driven STN liquid crystal display device, 
large display capacity driving is not necessarily easy and its response 
time is limited, so that video frame rate display is therefore difficult. 
Further, a display device using a nematic liquid crystal is beginning to 
find a serious problem in its narrow viewing angle. 
At present, therefore, it cannot be said that a nematic liquid crystal 
display device can satisfy demands toward the above a high-performance 
large-sized liquid crystal display device. 
Under the circumstances, it is a liquid crystal display device for which a 
ferroelectric liquid crystal is adapted that is attracting attention as a 
high-response liquid crystal display device. A surface stabilized 
ferroelectric liquid crystal (SSFLC) device disclosed by Clark and 
Lagerwall attracts attention in that it has a fast response and a wide 
viewing angle which have not been achieved in the past. Its switching 
characteristics have been studied in detail, and a number of ferroelectric 
liquid crystal compounds have been synthesized for optimizing various 
physical property constants. However, it has problems that its threshold 
characteristic is insufficient, that its contrast is low since its layer 
has a chevron structure, that the fast response is not achieved as is 
expected, that alignment control is difficult so that it is not easy to 
obtain the bistability which is one of the greatest characteristics of 
SSFLC, and that alignment destroyed by mechanical shock is difficult to 
restore. It is therefore required to overcome these problems for its 
practical use. 
In addition to the above, the development of devices having switching 
mechanisms different from that of SSFLC are also under way. Switching 
among tristable states of a liquid crystal substance having an 
anti-ferroelectric phase (to be referred to as "anti-ferroelectric liquid 
crystal substance" hereinafter) is also one of these new switching 
mechanisms (Japanese Journal of Applied Physics, Vol. 27, pp. L729, 1988). 
As described above, an anti-ferroelectric liquid crystal device has three 
stable states, i.e., two uniform states (Ur, Ul) observed in a 
ferroelectric device and a third state. Chandani et al reports that the 
above third state is an anti-ferroelectric phase (Japanese Journal of 
Applied Physics, vol. 28, pp. L1261, 1989 and Japanese Journal of Applied 
Physics, vol. 28, pp. L1265, 1989). 
The above switching among tristable states is the first characteristic of 
an anti-ferroelectric liquid crystal device. The second characteristic of 
the anti-ferroelectric liquid crystal device is that a sharp threshold 
value is present relative to an applied voltage. Further, it has a memory 
effect, which is the third characteristic of the anti-ferroelectric liquid 
crystal device. By utilizing these excellent characteristics, a simple 
matrix-driven liquid crystal display device having a fast response and a 
good contrast can be achieved. 
The anti-ferroelectric liquid crystal has another great characteristic in 
that its layer structure easily performs switching when an electric field 
is applied (Japanese Journal of Applied Physics, Vol. 28, pp. L119, 1989 
and Japanese Journal of Applied Physics, vol. 29, pp. L111, 1990). 
On the basis thereof, a liquid crystal display device free of defects and 
capable of self-restoring alignment can be produced, and a liquid crystal 
device having an excellent contrast can be achieved. 
Further, it has been demonstrated that analogue gradation caused by applied 
voltage, which is almost impossible for a ferroelectric liquid crystal 
device, is possible for an anti-ferroelectric liquid crystal device. 
Accordingly, it is made possible to shift toward a full-color display, and 
the importance of an anti-ferroelectric liquid crystal device is 
increasing (Preprints of The 4th Ferroelectric Liquid Crystal 
International Symposium, page 77, 1993). 
As described above, the anti-ferroelectric liquid crystal device is gaining 
reliable dominance, while it is desired to broaden a driving temperature 
range and further improve its response speed, and it is further desired to 
develop an anti-ferroelectric liquid crystal device having a smectic A 
phase. 
With regard to the response speed, there is a serious problem on a 
low-temperature side, particularly on the side of temperatures lower than 
room temperature. 
Practically, the response speed on the side of a low-temperature, e.g., at 
10.degree. C., is as low as 1/10 to 1/20 of that at room temperature. 
Attempts are therefore being made to change frequency or a driving voltage 
or to install a heater for the purpose of making the driving smoother on a 
low-temperature side. However, the changing of the frequency or the 
voltage has its limitation and has not yet fully compensated the poor 
characteristics of the liquid crystal. Further, when a heater is 
installed, the device shows a decrease in transmittance so that the 
contrast decreases. As a result, a device having a high display quality 
can not be expected to obtain. 
The anti-ferroelectric liquid crystal device has two switching processes, 
one from an anti-ferroelectric state to a ferroelectric state and the 
other from a ferroelectric state to an anti-ferroelectric state. The 
speeds of these two switching processes based on voltage, i.e., response 
speeds, are important factors for determining a display quality. 
The response speed from an anti-ferroelectric state to a ferroelectric 
state (to be referred to as "response speed I" hereinafter) is important 
since it is, for example, an addressing speed multiplexing driving so that 
it determines the number of scanning lines which constitute one frame in 
simple matrix driving of consecutive scanning. That is, as the response 
speed I increases, the number of scanning lines can be increased, so that 
a high-resolution device can be achieved. 
Further, concerning the response speed from a ferroelectric state to an 
anti-ferroelectric state (to be referred to as "response speed II" 
hereinafter), a required speed varies depending upon a design of a driving 
method of the device. For example, it alters according to the set voltage 
of an offset voltage. However, when the response speed II is too fast, a 
ferroelectric state can not be fully maintained (a light or dark state 
cannot be maintained), while when it is too slow, disadvantageously, no 
change from a ferroelectric state to an anti-ferroelectric state takes 
place (no rewriting from a light or dark state to a dark or light state 
can be performed). For the response speed II, an optimum response speed is 
set after a driving method is determined. 
As explained above, a fast response speed I is important for achieving a 
high-resolution device, and at the same time, it is preferred that the 
dependency of the response speed on temperature be low. 
Practically, the anti-ferroelectric liquid crystal device is desired to 
have a further improved response speed on a low temperature side, a 
broadened temperature range of an anti-ferroelectric phase and a presence 
of a smectic A phase. 
