Title of Invention	NOVEL CHOLESTERIC LIQUID CRYSTAL CONTAINING PHOTO-RESPONSIVE BUTADIENE CHROMOPHORE AND A PROCESS FOR THE PREPARATION THEREOF
Abstract	The present invention relates to a color image recording medium and information recording process making use of novel thermo- and photo-responsive butadiene-linked cholesterols possessing chiral nematic liquid crystalline phases. The rewritable full colour image recording medium consisting of a pair of substrates at least one of which is transparent, containing an intermediate photo and thermoresponsive layer. The intermediate photo- and thermo-responsive layer consists of a butadiene linked cholesterol-liquid crystalline material. Rapid cooling of the cholesteric phase formed at high temperatures to ~0 °C results in formation of glasses in which the reflected colour characteristic of the film at the temperature from which it is cooled is retained. The colour of the glasses thus formed can be tuned by controlling the temperature of the film or irradiating it with UV light in the 350 nm region prior to formation of glass by rapid cooling. Using these processes the films can be tuned to any colour. These devices can therefore be used to record highly stable full color images by controlled heating or UV irradiation of the films. Images recorded by controlling the temperature can be erased by heating the sample, while images recorded using UV irradiation can be erased by irradiating with light in 266 nm region. The device is useful therefore for recording full colour images in a reversible manner.

Title of Invention

NOVEL CHOLESTERIC LIQUID CRYSTAL CONTAINING PHOTO-RESPONSIVE BUTADIENE CHROMOPHORE AND A PROCESS FOR THE PREPARATION THEREOF

Abstract

The present invention relates to a color image recording medium and information recording process making use of novel thermo- and photo-responsive butadiene-linked cholesterols possessing chiral nematic liquid crystalline phases. The rewritable full colour image recording medium consisting of a pair of substrates at least one of which is transparent, containing an intermediate photo and thermoresponsive layer. The intermediate photo- and thermo-responsive layer consists of a butadiene linked cholesterol-liquid crystalline material. Rapid cooling of the cholesteric phase formed at high temperatures to ~0 °C results in formation of glasses in which the reflected colour characteristic of the film at the temperature from which it is cooled is retained. The colour of the glasses thus formed can be tuned by controlling the temperature of the film or irradiating it with UV light in the 350 nm region prior to formation of glass by rapid cooling. Using these processes the films can be tuned to any colour. These devices can therefore be used to record highly stable full color images by controlled heating or UV irradiation of the films. Images recorded by controlling the temperature can be erased by heating the sample, while images recorded using UV irradiation can be erased by irradiating with light in 266 nm region. The device is useful therefore for recording full colour images in a reversible manner.

Full Text	FIELD OF THE INVENTION The present invention relates to novel cholesteric liquid crystal containing photoresponsive butadiene chromophore. Particularly it relates to cholesteric liquid crystal,containing photoresponsive butadiene chromophore possessing chiral nematic liquid crystalline phases and a color image recording medium and an information recording process making use of these liquid crystals. BACKGROUND OF THE INEVNTION Design and development of organic photoresponsive materials has been an area of immense interest mainly due to their application in imaging and information recording devices (Reference may be made to US Patent No. 6,740,255; Ikeda, T. J. Mater. Chem. 2003, 13, 2037). Liquid crystals are especially useful for such applications since microscopic molecular perturbations occurring within them can be amplified to macroscopic levels, resulting in significant changes in their optical properties (Reference may be made to Demus ef a/. Handbook of Liquid Crystals , Wiley-VCH, Weinheim, 1998; Ikeda, J. Mater. Chem., 2003, 13, 2037; Chen et al. Adv. Mater. 2003, 15, 1061; Walba ef al. Science 2000, 288, 2181; Eichhorn et al. J. Am. Chem. Soc. 2002, 124, 12742; D. Demus, in Modern Topics in Liquid Crystals, ed. A. Buka, New Jersey, 1993). Cholesteric liquid crystals (CLCs) possess the inherent property of selective reflection of different wavelengths of light which arises due to a helical ordering of the molecules in the macroscopic scale (Reference may be made to F. Reinitzer, Monatsh, 1888, 9, 421; Chandrasekhar, S. Liquid crystals; 2nd ed.; Cambridge: Cambridge, 1992). The wavelength of light reflected by such materials depends on the pitch length of the helical ordering, which in turn is highly sensitive to external stimuli such as temperature, pressure and the presence of external impurities (Reference may be made to Ruslim, C. and Ichimura, K. J. Phys. Chem. B 2000, 104, 6529; Moriyama, M.; Song, S.; Matsuda, H.; Tamaoki, N. J. Mater. Chem. 2001, 11, 1003; Chen et al. Adv. Mater. 2003, 15, 1061; Mallia, V. A. and Tamaoki, N. Chem. Mater. 2003, 15, 3237; Delden ef al. Adv. Funct. Mater. 2003, 13, 319). These aspects have been subjects of innumerable studies and also make CLCs useful in a variety of display and information reading applications. The fluidity of CLCs however, has been disadvantageous in various applications, especially those pertaining to long-term storage of information. For such applications additional measures such as polymerization following the information recording process are often required (Reference may be made to Brehmer et al. Adv. Mater. 1998, 10, 17; Witte et al. Liq. Cryst. 1998, 24, 819; Tamaoki, N. Adv. Mater. 2001, 13, 1135). Furthermore, there are illustrated in U.S. Pat. Nos. 6,183,666 and 6,537,711 by Tamaoki and co-workers, the disclosure of which is totally incorporated herein by reference, cholesteric glassy liquid crystals as efficient materials for recording full colour mages in a rewriteable manner, which can also be stored over long periods of time. These systems have made use of dimesogens containing two cholesteryl groups linked with diyne and alkylchains, which form cholesteric liquid crystals which can be reversibly solidified into a glassy form which retains all the properties of selective reflections of different wavelengths of light exhibited by the cholesteric films (Reference may be made to Tamaoki, N.; Song, S; Moriyama, M.; Matsuda, H. Adv. Mater. 2000, 12, 94; Tamaoki, N.; Aoki, Y.; Moriyama, M.; Kidowaki, M. Chem. Mater. 2003, 15, 719; Mallia, V. A.; Tamaoki, N. Chew. Soc. Rev. 2004, 33, 7; Mallia, V. A.; Tamaoki, N. J. Mater. Chem. 2003, 13, 219). When these dimesogens are doped with dialkyl azobenzene derivatives possessing alkyl chains of suitable length and the films are irradiated with UV light in the 350 nm region, photoisomerization of the azobenzene derivative affect the cholesteric pitch of the CLC. This leads to a change in the colour of the film. In a recent US Patent No. 6,103,431 by Tamaoki and co-workers, the disclosure of which is totally incorporated herein by reference, these devices could be used for recording full colour images with long term stability, which could be erased by simply reheating the glass film to its cholesteric state. Although such devices could be used for recording colour images, they possess some disadvantages. The main disadvantage was the cis isomers of azobenzene are thermally unstable and revert back rapidly to the trans isomer a process, which can occur before the glassification process is completed. The second major disadvantage is that the photoresponsive material is a mixture consisting of a host liquid crystalline method and a photoisomerizable guest material, which can potentially lead to crystallization on long term storage. In a recent study we could overcome the problem of thermal stability of the photoisomers by using photoisomerizable butadiene derivatives as the guest materials (Reference may be made to Davis et al. Adv. Funct. Mater. 2004, 14, 74). These could be used to develop colour images of much better quality. However these systems also consist of a mixture of two different materials and long-term stability due to crystallization of the glass can be a major problem in such mixed systems. In this invention we describe the synthesis of a novel cholesteric liquid crystal, which consists of the photoresponsive butadiene chromophore which is covalently linked to the cholesterol derivative. This results in formation of cholesteric liquid crystals, which are inherently photoactive. Using these materials we can record full colour images, which are thermally stable. The images could also be erased by irradiating the material with short wavelength UV light (266 nm). SUMMARY OF THE INVENTION The aim of the present invention is to provide novel inherently photoactive chiral nematic liquid crystals containing a butadiene chromophore covalently connected to a cholesterol derivative using suitable linkers. These novel cholesterol derivatives possess a chiral nematic phase, which can selectively reflect different wavelength of light depending upon the temperature. Rapid cooling of their chiral nematic phases result in the formation of stable transparent glasses in which the chiral nematic superstructure is maintained. As a result these, glasses can selectively reflect different wavelength of light. The wavelength of light reflected depend upon the temperature from which are rapidly cooled. In addition thin glassy film of these materials formed between two transparent slides separated using appropriated spacers can be used for recording coloured images. This can be achieved by heating the film to its chiral nematic phase temperature until it shows the desired colour and then rapidly cooling it to form a glass. Alternatively irradiating the chiral nematic film using ultraviolet light in the 350 nm region, results in change of the pitch with corresponding change in the reflected colour. With increasing irradiation time the colour of the film can change from red to green to blue due to photoisomerization of the butadiene chromophore. Thus by controlling the time of irradiation any colour can be generated in the film. The image thus formed are of high resolution and are stable over extended periods of time (>1 year). The image can be erased by irradiating the imaged film using short wavelength ultraviolet light region. DETAILED DESCRIPTION OF THE INVENTION Brief Description of the Accompanying Drawings In the drawings accompanying specifications FIG. 1 represents the general formula of the cholesterol linked diaryl butadiene derivatives FIG. 2 shows the scheme used for synthesis of these cyano substituted cholesterol based diphenyl buatadiene derivatives FIG. 3 shows the scheme used for synthesis of dicholesterol based diphenyl butadiene derivatives FIG. 4 shows the scheme used for synthesis indanedione based cholesterol derivatives FIG. 5 represents the graph showing the effect of temperature on the reflectance spectra of formula 1 FIG. 6 represents the graphs showing changes in the reflectance spectra of formula 1 on photoirradiation using 350 nm at 105 °C FIG. 7 represents the graph showing the effect of temperature on the reflectance spectra of formula 1 The present invention has been completed based on the above findings and accordingly the present invention provides novel butadiene linked cholesterol derivatives represented by the Formula 1 shown in Figure 1 and derivatives thereof. An embodiment of the present invention is that the material process a chiral nematic phase at high temperature, which can selectively reflect different wavelength of light depending upon the derivative and the temperature. Another embodiment of the invention is that the chiral nematic phases can be rapidly cooled to form stable glasses in which the superstructure of the chiral nematic phase is retained. These glasses are capable of selectively reflecting light depending upon the temperature from which they are cooled. Yet another embodiment is that the colour which is fixed in the above manner can be erased by heating the film to its melt state. Yet another embodiment of the invention is that the wavelength of reflected light can be suitably controlled by irradiating the chiral nematic phases of varying period of time using ultraviolet light in the 350 nm. Using this method coloured image can be recorded on the film. The image thus formed can be stored over extended periods of time by rapidly cooling the material whereby it forms glasses in which the recorded image stored in a stable manner over extended period of time. Yet another embodiment of the invention is that the stored colour images can be erased by irradiating the glass film using short wavelength UV light in the wavelength range of 260 nm. The following examples are given by way of illustration. This invention is further illustrated by the following examples which should not, however, be construed to limit the scope of the present invention. Example 1 Synthesis of a compound of formula 1a 4-Hydroxy-4'-cyano-diphenylbutadiene (Structure 2) was prepared as per the Scheme in Figure 9. 