M. Nakagawa has shown that the response speed of an anti-ferroelectric 
liquid crystal depends upon the rotation viscosity of liquid crystal 
molecules (Masahiro Nakagawa, Japanese Journal of Applied Physics, 30, 
1759 (1991)). That is, with a decrease in viscosity, the response speed 
increases. 
Further, when the response speed relative to temperature is observed, the 
response speed starts to become slow around room temperature and lowers 
exponentially in the temperature range lower than room temperature. An 
anti-ferroelectric liquid crystal has a high viscosity since its liquid 
crystal phase is a smectic phase, so that its viscosity sharply increases 
on a low-temperature side, and it is presumed that the response speed 
sharply becomes slow due to the viscosity resistance thereof. 
In one specific method for overcoming the above problem, it is conceivable 
to make an attempt to improve the response speed by adding a compound 
having a relatively low viscosity to a liquid crystal composition to 
decrease the viscosity of the composition as a whole, and this method is 
considered to be the most practical solution at present. However, this 
method tends to drop the upper limit temperature of the anti-ferroelectric 
phase, and it poses a problem in respect of the temperature range of the 
anti-ferroelectric phase although the response speed is improved. 
When it is considered to use an anti-ferroelectric liquid crystal as a 
display, generally, the temperature of the device increases up to about 
40.degree. C. due to the heat of backlight. For normal driving of the 
device, therefore, the upper-limit temperature of the anti-ferroelectric 
phase is required to be at least 40.degree. C., and for obtaining 
excellent alignment, it is desired that a smectic A phase exists on the 
side of temperatures higher than this temperature. 
Further, on the low-temperature side, the device is required to be driven 
at at least 10.degree. C., and hence, the lower-limit temperature of the 
anti-ferroelectric phase is required to be at least 0.degree. C. 
SUMMARY OF THE INVENTION 
The present invention in one aspect has been made from the above points of 
view, and it is an object of the present invention to provide an 
anti-ferroelectric liquid crystal composition which secures an 
anti-ferroelectric phase in a wide temperature range and which exhibits an 
extremely fast response at a low temperature; and a liquid crystal display 
device thereof. 
It is another object of the present invention to provide an optically 
active compound as a component for the above anti-ferroelectric liquid 
crystal composition. 
According to studies by the present inventors, the above object of the 
present invention is achieved by an optically active compound of the 
formula (1), 
##STR4## 
wherein R.sup.1 is a linear alkyl group, each of X.sup.1 and X.sup.2 is a 
hydrogen atom or one of X.sup.1 and X.sup.2 is a hydrogen atom and the 
other is a fluorine atom, m is an integer of 3 to 10, and C* is an 
asymmetric carbon atom. 
The present inventors have made further studies, and as a result, have 
found that the object of the present invention is achieved by an 
anti-ferroelectric liquid crystal composition containing an optically 
active compound of the formula (1) and an anti-ferroelectric liquid 
crystal compound of the formula (2), 
##STR5## 
wherein, in the formula (1), R.sup.1, X.sup.1, X.sup.2 and m are as 
defined in the above formula (1), and in the formula (2), R.sup.2 is a 
linear alkyl group, each of Z.sup.1 and Z.sup.2 is a hydrogen atom or one 
of Z.sup.1 and Z.sup.2 is a hydrogen atom and the other is a fluorine 
atom, p is an integer of 5 to 8, q is an integer of 2 or 4, and C* is an 
asymmetric carbon atom.

DETAILED DESCRIPTION OF THE INVENTION 
The optically active compound and the anti-ferroelectric liquid crystal 
composition containing it, provided by the present invention, will be 
explained in detail hereinafter. 
In the optically active compound of the formula (1), R.sup.1 is a linear 
alkyl group, preferably a linear alkyl group having 6 to 12 carbon atoms. 
Each of X.sup.1 and X.sup.2 is a hydrogen atom, or one of these is a 
hydrogen atom and the other is a fluorine atom. In the latter case, 
preferably, X.sup.1 is a hydrogen atom and X.sup.2 is a fluorine atom. m 
is an integer of 3 to 10, preferably 3 to 8. C* is an asymmetric carbon 
atom. 
The optically active compound of the present invention can be easily 
produced by the following method. 
The method is outlined as follows. 
(a) R*OH+p--TsCl.fwdarw.R*OTs 
(b) Compound from (a)+p--HO--Ph--O--CH.sub.2 Ph .fwdarw.PhCH.sub.2 
--O--Ph--O--R* 
(c) Compound from (b)+H.sub.2 .fwdarw.HOPhO--R* 
(d) R.sup.1 COO--Ph--COOH+SOCl.sub.2 .fwdarw.R.sup.1 COO--Ph--COCl 
(e) Compound from (d)+Compound from (c) .fwdarw.Optically active compound 
In the above (a) to (e), R*OH is an optically active 2-alkanol, p-TsCl is 
p-toluenesulfonyl chloride, Ph is a 1,4-phenylene group (which may be 
substituted with fluorine in the 2- or 3-position), and PhCH.sub.2 -- is a 
benzyl group. R.sup.1 is as defined in the formula (1). 
The above production method will be briefly explained below. 
(a) Tosylation of optically active alcohol. 
(b) Reaction of a compound from (a) with p-benzyloxyphenol. 
(c) Hydrogenation of a compound from (b) to eliminate a benzyl group. 
(d) Chlorination of 4-carbonyloxybenzoic acid. 
(e) Reaction between a compound from (d) and a compound from (c) to 
synthesize an optically active compound as an end product. 
In the anti-ferroelectric liquid crystal compound of the above formula (2), 
R.sup.2 is a linear alkyl group, preferably a linear alkyl group having 6 
to 10 carbon atoms. Each of Z.sup.1 and Z.sup.2 is a hydrogen atom, or one 
of these is a hydrogen atom and the other is a fluorine atom. In preferred 
embodiments of Z.sup.1 and Z.sup.2, Z.sup.1 is a hydrogen atom and Z.sup.2 
is a fluorine atom. p is an integer of 5 to 8, preferably 5. q is an 
integer of 2 or 4, preferably 2. 