4-methoxy-4'-cyano-diphenylbutadiene (Structure 1) in 84% yield was prepared according to known literature procedures. Structure 1 (1 g, 3.82 mmol) was weighed and dissolved in dry dichloromethane (35 ml) and stirred for 10 min. The reaction mixture was kept in ice for 5 min and boron tribromide (1.81 ml, 0.02 moles) was added drop wise keeping the reaction mixture at 0 °C. The solution was stirred for half an hour in ice and for 3 hours at room temperature. The mixture was cooled in ice and 50 ml of distilled water was added to it. The precipitate was filtered and dissolved in a mixture of diethylether and dichloromethane and reprecipitated by adding hexane. The precipitate was filtered and recrystallized from ethanol and dried to get 4-Hydroxy-4'-cyano-diphenylbutadiene (Structure 2, 70%). To Structure 2 (1g) dissolved in minimum amount of DMF, K2CO3 (2eq) was added and the mixture was stirred for 10 minutes. 12-Bromododecanol (1.2 eq) was added dropwise. The mixture was heated for 12 hours at 100°C, following which it was cooled and poured into ice water. The solution was neutralized with 1:1 HCI and the precipitate was filtered. The precipitate was dissolved in CHCI3 and dried over anhydrous sodium sulphate. The product was then purified by column chromatography using silica (100-200 mesh) and ethylacetate and hexane (1:1) as eluent to get Structure 3 (59%). To Structure 3 (1g, 2.3 mmol) dissolved in benzene (30 ml) was added pyridine (3 ml) and the solution was stirred well to dissolve the compound. Cholesteryl chloroformate (1.03 g, 2.3 mmol) in benzene (30 mL) was added dropwise and the mixture was refluxed for 24 hours at 80°C. Excess benzene and pyridine were distilled out under reduced pressure and the product obtained was dissolved in dichloromethane and precipitated using methanol. The product was purified by column chromatography using silca gel (100-200 mesh) and ethyl acetate and hexane (1:9) as eluent to get the corresponding cholesterol containing butadiene derivative Formula 1a (53%). Further purification was carried out using recycling HPLC in which chloroform was used as the eluent. Characterization data of Formula 1a : : IR vmax (KBr): 792, 851, 987, 1031, 1168, 1255, 1513, 1587, 1733, 2225, 2853, 2937 cm-1; 1H NMR (CDCI3, 300MHz) δ (ppm) 0.06-2.4 (m, 63H, cholesterol and aliphatic protons), 3.95 - 3.97 (t, 2H, OCH2), 4.09 -4.13 (t, 2H, OCH2), 4.47 (m, 1H, OCH), 5.57 (m, 1H, vinylic), 6.56-6.61 (d, 1H, J= 15.6 Hz), 6.68-6.73 (d, 1H J = 15.5 Hz), 6.78-6.82 (dd, 1H, J=15.4 Hz), 6.85-6.88 (d, 1H), 6.99-7.02 (dd, 1H, J = 15.1), 7.37-7.40 (d, 2H), 7.49-7.46 (d, 2H), 7.57-7.6 (d, 2H); MS (FAB+), m/z 845, Anal, calcd. for C57H81NO4. C - 81.09, H - 9.67, N.-1.66. Found C-80.96, H-9.60, N-1.59. Example 2 Synthesis of a compound of formula 1b 4-Hydroxy-4'-cyano-diphenylbutadiene (Structure 2) was prepared as per the Scheme in Figure 9 and as described earlier. To Structure 2 (1g) dissolved in minimum amount of DMF, K2CO3 (2eq) was added and the mixture was stirred for 10 minutes. 11-Bromoundecanol (1.2 eq) was added dropwise. The mixture was heated for 12 hours at 100 °C, following which it was cooled and poured into ice water. The solution was neutralized with 1:1 HCI and the precipitate was filtered. The precipitate was dissolved in CHCI3 and dried over anhydrous sodium sulphate. The product was then purified by column chromatography using silica (100-200 mesh) and ethylacetate and hexane (1:1) as eluent to get Structure 4 (59%). To Structure 4 (1g, 2.4 mmol) dissolved in benzene (50 ml) was added pyridine (3 ml) and the solution was stirred well to dissolve the compound. Cholesteryl chloroformate (1.08 g, 2.4 mmol) in benzene was added dropwise and the mixture was refluxed for 24 hours at 80°C. Excess benzene and pyridine were distilled out under reduced pressure and the product obtained was dissolved in dichloromethane and precipitated using methanol. The product was purified by column chromatography using silca gel (100-200 mesh) and ethyl acetate and hexane (1:9) as eluent to get the corresponding cholesterol containing butadiene derivative Formula 2 (53%). Further purification was carried out using recycling HPLC in which chloroform was used as the eluent. Characterization data of Formula 1b : IR vmax(KBr): 728, 801, 852, 949, 990, 1030, 1116, 1135, 1173, 1202, 1255, 1300, 1359, 1373, 1392, 1401, 1470, 1507, 1597, 1737, 2225, 2857, 2933, 3014 cm-1; 1H NMR (CDCI3, 300MHz) δ (ppm) 0.06-2.4 (m, 63H, cholesterol and aliphatic protons), 3.95 - 3.99 (t, 2H, OCH2), 4.09 - 4.13 (t, 2H, OCH2), 4.41 -4.50 (m, 1H, OCH), 5.40 (m, 1H, vinylic), 6.56-6.61 (d, 1H, J= 15.4 Hz), 6.68-6.73 (d, 1H J = 15.4 Hz), 6.76 - 6.88 (m, 3H), 6.99-7.19 (dd,1H), 7.37-7.40 (d, 2H), 7.46-7.49 (d, 2H), 7.57-7.60 (d, 2H); MS (FAB+) m/z 830 (M+, C56H79 NO4) Anal, calcd. for C56H79NO4 C- 81.01, H - 9.59, N -1.69. Found: C-80.06, H - 10.05, N - 1.83. Example 3 Synthesis of a compound of formula 1c 4-Hydroxy-4'-cyano-diphenylbutadiene (Structure 2) was prepared as per the Scheme in Figure 9 and as described earlier. To Structure 2 (1g) dissolved in minimum amount of DMF, K2CO3 (2eq) was added and the mixture was stirred for 10 minutes. 8-Bromoctanol (1.2 eq) was added dropwise. The mixture was heated for 12 hours at 100°C, following which it was cooled and poured into ice water. The solution was neutralized with 1:1 HCI and the precipitate was filtered. The precipitate was dissolved in CHCI3 and dried over anhydrous sodium sulphate. The product was then purified by column chromatography using silica (100-200 mesh) and ethylacetate and hexane (1:1) as eluent to get Structure 5 (59%). To Structure 5 (1g, 2.7 mmol) dissolved in benzene (50 ml) was added pyridine (3 ml) and the solution was stirred well to dissolve the compound. Cholesteryl chloroformate (1.2 g, 2.7 mmol) in benzene was added dropwise and the mixture was refluxed for 24 hours at 80°C. Excess benzene and pyridine were distilled out under reduced pressure and the product obtained was dissolved in dichloromethane and precipitated using methanol. The product was purified by column chromatography using silca gel (100-200 mesh) and ethyl acetate and hexane (1:9) as eluent to get the corresponding cholesterol containing butadiene derivative Formula 1c (49%). Further purification was carried out using recycling HPLC in which chloroform was used as the eluent. Characterization data of Formula 1c : IRvmax(KBr): 795, 863, 990, 1033, 1179, 1268, 1472, 1511, 1559, 1741, 2228, 2887, 2945 cm-1; 1H NMR (CDCI3, 300MHz) δ (ppm) 0.67-2.4 (m, 55H, cholesterol and aliphatic protons), 3.94-4.1 (t, 2H, OCH2), 4.09-4.14 (t, 2H, OCH2), 4.47 (m, 1H, OCH), 5.40 (m, 1H, vinylic), 6.55-6.61 (d, 1H, J=15.3 Hz), 6.68-6.73 (d, 1H J =15.3 Hz), 6.79-6.89 (m, 3H), 6.99-7.08 (dd, 1H, J=15.5), 7.37-7.4o (d, 2H), 7.46-7.49 (d, 2H), 7.57-7.60 (d, 2H); MS (FAB+) m/z 788 (M+, C53H73NO4); Anal, calcd. for C53H73NO4: C- 80.77, H - 9.34, N -1.78. Found: C-79.99, H - 9.27, N - 1.75. Example 4 Synthesis of a compound of formula 1d The 4,4'- dimethoxy diphenyl butadiene (Structure 6) was treated with KOH in triethyelene glycol to remove methoxy group to give 4,4'-dihydroxy diphenyl butadiene (Structure 7) according to literature procedures. Structure 7 (150 mg, 0.63 mmol) on treatment with hydroxyl bromo compound (351.8 mg, 126 mmol) gives the spacer linked diphenyl butadienes (Structure 9). To prepare the cholesterol linked final product, spacer-linked butadiene Structure 9 (200 mg, 0.314 mmol) is treated with cholesteryl chloroformate (281 mg, 0.628 mmol) in dry benzene (30 mL) in presence of dry pyridine (0.13 mL, 1.57 mmol). The solvent was evaporated, extracted with dichloromethane, dried over anhydrous sodium sulphate and the final purification was carried out by column chromatography using silica gel (100-200 mesh) to get colorless product Formula 1d (48%) Characterization data of Formula 1d : 1H NMR; CDCI3 (300 MHz), δ (ppm): 0.8-2.4 (m, 62, aliphatic and cholesterol protons), 3.94-3.98 (t, 2H, -OCH2), 4.09-4.13 (t, 2H, -COOCH2), 4.45-5.40 (m, 3H), 6.86-6.90(m, 2H, olephinic), 7.26-7.41 (m, 4H, aromatic). MS (MALDI-TOFF) m/z 1431 (M+, C96H150O8) Example 5 Synthesis of a compound of formula 1ea The cholesterol linked cinnamaldehyde, cholest-5-en-3-ol-(3ß) 12-(4-((E)-3-oxoprop-1-enyl)phenoxy)octyl carbonate, (100 mg, 0.145 mmol) was mixed with 1,3-indadione (21.2 mg, 0.14 mmol) in 1,4-dioxane (15 mL) as solvent and stirred at room temperature for half an hour. 2 drops of dry NEt3 was added and stirred overnight. After the reaction, the solvent was evaporated and the final purification was carried out by column chromatography using silica gel (100-200 mesh ) as the packing material and mixture (1:19) of ethyl acetate and hexane as the eluent. The final product obtained was precipitated from a mixture of dichloromethane and methanol and obtained as orange yellow powder (12%). The final product 1ea (cholest-5-en-3-ol-(3⁭)-12-(4-((E)-3-(1,3-dioxo-inden-2-ylidene)prop-1-enyl)phenoxy)octyl carbonate) obtained was precipitated from a mixture of dichloromethane and methanol and obtained as orange yellow powder. Characterization data of Formula 1ea:Yield: 12% IR vmax (KBr): 2939, 1735, 1680, 1575, 1465,1371,1257, 1163, 993, 827, 736, 528 cm-1; 1H NMR (300 MHz, CDCI3): δ 1.01-2.41 (m, 56H, cholesteric and aliphatic), 4.02 (t, 2H, methoxy), 4.12 (t, 2H, methoxy), 4.47 (m, 1H vinylic), 5.39 (m, 1H, methoxy), 6.92-6.95 (m, 1H, vinylic), 6.92-6.95 (d, 2H, aromatic), 7.34 (d, 1H, vinylic), 7.63-7.67 (m, 2H, aromatic), 7.76-7.79 (m, 2H, aromatic), 7.94-7.97 (m, 2H, aromatic), 8.29-8.38 (m, 1H, vinylic) ppm. Anal, calcd. for C54H72O6: C- 79.37, H - 8.88. Found: C-79.96, H - 8.78. Example 6 Synthesis of a compound of formula 1eb The cholesterol linked cinnamaldehyde, cholest-5-en-3-ol-(3ß) 12-(4-((E)-3-oxoprop-1-enyl)phenoxy)\dodecyl carbonate, (100 mg, 0.13 mmol) was mixed with 1,3-indadione (19 mg, 0.13 mmol) in 1,4-dioxane (15 mL) as solvent and stirred at room temperature for half an hour. 2 drops of dry NEt3 was added and stirred overnight. After the reaction, the solvent was evaporated and the final purification was carried out by column chromatography using silica gel (100-200 mesh ) as the packing material and mixture (1:19) of ethyl acetate and hexane as the eluent. The final product obtained was precipitated from a mixture of dichloromethane and methanol and obtained as orange yellow powder. The final product obtained was precipitated from a mixture of dichloromethane and methanol and obtained as orange yellow powder. Characterization data of Formula 1fa: Yield: 12 %: IR vmax (KBr): 2933, 1735, 1683, 1573, 1363, 1259, 1163, 991, 813, 736 cm-1; 1H NMR (300 MHz,CDCI3): 1.05-2.03 (m, 64H, cholesteric and aliphatic), 4.02 (t, 2H, methoxy), 4.11 (t, 2H, methoxy), 4.47 (m, 1H vinylic ), 5.4 (m, 1H, methoxy), 6.65-6.57 (m, 1H, vinylic), 6.92 -6.95 (d, 2H, aromatic), 7.34 (d, 1H, vinylic), 7.63-7.67 (m, 2H, aromatic), 7.76-7.79 (m, 2H, aromatic), 8.29-8.38 (m, 1H, vinylic) ppm. Example 7 Phase transition properties of the butadiene linked cholesterol derivatives Formula 1a on heating melts to a smectic liquid crystalline (LC) phase at 109.4 °C followed by crystallization at 112.8 °C. The material then melts into chiral nematic LC phase on further heating at 129.5 °C till complete isotropization at 188.1 °C. On cooling from isotropic state chiral nematic LC phase first formed at 176.6 °C change to smectic LC phase at 108 °C till crystallization at 73.9 °C. Formula 1b on heating melts to a smectic LC phase at 120.9 °C which then change to a chiral nematic LC phase at 145.5 °C, on further heating. The material undergoes complete isotropization at 175 °C. On cooling from isotropic