In the anti-ferroelectric liquid crystal composition of the present 
invention, the proportions of the optically active compound of the formula 
(1) and the anti-ferroelectric liquid crystal compound of the formula (2) 
are 5 to 40 mol % and 95 to 60 mol %, preferably 10 to 30 mol % and 90 to 
70 mol %, respectively. 
In the anti-ferroelectric liquid crystal composition of the present 
invention, the upper-limit temperature of the anti-ferroelectric phase is 
preferably at least 40.degree. C. in view of a temperature increase of the 
liquid crystal device caused by the heat of backlight. Further, since the 
liquid crystal device is required to be operable in the neighborhood of 
10.degree. C., desirably, the lower-limit temperature of the 
anti-ferroelectric phase is present at at least 0.degree. C. 
Further, the anti-ferroelectric liquid crystal composition of the present 
invention preferably has a smectic A phase present on a higher temperature 
than that of the anti-ferroelectric phase in view of the alignment 
properties. 
The anti-ferroelectric liquid crystal composition of the present invention 
is interposed between substrates having scanning electrodes and signal 
electrodes arranged in a matrix form, and used as a simple matrix liquid 
crystal display device. In this display device, the driving by voltage can 
be switched among one anti-ferroelectric state and two ferroelectric 
states by a simple matrix driving method. 
The anti-ferroelectric liquid crystal compound of the formula (2) used in 
the present invention can be easily produced, for example, by the 
following method. 
(i) AcO--Ph(2X)--COOH+SOCl.sub.2 .fwdarw.AcO--Ph(2X)--COCl 
(ii) Compound from (i)+HOC*H(CF.sub.3)--(CH.sub.2).sub.p OC.sub.q 
H.sub.2q+1 .fwdarw.AcO--Ph(2X)--COO--C*H(CF.sub.3)--(CH.sub.2).sub.p 
OC.sub.q H.sub.2q+1 
(iii) Compound from (ii)+(Ph--CH.sub.2 NH.sub.2) 
.fwdarw.HO--Ph(2X)--COO--C*H(CF.sub.3)--(CH.sub.2).sub.p OC.sub.q 
H.sub.2q+1 
(iv) R.sup.2 O--Ph--Ph--COOH+SOCl.sub.2 .fwdarw.R.sup.2 O--Ph--Ph--COCl 
(v) Compound from (iii)+compound from (iv) .fwdarw.Anti-ferroelectric 
liquid crystal compound 
In the above (i) to (v), Ph is a 1,4-phenylene group, Ph(X) is a 
1,4-phenylene group (which maybe substituted with fluorine on the 2- or 
3-position), Ac is an acetyl group, and R.sup.2, p and q are as defined in 
the formula (2). 
The above production method will be briefly explained below. 
(i) Formation of an acid chloride by the chlorination of 
fluorine-substituted or non-substituted p-acetoxybenzoic acid with thionyl 
chloride. 
(ii) Formation of an ester by a reaction of the acid chloride (i) with an 
optically active alcohol. 
(iii) Deacetylation of the ester from (ii). 
(iv) Formation of an acid chloride of alkyloxybiphenylcarboxylic acid. 
(v) Formation of a liquid crystal compound by a reaction of a compound from 
(iii) with the acid chloride from (iv). 
As explained above, the present invention provides the novel optically 
active compound (formula (1)), and further provides an anti-ferroelectric 
composition containing the above optically active compound. This 
anti-ferroelectric composition has an anti-ferroelectric phase in a broad 
temperature range and exhibits a fast response at temperatures lower than 
room temperature. There can be therefore obtained an anti-ferroelectric 
liquid crystal display device having a high display quality. 
The present inventors have made further studies, and as a result, have 
found that a composition prepared by blending the optically active 
compound of the above formula (1) with a specific ferrielectric liquid 
crystal compound has excellent characteristics as an active matrix liquid 
crystal display device. 
A conventional ferrielectric liquid crystal display device will be 
explained below, and thereafter, the ferrielectric liquid crystal 
composition and the ferrielectric liquid crystal display device, provided 
by the present invention, will be explained. 
As a liquid crystal display mode (liquid crystal driving method) having 
higher functions such as higher display capacity, full-color display, wide 
viewing angle and high-speed response over a conventional liquid crystal 
display device (LCD), there has been proposed and practically used an 
active matrix (AM) display device which works by a method in which thin 
film transistors (TFT) or diodes (MIM) are formed such that one transistor 
or diode corresponds to one pixel on a display screen and a liquid crystal 
is driven for each pixel independently of every other one. The above 
display mode has problems in that it is difficult to decrease a cost due 
to a low yield and that it is difficult to provide a large display screen. 
However, due to a high display quality, the above display mode is about to 
surpass an STN method which has been a conventional mainstream and to 
overtake CRT. 
However, the above AM display device has the following problems since it 
uses a TN (twisted nematic) liquid crystal as a liquid crystal material. 
(1) A TN liquid crystal is a nematic liquid crystal, and the response speed 
is generally low (tens ms). In the display of video frame rate, no good 
display quality can be obtained. 
(2) A twisted state (twist alignment) of liquid crystal molecules is used 
for displaying, and the viewing angle is therefore narrow. In a 
gray-scaling display in particular, the viewing angle is sharply narrowed. 
That is, the contrast ratio and the color change depending upon viewing 
angles to a display screen. 
For overcoming the above problems, in recent years, there have been 
proposed AM panels which use a ferroelectric liquid crystal or an 
anti-ferroelectric liquid crystal in place of the TN liquid crystal 
(Japanese Laid-open Patent Publications Nos. 249502/1993, 150257/1993 and 
95080/1994). However, these AM panels have the following problems, which 
constitute practically barriers against putting them into practical use. 
(1) A ferroelectric liquid crystal has spontaneous polarization. An image 
sticking is liable to take place due to a constant presence of the 
spontaneous polarization, and the driving is made difficult. In a display 
by a surface-stabilized mode, it is very difficult to perform a 
gray-scaling display since only a binary display of black and white is 
possible. For a gray-scaling display, a special devising is required 
(e.g., ferroelectric liquid crystal device using monostability); Keiichi 
NITO et al., SID '94, Preprint, p.48), and it is required to develop a 
very high technique for practical use. 