state chiral nematic LC phase first formed at 162.1 °C change to smectic LC phase at 113.7 °C till crystallization at 84.9 °C. Formula 1c on heating melts to a smectic LC phase at 99.5 °C followed by crystallization at 112.8 °C. The material again melts first into a smectic LC phase at 131.9 °C followed by the formation of Twist grain-boundary A* LC phase at 149 °C till isotropization at 202.9 °C. On cooling from isotropic state chiral nematic LC phase first formed at 193.5 °C change to a Twist grain-boundary A* LC phase at 145 °C followed by the formation of a smectic LC phase at 142 °C. The material finally crystallizes at 74.9 °C. Formula 1d on heating melts to a chiral nematic LC phase at 140 °C till isotropization at 176 °C. On cooling from isotropic state chiral nematic LC phase is first formed at 170 °C, which crystallize at 128 °C. Formula 1e on heating melts to a smectic LC phase at 83 °C followed by crystallization at 110 °C. The material then melts into chiral nematic LC phase on further heating at 145 °C till complete isotropization at 169 °C. On cooling from isotropic state chiral nematic LC phase first formed at 165 °C change to smectic LC phase at 104 °C till gasification at 80 °C. Formula 1eb on heating melts to a smectic LC phase at 81 °C followed by crystallization at 97 °C. The material then melts into chiral nematic LC phase on further heating at 147 °C till complete isotropization at 150 °C. On cooling from isotropic state chiral nematic LC phase first formed at 144 °C change to smectic LC phase at 92 °C till crystallization at 72 °C. The phase transition behavior of the butadiene linked cholesterol derivatives are summarized in Table 1. Table 1 Phase transition characteristics of the butadiene linked cholesterol derivatives (Table Removed) Boundary A* G- Glass, and I - Isotropic;a As observed by DSC. Example 8 All the other derivatives show similar phase transition characteristics with their cholesteric pitch sensitive to external stimuli such as temperature, pressure and amount of cis isomers Example 9 These materials when heated to their chiral nematic phase exhibit the characteristic reflection of specific wavelength depending upon the temperature. Figures 5 & 7 shows the variation in the reflection band as a function of temperature. The wavelength shifts from long to short wavelength representative of change in colour of the film from red to green. These films can be rapidly cooled to retain any of these colours in a stable glassy state. Example 10 These materials when irradiated at smectic liquid crystalline phase using UV light in 350 nm region, isothermal phase transition to chiral nematic phase occurs. The pitch of the cholesteric helix thus formed was found to be highly sensitive to the ratio of cis/trans isomers. With increasing ratio of cis isomer cholesteric pitch shortened with corresponding hypsochromic shift in reflection band. Figure 6 shows the variation in the reflection band as a function of irradiation time. The wavelength shifts from NIR to visible region with different intervals of irradiation time. These films can be rapidly cooled to retain any of these colours in a stable glassy state. The cholesterol-linked aryl butadienes of the present invention possess satisfactory properties for imaging and industrial applications. The main advantages of these systems include: 1) Cholesterol linked aryl butadienes can be used as single pure substances. 2) The synthetic methodology is economical. 3) They are quite stable under both thermal and photochemical conditions of the experiment. 4) The smectic to chiral nematic transition can be carried out using very small energy light 1.5 mW cm-2 and the photochemical response are fast enough for imaging. 6) The thermal irreversibility of cis isomers of butadienes avoids blurring of image due to reverse isomerization. We claim 1. Novel cholesteric liquid crystal containing photosensitive butadiene chromophore of general formula 1 (Formula Removed) 2. Novel cholesteric liquid crystal containing photosensitive butadiene chromophore as claimed in claim 1 is represented by the group of the following compounds: (12-(4- ((1 E,3E)-4-(4-cyanophenyl)buta-1,3-dienyl)phenoxy)dodecyl cholest-5-en-3 -ol (3ß) carbonate) la, (11-(4-((lE,3E)-4-(4-cyanophenyl)buta-l,3- dienyl)phenoxy)undecylcholest-5-en-3-ol-(3P) carbonate) lb, (8-(4-((lE,3E)-4-(4-cyanophenyl)buta-l,3-dienyl)phenoxy)octyl cholest-5-en-3-ol-(3◘ß) carbonate) lc, (bis(12-(cholest-5-en-3-ol(3ß) carbonate)-octyl 4-phenoxy) -(lE,3E)-buta-l,3-diene) 1da, (bis(12-(cholest-5-en-3-ol(3ß) carbonate)-dodecyl 4-phenoxy) -(lE,3E)-buta-l,3-diene) ldb, cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-( 1,3-dioxo-inden-2-ylidene)prop-1 -enyl)phenoxy)octyl carbonate) lea, cholest-5-en-3-ol-(3◘-12-(4-((E)-3-(l,3-dioxo-inden-2-ylidene)prop-l-enyl)phenoxy)dodecyl carbonate leb, cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(l,3-dioxo-lH-inden-2(3H)-ylidene)prop-l-enyl)phenylamino)octyl carbonate lfa, and cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(l,3-dioxo-lH-inden-2(3H)-ylidene)prop-l-enyl)phenylamino)dodecyl carbonate lfb. 3. A process for the preparation of cholesteric liquid crystal containing photosensitive butadiene chromophore of general formula 1 (Formula Removed) the said process comprising the steps of: a) preparing 4-methoxy-4'-cyano-diphenylbutadiene (structure 1) from p- tolunitrile by the known methods, b) reacting the above said compound obtained in step(a) with boron tribromide in the molar ratio of 0.15:1- 0.2:1 in an organic solvent under stirring for a period of about 20-30 min at a temperature of 0- 4°C and further for a period of about 3-4hours at a temperature of 20- 25°C, c) cooling the above said reaction mixture to a temperature of 0-5°C, followed by adding water and filtering the resultant product and recrystallising it by known methods to obtain the compound (4- Hydroxy-4'-cyano-diphenylbutadiene) of structure 2, d) reacting 4-Hydroxy-4'-cyano-diphenylbutadiene of structure 2, with12-bromododecanol, 11-bromoundecanol or 8-bromoctanol in presence of dimethyl formamide and potassium carbonate, and heating for a period of about 12 hours at a temperature of about 100°C, then cooling the reaction mixture and neutralizing