(2) An anti-ferroelectric liquid crystal is free of the problem of image 
sticking described in the above (1) since it has no permanent spontaneous 
polarization. 
Meanwhile, the AM driving requires a liquid crystal material which can be 
driven at a low voltage of at least 10V or less. However, the 
anti-ferroelectric liquid crystal generally shows a high threshold 
voltage, and it is therefore difficult to drive at a low voltage. Further, 
it has a problem that a gray-scaling display is difficult since its 
optical response involves a hysteresis. 
It is an object of the present invention to provide a novel material which 
can overcome the above problems and is suitable for AM driving. A 
ferrielectric liquid crystal is conceivable as the above novel material. 
A ferrielectric phase (SC.gamma.* phase)was found in 
4-(1-methylheptyloxycarbonyl)phenyl 4-(4-octyloxyphenyl)benzoate (to be 
abbreviated as "MHPOBC" hereinafter) in 1989 for the first time (Japanese 
Journal of Applied Physics, Vol. 29, No. 1, 1990, pp. L131-137). 
MHPOBC has the following structural formula and phase sequence. 
Structure formula: 
EQU C.sub.8 H.sub.17 --O--Ph--Ph--COO--Ph--COO--C*H(CH.sub.3) C.sub.6 H.sub.13 
wherein Ph is a phenylene group and C* is an asymmetric carbon atom. 
Phase sequence: 
Cr(30)SIA*(65)SCA*(118)SC.gamma.*(119)SC*(121)SC.alpha.*(122)SA(147)I 
wherein Cr is a crystal phase, SIA* is a chiral smectic IA phase, SCA* is a 
chiral smectic CA phase (anti-ferroelectric phase), SC.gamma.* is a chiral 
smectic C.gamma. phase (ferrielectric phase), SC* is a chiral smectic C 
phase (ferroelectric phase), SC.alpha.* is a chiral smectic C.alpha. 
phase, SA is a smectic A phase, I is an isotropic phase, and parenthesized 
values are phase transition temperatures (.degree.C.). 
For explaining the ferrielectric liquid crystal, FIG. 1 shows a molecular 
arrangement state of the ferrielectric phase, and FIG. 2 shows an optical 
response of the ferrielectric phase to a triangular wave. 
The ferrielectric phase has a molecular arrangement FI(+) or FI(-) as shown 
in FIG. 1. In a state where no electric field is present, FI(+) and FI(-) 
are co-present since FI(+) and FI(-) are equivalent. Average optic axes 
are therefore in the direction of a layer normal, and a dark state is 
brought under the condition of polarizers shown in FIG. 1. 
The above state corresponds to a site where an applied voltage is 0 and the 
intensity of transmittance is 0 in FIG. 2. 
Further, each of FI(+) and FI(-) has spontaneous polarization as is clear 
in molecular arrangement states, and in a state where these are 
co-present, the spontaneous polarizations are cancelled, which causes an 
average spontaneous polarization of zero. Like an anti-ferroelectric 
phase, the ferrielectric phase is therefore free from an image sticking 
phenomenon found in a ferroelectric liquid crystal. 
As an electric field is applied to a ferrielectric liquid crystal, a domain 
having an extinguished position appears at a voltage lower than that at 
which a ferroelectric state is reached. This shows that the domain has an 
optic axis in a direction tilted apart from the direction of a layer 
normal although it is not so tilted as in a ferroelectric state. The above 
intermediate state is considered to be FI(+) or FI(-). In this case, not a 
continuous change but a stepwise change in the intensity of transmittance 
could be observed between voltages 0V and 4V in FIG. 2. In FIG. 2, 
however, a continuous change in the intensity of transmittance was 
observed. This is presumably because the threshold voltage of 
FI(+).fwdarw.FO(+) or FI(-).fwdarw.FO(-) is not clear. 
In the present invention, a liquid crystal phase in which the above 
intermediate state is always observed refers to a ferrielectric phase, and 
a liquid crystal compound in which the temperature range of the 
ferrielectric phase is the broadest among liquid crystal phases refers to 
a ferrielectric liquid crystal. 
When the applied voltage is further increased, the ferrielectric phase 
causes phase transition to a ferroelectric phase FO(+) or FO(-), which is 
a stable state, depending upon a direction of an electric field. That is, 
in FIG. 2, a phase in which the intensity of transmittance is brought into 
a saturated state (left and right flat portions in FIG. 2) is FO(+) or 
FO(-). 
It is seen in FIG. 1 that the above ferroelectric state FO(+) or FO(-) has 
a greater spontaneous polarization than the ferrielectric state FI(+) or 
FI(-). As explained above, in the ferrielectric phase, a state where FI(+) 
and FI(-) are co-present is used as "dark", and ferroelectric states FO(+) 
and FO(-) are used as "light". 
A conventional ferroelectric liquid crystal permits switching between FO(+) 
and FO(-), while a ferrielectric phase has a major characteristic feature 
in that it permits switching among four states, FO(+), FI(+), FI(-) and 
FO(-). 
Meanwhile, the principle of each liquid crystal display uses birefringence 
of a liquid crystal, and a display device of which the viewing angle 
dependency is small can be fabricated. 
As shown in FIG. 2, generally, the ferrielectric phase has a small 
difference between the voltage required for a change from a ferrielectric 
state to a ferroelectric state and the voltage required for a change from 
a ferroelectric state to a ferrielectric state. That is, the 
characteristics of the ferrielectric phase is that it has a strong 
tendency that the width of its hysteresis is narrow and that it shows a 
V-letter-shaped optical response, and the ferrielectric phase is suitable 
for AM driving and a gray-scaling display in AM driving. Further, in a 
change based on voltage, the ferrielectric liquid crystal has a tendency 
that the threshold voltage for a change from a ferrielectric state to a 
ferroelectric state is much smaller than that of an anti-ferroelectric 
liquid crystal, which also proves that the ferrielectric liquid crystal is 
suitable for AM driving. 
However, few liquid crystal compounds having a ferrielectric phase have 
been so far synthesized, and none of known liquid crystal compounds having 
a ferrielectric phase are satisfactory in view of the ferrielectric phase 
temperature range, hysteresis and threshold voltage when the above liquid 
crystal compounds alone are applied to an AM drive device. 
For example, generally, the drive voltage in an AM drive device is low, and 
it is required to drive the AM drive device at a high speed at an applied 
voltage of 10 V or less. When viewed from this aspect, conventionally 
obtained liquid crystal compounds having a ferrielectric phase have a 
drawback in response at a drive voltage of 10 V or less, and it has been 
strongly desired to improve the compounds in this aspect. 
The present invention has been made from the above points of view, and it 
is an object of the present invention to provide a liquid crystal 
composition which is excellent in driving at a low voltage suitable for 
use with AM driving and has a novel ferrielectric phase, by incorporating 
the above optically active compound having the specific structure into a 
specific ferrielectric liquid crystal compound. 
According to the present invention, therefore, there is provided a 
ferrielectric liquid crystal composition consisting essentially of the 
optically active compound of the formula (1) and a ferrielectric liquid 
crystal compound of the formula (3). 
##STR6## 
wherein, in the formula (1), R.sup.1, X.sup.1, X.sup.2 and m are as 
defined in the formula (1), and in the formula (3), R.sup.3 is a linear 
alkyl group, each of W.sup.1 and W.sup.2 is a hydrogen atom or one of 
these is a hydrogen atom and the other is a fluorine atom, r is an integer 
of 2 to 4, t is an integer of 2 to 4, and C* is asymmetric carbon atom. 
The optically active compound of the formula (1), contained in the above 
ferrielectric liquid crystal composition of the present invention, is the 
same as the optically active compound of the formula (1) used in the 
afore-mentioned anti-ferroelectric liquid crystal composition. In the 
optically active compound of the formula (1) contained in the 
ferrielectric liquid crystal composition, R.sup.1 is a linear alkyl group, 
preferably a linear alkyl group having 8 to 10 carbon atoms. m is an 
integer of 3 to 10, preferably 3 to 8. X.sup.1 and X.sup.2 are as defined 
above. 
Further, in the ferrielectric compound of the formula (3) contained in the 
ferrielectric liquid crystal composition, R.sup.3 is a linear alkyl group, 
preferably a linear alkyl group having 7 to 12 carbon atoms. Each of 
W.sup.1 and W.sup.2 is a hydrogen atom, or one of these is a hydrogen atom 
and the other is a fluorine atom. r is an integer of 2 to 4, preferably 3. 
t is an integer of 2 to 4, preferably 2. 
In the ferrielectric liquid crystal composition of the present invention, 
the proportions of the optically active compound of the formula (1) and 
the ferrielectric liquid crystal compound of the formula (3) are 1 to 60 
mol % and 99 to 40 mol %, preferably 10 to 50 mol % and 90 to 50 mol %. 
In the ferrielectric liquid crystal composition of the present invention, 
preferably, the phase transition temperature of the ferrielectric phase on 
the high-temperature side is at least 40.degree. C., and the phase 
transition temperature on the low-temperature side is 0.degree. C. or 
lower. Particularly preferably, the phase transition temperature on the 
high temperature side is at least 50.degree. C. Further, in the 
ferrielectric liquid crystal composition, preferably, a smectic A phase is 
present at a temperature higher than the temperature at which it shows the 
ferrielectric phase. 
In the ferrielectric phase, further, the threshold voltage for a transition 
from the ferrielectric phase to the ferroelectric phase is preferably 5 
V/.mu.m or less, more preferably 3 V/.mu.m or less. 
The above ferrielectric liquid crystal composition of the present invention 
is used as an active matrix liquid crystal display device by interposing 
it between substrates provided with non-linear active elements such as 
thin film transistors or diodes provided for each of pixels. And, the 
active matrix liquid crystal device can be used as one in which the 
driving by a voltage of a liquid crystal with non-linear active elements 
is performed by switching among two ferrielectric states, two 
ferroelectric states and intermediate states therebetween. 
The ferrielectric liquid crystal compound of the general formula (3), used 
in the present invention, can be easily produced by the method outlined 
below. 
(i) AcO--Ph(X)--COOH+SOCl.sub.2 .fwdarw.AcO--Ph(X)--COCl 
(ii) Compound from (i)+CF.sub.3 C*H (OH)(CH.sub.2).sub.r OC.sub.t 
H.sub.2t+1 .fwdarw.AcO--Ph(X)--COO--C*H(CF.sub.3)(CH.sub.2).sub.r OC.sub.t 
H.sub.2t+1 
(iii) Compound from (ii)+(Ph--CH.sub.2 NH.sub.2) 
.fwdarw.HO--Ph(X)--COO--C*H(CF.sub.3)(CH.sub.2).sub.r OC.sub.t H.sub.2t+1 
(iv) R.sup.3 --O--Ph--Ph--COOH+SOCl.sub.2 .fwdarw.R.sup.3 --O--Ph--Ph--COCl 
(v) Compound from (iii)+Compound from (iv) .fwdarw.Ferrielectric liquid 
crystal 
In the above (i) to (v), Ph is a 1,4-phenylene group, Ph(X) is a 
1,4-phenylene group (which may be substituted with a fluorine atom on its 
2- or 3-position), and R.sup.3, r and t are as defined in the formula (3). 
The above production method is briefly explained as below. 
(i) p-Acetoxybenzoic acid is chlorinated with thionyl chloride. 
(ii) The chlorinated product from (i) and an optically active alcohol are 
allowed to react to form an ester. 
(iii) The ester from (ii) is deacetylated. 
(iv) 4'-Alkyloxybiphenyl-4-carboxylic acid is chlorinated. 
(v) The phenol from (iii) and the chlorinated product from (iv) are allowed 
to react to form a liquid crystal compound. 
The novel ferrielectric liquid crystal composition consisting essentially 
of the optically active compound of the formula (1) and the ferrielectric 
liquid crystal compound of the formula (3) has a ferrielectric phase in a 
wide temperature range and exhibits a fast response at a temperature lower 
than room temperature, and it therefore has an excellent value as a 
material for a liquid crystal display device. 
EXAMPLES 
The present invention will be further specifically explained with reference 
to Examples, while the present invention shall not be limited thereto. 