it with hydrogen chloride to obtain the precipitate followed by filtration, dissolving the above said precipitate in an organic solvent and drying by known methods, purifying the said mixture by known chromatography method to obtain the intermediate product and further dissolving the intermediate product in benzene, followed by adding pyridine to the solution, and stirring, further adding Cholesteryl chloroformate dissolved in benzene dropwise and refluxing mixture for a period of about 24 hours, at a temperature of about 80°C, distilling excess benzene and pyridine to obtain the desired produced under reduced pressure and dissolving the product obtained in an organic solvent followed by precipitating with methanol, purifying the reaction mixture obtained by known chromatographic methods to obtain the desired product of formula 1 (1a,1b or1c), OR e) reacting potassium hydroxide in triethylene glycol, at a temperature of about 200°C with 4,4'- dimethoxy diphenyl butadiene compound of structure 6 to obtain 4,4'-dihydroxy diphenyl butadiene of Structure 7,reacting the compound of structure 7 with 12-bromododecanol or 8- bromoctanol in presence of dimethyl formamide and potassium carbonate for a period of about 10-12hours, at a temperature of about 50-70°C to obtain the desired compound of structure 8 and 9, and further dissolving the compound of structure 8 and 9 in benzene, followed by adding pyridine to the solution, and stirring, further adding Cholesteryl chloroformate dissolved in benzene dropwise and refluxing mixture for a period of about 24 hours at a temperature of about 80 °C, distilling excess benzene and pyridine to under reduced pressure and dissolving the reduced mass in an organic solvent followed by precipitating with methanol, purifying the reaction mixture by known chromatographic methods to obtain the desired product of formula 1d, OR f) reacting cholesterol linked cinnamaldehyde of structure 10 with 12- bromododecanol or 8-bromoctanol in presence of 1,3-indadione and1,4-dioxane solvent followed by stirring for a period of about half an hour , and adding 2 drops of dry triethylnitrile , further stirring for about 8-10 hours, evaporating the solvent and purifiying by known chromatography methods to obtain the desired compound of formula le or 1f. 4. A process as claimed in claim 3, wherein the compound of formula 1 obtained in step (d) is represented by compounds (12-(4-((lE,3E)-4-(4-cyanophenyl)buta-l,3- dienyi)phenoxy)dodecyl cholest-5-en-3-ol(3P) carbonate) la, (11-(4-((lE,3E)-4-(4-cyanophenyl)buta-l,3-dienyl)phenoxy)undecyIcholest-5-en-3-ol-(3ß) carbonate) lb and ((8-(4-((lE,3E)-4-(4-cyanophenyl)buta-l,3-dienyl)phenoxy)octyl cholest-5-en-3-ol-(3ß) carbonate) lc. 5. A process as claimed in claim 3, wherein the compound of formula 1 obtained in step (e) is represented by the compound ((bis(12-(cholest-5-en-3-ol(3ß) carbonate)-alkoxy 14-phenoxy) -(lE,3E)-buta-l,3-diene) of formula 1d. 6. A process as claimed in claim 3, wherein the compound of formula 1d obtained in step (e) is represented by the compounds (bis(12-(cholest-5-en-3-ol(3ß) carbonate)-octyl 4-phenoxy) -(lE,3E)-buta-l,3-diene) 1da and (bis(12-(cholest-5-en-3-ol(3ß) carbonate)-dodecyl 4-phenoxy) -(lE,3E)-buta-l,3-diene) ldb. 7. A process as claimed in claim 3, wherein the compound of formula 1 obtained in step (f) is represented by compound of formula cholest-5-en-3-ol-(3p)-12-(4-((E)-3-(l,3-dioxo-inden-2-ylidene)prop-l-enyl)phenoxy)dodecyl carbonate le or 1f. 8. A process as claimed in claim 3, wherein the compound of formula le & 1f obtained in step (f) is represented by the compounds cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(1,3-dioxo-inden-2-ylidene)prop-1 -enyl)phenoxy)octyI carbonate) lea, cholest-5-en-3-ol-(3P)-12-(4-((E)-3-(l,3-dioxo-inden-2-ylidene)prop-l-enyl)phenoxy)dodecyl carbonate leb , cholest-5-en-3-ol-(3\|3)-12-(4-((E)-3-(l,3-dioxo-lH-inden-2(3H)-ylidene)prop-l-enyl)phenyl amino) octyl carbonate 1fa and cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(l,3-dioxo-lH-inden-2(3H)-ylidene)prop-l-enyl)phenylamino)dodecyl carbonate lfb. 9. A process as claimed in claim 3, wherein the organic solvent used is selected from the group consisting of carbon tetrachloride, chloroform and dichloromethane. 10. A process as claimed in claim 3, wherein the metal hydride used is selected from the group consisting of sodium, potassium, lithium and aluminium. 11. A process as claimed in claim 3, wherein the cholesteryl chloroformate used is selected from the group consisting of dodecyl cholesteryl formate, undecyl cholestryl formate and octyl cholestryl formate. 12. A process as claimed in claim 3 wherein the cholesteric liquid crystal containing photosensitive butadiene chromophore of general formula 1 obtained is represented by the group of the following compounds (12-(4-((lE,3E)-4-(4-cyanophenyl)buta- l,3-dienyI)phenoxy)dodecyl cholest-5-en-3-ol(3P) carbonate) la, (11-(4-((lE,3E)- 4-(4-cyanophenyl)buta-l,3-dieny[)phenoxy)undecylcholest-5-en-3-ol-(3ß) carbonate) 1 b, (8-(4-(( 1 E,3E)-4-(4-cyanophenyl)buta-1,3-dienyl)phenoxy)octyl cholest-5-en-3-ol-(3ß) carbonate) 1c, ((bis(12-(cholest-5-en-3-ol(3ß) carbonate)- octyl 4-phenoxy) -(lE,3E)-buta-l,3-diene) 1da, (bis(12-(cholest-5-en-3-ol(3ß) carbonate)-dodecyl 4-phenoxy) -(lE,3E)-buta-l,3-diene) ldb, cholest-5-en-3-ol-(3 ß)-12-(4-((E)-3-(1,3-dioxo-inden-2-ylidene)prop-1-enyl)phenoxy)octyl carbonate) lea, cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(l,3-dioxo-inden-2-ylidene)prop-l- enyl)phenoxy)dodecyl carbonate leb, cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(l,3-dioxo-lH-inden-2(3H)-ylidene)prop-l-enyl)phenylamino)octyl carbonate 1fa, and cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(l,3-dioxo-lH-inden-2(3H)-ylidene)prop-l-enyl)phenylamino)dodecyl carbonate 1fb. 13. A process as claimed in claim 3, wherein the cholesteric liquid crystal containing photosensitive butadiene chromophore of general formula 1 obtained is useful as a colour image recording medium and in information recording process. 14. Novel cholesteric liquid crystal containing photosensitive butadiene chromophore of general formula land a process for the preparation thereof, substantially as herein described with reference to the examples.