Example 1 
(Formula (1): R.sup.1 =C.sub.9 H.sub.19, X.sup.1 =H, X.sup.2 =F, m=5 (E1) 
Preparation of 
(+)-4-(1-methylhexyloxy)phenyl=2'-fluoro-4'-decanoyloxyphenylbenzoate 
(1) Preparation of 1-methylhexyl (+)-p-toluenesulfonate 
A reactor was charged with 3.48 g of R-(-)-2-heptanol and 15 
ml(milliliters) of pyridine, and the mixture was cooled to -20.degree. C. 
While the mixture was stirred, 6.3 g of p-toluenesulfonyl chloride was 
added at a time, the mixture was stirred at this temperature for 30 
minutes, and then, the stirring was continued for further 4 hours at room 
temperature. The reaction mixture was poured into ice water and extracted 
with dichloromethane. An organic layer was washed with water and dried 
over anhydrous sodium sulfate. The solvent was distilled off to give 6 g 
(yield 74%) of the end product. 
(2) Preparation of (+)-4-benzyloxyphenyl-1-methylhexyl ether 
A reactor was charged with 6 g of the 1-methylhexyl (+)-p-toluenesulfonate 
obtained in (1), 4.47 g of hydroquinone monobenzyl ether, 2.38 g of 
potassium hydroxide and 28 ml of ethanol, and the mixture was stirred at 
room temperature for 2 hours. Then, the mixture was further refluxed under 
heat for 1 hour. The reaction mixture was poured into water and extracted 
with dichloromethane, and an organic layer was washed with 1N hydrochloric 
acid and with water, and dried over anhydrous sodium sulfate. The solvent 
was distilled off to give a crude product. The crude product was purified 
by silica gel column chromatography (eluent; hexane/ethyl acetate=925/75) 
to give 14.9 g (yield 67%) of the end product. 
(3) Preparation of (+)-4-(1-methylhexyloxy)phenol 
A reactor was charged with 0.2 g of a 10% palladium-carbon catalyst and 
then, the atmosphere in the system was purged with nitrogen gas. 4.46 
Grams of the benzyl ether obtained in (2) and 30 ml of ethanol were added 
thereto, and the atmosphere in the system was purged with hydrogen gas. 
While hydrogen gas was fed through a gas buret, the mixture was allowed to 
react for 8 hours. The atmosphere in the system was purged with nitrogen 
gas and then, the catalyst was separated off by filtration, and the 
solvent was distilled off to give 3 g (yield 97%) of the end product. 
(4) Preparation of 
(+)-4-(1-methylhexyloxy)phenyl=2'-fluoro-4'-decanoyloxyphenylbenzoate 
A reactor was charged with 1.04 g of 2-fluoro-4-decanoyloxybenzoic acid and 
20 ml of thionyl chloride, and the mixture was refluxed under heat for 4 
hours. Excessive thionyl chloride was distilled off under reduced 
pressure. The residue was dissolved in toluene, and washed with 
hydrochloric acid, with a sodium hydroxide aqueous solution and with water 
in this order. The solvent was distilled off, and the resultant crude 
product was purified by silica gel column chromatography (eluent; 
hexane/ethyl acetate=94/6). 
The yield of the product was 0.63 g (yield 61%). 
Examples 2 and 3 
(Formula (1): R.sup.1 =C.sub.9 H.sub.19, X.sup.1 =H, X.sup.2 =F, m=3 (E2)) 
Preparation of 
(+)-4-(1-methylbutyloxy)phenyl=2'-fluoro-4'-decanoyloxyphenylbenzoate, and 
(Formula (1): R.sup.1 =C.sub.9 H.sub.19, X.sup.1 =H, X.sup.2 =F, m=7 (E3)) 
Preparation of 
(+)-4-(1-methyloctyloxy)phenyl=2'-fluoro-4'-decanoyloxyphenylbenzoate 
The end products were obtained in the same manner as in Example 1 except 
that the R-(-)-2-heptanol used in Example 1 was replaced with 
R-(-)-pentanol or R-(-)-nonanol. 
Example 4 
(Formula (1): R.sup.1 =C.sub.9 H.sub.19, X.sup.1 =H, X.sup.2 =H, m=5 (E4)) 
Preparation of (+)-4-(1-methylhexyloxy)phenyl=4'-decanoyloxyphenylbenzoate 
The end product was obtained in the same manner as in Example 1 except that 
the .sup.2 -fluoro-4-decanoyloxybenzoic acid used in Example 1 was 
replaced with 4-decanoyloxybenzoic acid. 
Example 5 
(Formula (1): R.sup.1 =C.sub.10 H.sub.21, X.sup.1 =H, X.sup.2 =H, m=5 (E5)) 
Preparation of 
(+)-4-(1-methylhexyloxy)phenyl=4'-undecanoyloxyphenylbenzoate 
The end product was obtained in the same manner as in Example 4 except that 
the 4-decanoyloxybenzoic acid used in Example 4 was replaced with 
4-undecanoyloxybenzoic acid. 
Example 6 
(Formula (1): R.sup.1 =C.sub.6 H.sub.13, X.sup.1 =H, X.sup.2 =F, m=5 (E6)) 
Preparation of 
(+)-4-(1-methylhexyloxy)phenyl=4'-heptanoyloxy-2'-fluorobenzoate 
The end product, 
(+)-4-(1-methylhexyloxy)phenyl=4'-heptanoyloxy-2'-fluorobenzoate, was 
obtained in the same manner as in Example 1 except that the 
2-fluoro-4-decanoyloxybenzoic acid used in Example 1 was replaced with 
2-fluoro-4-heptanoyloxybenzoic acid. 
Example 7 
(Formula (1): R.sup.1 =C.sub.9 H.sub.19, X.sup.1 =f, X.sup.2 =H, m=5 (E7)) 
Preparation of 
(+)-4-(1-methylhexyloxy)phenyl=4'-decanoyloxy-3'-fluorobenzoate 
The end product, 
(+)-4-(1-methylhexyloxy)phenyl=4'-decanoyloxy-3'-fluorobenzoate, was 
obtained in the same manner as in Example 1 except that the 
2-fluoro-4-decanoyloxybenzoic acid used in Example 1 was replaced with 
3-fluoro-4-decanoyloxybenzoic acid. 
Table 1 shows NMR spectrum data of the end products obtained in Examples 1 
to 7. 
Further, liquid crystal phases were identified by texture observation and 
DSC (differential scanning calorimeter). Table 2 shows the results, and 
structural formulae of the compounds (E1) to (E7) are shown subsequently 
to the above Table 2. 
TABLE 1 
______________________________________ 
Hydrogen 
atom No. 1 2 3 4 5 6 7 8 9 
______________________________________ 
E1 (.delta., ppm) 
0.9 2.6 7.0 7.0 8.2 7.2 6.9 4.3 0.9 
E2 0.9 2.6 7.0 7.0 8.2 7.2 6.9 4.4 0.9 
E3 0.9 2.6 7.0 7.0 8.2 7.2 6.9 4.4 0.9 
E4 0.9 2.6 7.3 8.2 7.1 6.9 4.4 0.9 -- 
E5 0.9 2.6 7.3 8.2 7.1 6.9 4.4 0.9 -- 
E6 0.9 2.6 7.0 7.0 8.1 7.1 6.9 4.4 -- 
E7 0.9 2.6 8.0 7.3 8.0 7.1 6.9 4.3 -- 
______________________________________ 
TABLE 2 
______________________________________ 
Compound No. Phase sequence 
______________________________________ 
E1 I(22)SA(-9)Cr 
E2 I(22)SA(-1)Cr 
E3 I(20)SA(-7)Cr 
E4 I(27)SA(17)Cr 
E5 I(30)SA(22)Cr 
E6 I(9)Cr 
E7 I(8.8)Cr 
______________________________________ 
In the above phase sequences, parenthesized values show transition 
temperatures (unit; .degree.C.), I is an isotropic phase, SA is a smectic 
A phase, and Cr is a crystal phase. 
##STR7## 
Examples 8-10 
The optically active compound (E1) obtained in Example 1 in an amount of 10 
mol %, 20 mol % or 30 mol % was mixed with an anti-ferroelectric liquid 
crystal (2A) having the following chemical formula, to obtain 
compositions. 
EQU 2A: C.sub.9 H.sub.19 
--O--Ph--Ph--COO--Ph(3F)--COO--C*H(CF.sub.3)(CH.sub.2).sub.5 OC.sub.2 
H.sub.5 
wherein Ph is a 1,4-phenylene group, Ph(3F) is a 1,4-phenylene group having 
a fluorine atom substituted on the 3-position (=Y), and C* is asymmetric 
carbon atom. 
Examples 11 and 12 
The anti-ferroelectric liquid crystal (2A) used in Example 8 was mixed with 
30 mol % of the optically active compound (E4) obtained in Example 4 or 
with 23 mol % of the optically active compound (E5) obtained in Example 5, 
to obtain compositions. 
Examples 13 and 14 
The anti-ferroelectric liquid crystal (2A) used in Example 8 was mixed with 
30 mol % of the optically active compound (E6) obtained in Example 6 or 
with 30 mol % of the optically active compound (E7) obtained in Example 7, 
to obtain compositions. 
Example 15 
An anti-ferroelectric liquid crystal (2B) having the following chemical 
formula was mixed with 30 mol % of the optically active compound (E6) 
obtained in Example 6, to obtain a composition. 
EQU 2B: C.sub.8 H.sub.17 
--O--Ph--Ph--COO--Ph(3F)--COO--C*H(CF.sub.3)(CH.sub.2).sub.5 OC.sub.2 
H.sub.5 
The liquid crystal compositions obtained in Examples 6 to 15 were 
identified for phases, and measured for response times. Table 3 shows the 
results. 
The liquid crystal phases of the compositions were identified by texture 
observation and DSC (differential scanning calorimeter). 
Further, the response times were measured as follows. 
A liquid crystal cell (cell thickness 1.8 .mu.m) having a rubbed polyimide 
thin film and ITO electrode was filled with a composition in an isotropic 
state. The cell was gradually cooled at a rate of 1.degree. C./minute to 
align the liquid crystal in a smectic A phase (SA phase). The cell was 
placed between polarizer plates crossing each other at right angles, such 
that the layer direction of the liquid crystal was in parallel with an 
analyzer or a polarizer. 
The minimum intensity of transmitted light was taken as 0%, and the maximum 
intensity thereof was taken as 100%. While a step voltage having a 
frequency of 10 Hz and a voltage of 50 V was applied to the liquid crystal 
cell, the time required for the intensity of transmitted light changing to 
90% at the time of switching from an anti-ferroelectric state to a 
ferroelectric state was taken as response time I, and the time required 
for the intensity of transmitted light changing to 90% at the time of 
switching from a ferroelectric state to an anti-ferroelectric state was 
taken as response time II. These response times were measured. The 
measurements were all conducted at 10.degree. C. 
TABLE 3 
__________________________________________________________________________ 
Compo- 
sition 
and Response 
Measure- 
Example 
Molar time ment tem- 
No. ratio 
Phase sequence 
I II perature 
__________________________________________________________________________ 
8 2A/E1 = 
I(77)SA(67)SCA*(&lt;-10)Cr 
70 58200 
10.degree. C. 
90/10 
9 2A/E1 = 
I(75)SA(59)SCA*(&lt;-10)Cr 
49 72400 
10.degree. C. 
80/20 
10 2A/E1 = 
I(72)SA(52)SCA*(&lt;-10)Cr 
40 74500 
10.degree. C. 
70/30 
11 2A/E4 = 
I(75)SA(57)SCA*(&lt;-10)Cr 
47 69000 
10.degree. C. 
70/30 
12 2A/E5 = 
I(75)SA(52)SCA*(&lt;-10)Cr 
45 13100 
10.degree. C. 
77/23 
13 2A/E6 = 
I(75)SA(51)SCA*(&lt;-50)Cr 
39 2600 
10.degree. C. 
70/30 
14 2A/E7 = 
I(69)SA(53)SC*(50)SCA*(&lt; 
62 5400 
10.degree. C. 