Full Text

FIELD OF THE INVENTION
The present invention relates to novel cholesteric liquid crystal containing photoresponsive butadiene chromophore. Particularly it relates to cholesteric liquid crystal,containing photoresponsive butadiene chromophore possessing chiral nematic liquid crystalline phases and a color image recording medium and an information recording process making use of these liquid crystals.
BACKGROUND OF THE INEVNTION
Design and development of organic photoresponsive materials has been an area of immense interest mainly due to their application in imaging and information recording devices (Reference may be made to US Patent No. 6,740,255; Ikeda, T. J. Mater. Chem. 2003, 13, 2037). Liquid crystals are especially useful for such applications since microscopic molecular perturbations occurring within them can be amplified to macroscopic levels, resulting in significant changes in their optical properties (Reference may be made to Demus ef a/. Handbook of Liquid Crystals , Wiley-VCH, Weinheim, 1998; Ikeda, J. Mater. Chem., 2003, 13, 2037; Chen et al. Adv. Mater. 2003, 15, 1061; Walba ef al. Science 2000, 288, 2181; Eichhorn et al. J. Am. Chem. Soc. 2002, 124, 12742; D. Demus, in Modern Topics in Liquid Crystals, ed. A. Buka, New Jersey, 1993). Cholesteric liquid crystals (CLCs) possess the inherent property of selective reflection of different wavelengths of light which arises due to a helical ordering of the molecules in the macroscopic scale (Reference may be made to F. Reinitzer, Monatsh, 1888, 9, 421; Chandrasekhar, S. Liquid crystals; 2nd ed.; Cambridge: Cambridge, 1992). The wavelength of light reflected by such materials depends on the pitch length of the helical ordering, which in turn is highly sensitive to external stimuli such as temperature, pressure and the presence of external impurities (Reference may be made to Ruslim, C. and Ichimura, K. J. Phys. Chem. B 2000, 104, 6529; Moriyama, M.; Song, S.; Matsuda, H.; Tamaoki, N. J. Mater. Chem. 2001, 11, 1003; Chen et al. Adv. Mater. 2003, 15, 1061; Mallia, V. A. and Tamaoki, N. Chem. Mater. 2003, 15, 3237; Delden ef al. Adv. Funct. Mater. 2003, 13, 319).
These aspects have been subjects of innumerable studies and also make CLCs useful in a variety of display and information reading applications. The fluidity of CLCs however, has been disadvantageous in various applications, especially those pertaining to long-term storage of information. For such applications additional measures such as polymerization following the information recording process are often required (Reference may be made to Brehmer et al. Adv. Mater. 1998, 10, 17; Witte et al. Liq.
Cryst. 1998, 24, 819; Tamaoki, N. Adv. Mater. 2001, 13, 1135). Furthermore, there are illustrated in U.S. Pat. Nos. 6,183,666 and 6,537,711 by Tamaoki and co-workers, the disclosure of which is totally incorporated herein by reference, cholesteric glassy liquid crystals as efficient materials for recording full colour mages in a rewriteable manner, which can also be stored over long periods of time. These systems have made use of dimesogens containing two cholesteryl groups linked with diyne and alkylchains, which form cholesteric liquid crystals which can be reversibly solidified into a glassy form which retains all the properties of selective reflections of different wavelengths of light exhibited by the cholesteric films (Reference may be made to Tamaoki, N.; Song, S; Moriyama, M.; Matsuda, H. Adv. Mater. 2000, 12, 94; Tamaoki, N.; Aoki, Y.; Moriyama, M.; Kidowaki, M. Chem. Mater. 2003, 15, 719; Mallia, V. A.; Tamaoki, N. Chew. Soc. Rev. 2004, 33, 7; Mallia, V. A.; Tamaoki, N. J. Mater. Chem. 2003, 13, 219).
When these dimesogens are doped with dialkyl azobenzene derivatives possessing alkyl chains of suitable length and the films are irradiated with UV light in the 350 nm region, photoisomerization of the azobenzene derivative affect the cholesteric pitch of the CLC. This leads to a change in the colour of the film. In a recent US Patent No. 6,103,431 by Tamaoki and co-workers, the disclosure of which is totally incorporated herein by reference, these devices could be used for recording full colour images with long term stability, which could be erased by simply reheating the glass film to its cholesteric state.
Although such devices could be used for recording colour images, they possess some disadvantages. The main disadvantage was the cis isomers of azobenzene are thermally unstable and revert back rapidly to the trans isomer a process, which can occur before the glassification process is completed. The second major disadvantage is that the photoresponsive material is a mixture consisting of a host liquid crystalline method and a photoisomerizable guest material, which can potentially lead to crystallization on long term storage. In a recent study we could overcome the problem of thermal stability of the photoisomers by using photoisomerizable butadiene derivatives as the guest materials (Reference may be made to Davis et al. Adv. Funct. Mater. 2004, 14, 74). These could be used to develop colour images of much better quality. However these systems also consist of a mixture of two different materials and long-term stability due to crystallization of the glass can be a major problem in such mixed systems.