70/30 
-50)Cr 
15 2B/E6 = 
I(81)SA(55)SCA*(&lt;-20)Cr 
44 7635 
10.degree. C. 
70/30 
Compound I(83)SC*(77)SCA*(&lt;-50)Cr 
79 20200 
10.degree. C. 
2A 
Compound I(90)SCA*(&lt;-20)Cr 
141 
7635 
10.degree. C. 
2B 
__________________________________________________________________________ 
In Table 3, in "Phase sequence", parenthesized values show transition 
temperatures (.degree.C.), I is an isotropic phase, SA is a smectic A 
phase, SCA* is an anti-ferroelectric phase, SC* is a ferroelectric phase, 
and Cr is a crystal phase. 
Further, the unit in "Response time I" and "Response me II" is .mu. second. 
Examples 16 and 17 
A phenyl ester compound (E1) having the following chemical structure in an 
amount of 30 mol % or 40 mol % was mixed with a ferrielectric liquid 
crystal (3A) having the following chemical structure. 
EQU E1: C.sub.9 H.sub.19 --COO--Ph(2F)--COO--Ph--O--C*H(CH.sub.3)C.sub.5 
H.sub.11 
EQU 3A: C.sub.9 H.sub.19 
--O--Ph--Ph--COO--Ph(3F)--COO--C*H(CF.sub.3)(CH.sub.2).sub.3 OC.sub.2 
H.sub.5 
wherein Ph is a 1,4-phenylene group, Ph(2F) is a 1,4-phenylene group having 
a fluorine atom substituted on the 2-position (X.sup.2), Ph(3F) is a 
1,4-phenylene group having a fluorine atom substituted on the 3-position 
(W.sup.2), and C* is asymmetric carbon atom. 
Examples 18 and 19 
A phenyl ester compound having the following chemical structure (E2 or E3) 
in an amount of 40 mol % was mixed with the same ferrielectric liquid 
crystal (3A) as that used in Example 16. 
EQU E2: C.sub.9 H.sub.19 --COO--Ph(2F)--COO--Ph--O--C*H(CH.sub.3)C.sub.3 
H.sub.7 
EQU E3: C.sub.9 H.sub.19 --COO--Ph(2F)--COO--Ph--O--C*H(CH.sub.3)C.sub.7 
H.sub.15 
The compositions obtained in Examples 16 to 19 were identified for phases 
and measured for response times. Table 4 shows the results. 
The liquid crystal composition was identified for liquid crystal phases by 
texture observation, conoscopic image observation, DSC (differential 
scanning calorimeter) measurement, and confirmation of a domain having an 
extinguished position between the direction of a layer normal and the 
direction of an optic axis in a ferroelectric state (observation of a 
intermediate state FI(.+-.)). 
The observation of a conoscopic image is effective means of identifying a 
ferrielectric phase. The conoscopic image observation was conducted 
according to a piece of literature (J. Appl. Phys. 31, 793 (1992)). 
On the basis of the texture observation by general parallel alignment cell 
and the conoscopic image observation and DSC measurement, and on the basis 
of the observation of an intermediate state, i.e., an observed domain 
having an extinguished position between the direction of a layer normal 
and the direction of an optic axis in a ferroelectric state, the phase 
sequence of the liquid crystal compositions in Examples were identified. 
A cell for measuring the optical response was prepared in the following 
procedures. 
Glass plates with insulating film (SiO.sub.2, thickness; 50 nm) and ITO 
electrodes were coated with polyimide (thickness; about 80 nm), and one of 
a pair of the glass plates was rubbed. The pair of glass plates were 
attached to each other through a spacer having a particle diameter of 1.6 
.mu.m to form a test cell. The cell thickness was 2 .mu.m. The liquid 
crystal composition was heated until the liquid crystal showed an 
isotropic phase and then, the liquid crystal was injected into the test 
cell by capillarity. Then, the cell was gradually cooled at a rate of 
1.degree. C./minute to align the liquid crystal in parallel. 
Then, the test cell was driven by applying a triangular wave voltage of 
.+-.10 V, 50 mHz, to the test cell to study a change in transmitted light. 
When the minimum intensity of the transmitted light was taken as 0% and the 
maximum intensity of the transmitted light was taken as 100%, the voltage 
at which the intensity of transmitted light became 90% by phase transition 
from a ferrielectric phase to a ferroelectric phase was defined as 
threshold voltage I (unit: V/.mu.m), and the voltage at which the 
intensity of transmitted light became 90% by phase transition from a 
ferroelectric phase to a ferrielectric phase was defined as threshold 
voltage II (unit: V/.mu.m). 
Further, the time required for a change in the intensity of transmitted 
light by 90% under the application of a 8 V pulse voltage having a 
frequency of 10 Hz was defined as a response time, and the response time 
was measured. 
TABLE 4 
______________________________________ 
Threshold 
Response Measure- 
voltage 
time ment tem- 
Phase sequence I II (.mu.s) 
perature 
______________________________________ 
Ex. 16 
Cr(&lt;-10)SC.gamma.*(68)SA(87)I 
1.3 1.2 64 30.degree. C. 
Ex. 17 
Cr(&lt;-10)SC.gamma.*(55)SA(82)I 
1.2 1.1 41 30.degree. C. 
Ex. 18 
Cr(&lt;-10)SC.gamma.*(52)SA(86)I 
1.2 1.2 50 30.degree. C. 
Ex. 19 
Cr(&lt;-10)SC.gamma.*(54)SA(79)I 
1.3 1.1 45 30.degree. C. 
Cpd E1 
Cr(25)I 
Cpd E2 
Cr(37)I 
Cpd E3 
Cr(5)SA(20)I 
Lpd 3A 
Cr(34)SC.gamma.*(101)SA(103)I 
1.3 1.0 100 40.degree. C. 
______________________________________ 
In Table 4, "Cpd" stands for optically active compound and "Lpd" stands for 
liquid crystal compound. In "Phase sequence", parenthesized values show 
transition temperatures (.degree.C.), Cr is a crystal phase, SC.gamma.* is 
a ferrielectric phase, SA is a smectic A phase, and I is an isotropic 
phase.