In this invention we describe the synthesis of a novel cholesteric liquid crystal, which consists of the photoresponsive butadiene chromophore which is covalently
linked to the cholesterol derivative. This results in formation of cholesteric liquid crystals, which are inherently photoactive. Using these materials we can record full colour images, which are thermally stable. The images could also be erased by irradiating the material with short wavelength UV light (266 nm).
SUMMARY OF THE INVENTION
The aim of the present invention is to provide novel inherently photoactive chiral nematic liquid crystals containing a butadiene chromophore covalently connected to a cholesterol derivative using suitable linkers. These novel cholesterol derivatives possess a chiral nematic phase, which can selectively reflect different wavelength of light depending upon the temperature. Rapid cooling of their chiral nematic phases result in the formation of stable transparent glasses in which the chiral nematic superstructure is maintained. As a result these, glasses can selectively reflect different wavelength of light. The wavelength of light reflected depend upon the temperature from which are rapidly cooled.
In addition thin glassy film of these materials formed between two transparent slides separated using appropriated spacers can be used for recording coloured images. This can be achieved by heating the film to its chiral nematic phase temperature until it shows the desired colour and then rapidly cooling it to form a glass. Alternatively irradiating the chiral nematic film using ultraviolet light in the 350 nm region, results in change of the pitch with corresponding change in the reflected colour. With increasing irradiation time the colour of the film can change from red to green to blue due to photoisomerization of the butadiene chromophore. Thus by controlling the time of irradiation any colour can be generated in the film. The image thus formed are of high resolution and are stable over extended periods of time (>1 year). The image can be erased by irradiating the imaged film using short wavelength ultraviolet light region.
DETAILED DESCRIPTION OF THE INVENTION Brief Description of the Accompanying Drawings
In the drawings accompanying specifications
FIG. 1 represents the general formula of the cholesterol linked diaryl butadiene
derivatives
FIG. 2 shows the scheme used for synthesis of these cyano substituted
cholesterol based diphenyl buatadiene derivatives
FIG. 3 shows the scheme used for synthesis of dicholesterol based diphenyl
butadiene derivatives
FIG. 4 shows the scheme used for synthesis indanedione based cholesterol
derivatives
FIG. 5 represents the graph showing the effect of temperature on the reflectance
spectra of formula 1
FIG. 6 represents the graphs showing changes in the reflectance spectra of
formula 1 on photoirradiation using 350 nm at 105 °C
FIG. 7 represents the graph showing the effect of temperature on the reflectance
spectra of formula 1
The present invention has been completed based on the above findings and accordingly the present invention provides novel butadiene linked cholesterol derivatives represented by the Formula 1 shown in Figure 1 and derivatives thereof.
An embodiment of the present invention is that the material process a chiral nematic phase at high temperature, which can selectively reflect different wavelength of light depending upon the derivative and the temperature.
Another embodiment of the invention is that the chiral nematic phases can be rapidly cooled to form stable glasses in which the superstructure of the chiral nematic phase is retained. These glasses are capable of selectively reflecting light depending upon the temperature from which they are cooled.
Yet another embodiment is that the colour which is fixed in the above manner can be erased by heating the film to its melt state.
Yet another embodiment of the invention is that the wavelength of reflected light can be suitably controlled by irradiating the chiral nematic phases of varying period of time using ultraviolet light in the 350 nm. Using this method coloured image can be recorded on the film. The image thus formed can be stored over extended periods of time by rapidly cooling the material whereby it forms glasses in which the recorded image stored in a stable manner over extended period of time.
Yet another embodiment of the invention is that the stored colour images can be erased by irradiating the glass film using short wavelength UV light in the wavelength range of 260 nm.
The following examples are given by way of illustration.
This invention is further illustrated by the following examples which should not, however, be construed to limit the scope of the present invention.
Example 1 Synthesis of a compound of formula 1a
4-Hydroxy-4'-cyano-diphenylbutadiene (Structure 2) was prepared as per the Scheme in Figure 9. 4-methoxy-4'-cyano-diphenylbutadiene (Structure 1) in 84% yield was prepared according to known literature procedures. Structure 1 (1 g, 3.82 mmol) was weighed and dissolved in dry dichloromethane (35 ml) and stirred for 10 min. The reaction mixture was kept in ice for 5 min and boron tribromide (1.81 ml, 0.02 moles) was added drop wise keeping the reaction mixture at 0 °C. The solution was stirred for half an hour in ice and for 3 hours at room temperature. The mixture was cooled in ice and 50 ml of distilled water was added to it. The precipitate was filtered and dissolved in a mixture of diethylether and dichloromethane and reprecipitated by adding hexane. The precipitate was filtered and recrystallized from ethanol and dried to get 4-Hydroxy-4'-cyano-diphenylbutadiene (Structure 2, 70%). To Structure 2 (1g) dissolved in minimum amount of DMF, K2CO3 (2eq) was added and the mixture was stirred for 10 minutes. 12-Bromododecanol (1.2 eq) was added dropwise. The mixture was heated for 12 hours at 100°C, following which it was cooled and poured into ice water. The solution was neutralized with 1:1 HCI and the precipitate was filtered. The precipitate was dissolved in CHCI3 and dried over anhydrous sodium sulphate. The product was then purified by column chromatography using silica (100-200 mesh) and ethylacetate and hexane (1:1) as eluent to get Structure 3 (59%). To Structure 3 (1g, 2.3 mmol) dissolved in benzene (30 ml) was added pyridine (3 ml) and the solution was stirred well to dissolve the compound. Cholesteryl chloroformate (1.03 g, 2.3 mmol) in benzene (30 mL) was added dropwise and the mixture was refluxed for 24 hours at 80°C. Excess benzene and pyridine were distilled out under reduced pressure and the product obtained was dissolved in dichloromethane and precipitated using methanol. The product was purified by column chromatography using silca gel (100-200 mesh) and ethyl acetate and hexane (1:9) as eluent to get the corresponding cholesterol containing butadiene derivative Formula 1a (53%). Further purification was carried out using recycling HPLC in which chloroform was used as the eluent. Characterization data of Formula 1a : : IR vmax (KBr): 792, 851, 987, 1031, 1168, 1255, 1513, 1587, 1733, 2225, 2853, 2937 cm-1; 1H NMR (CDCI3, 300MHz) δ (ppm) 0.06-2.4 (m, 63H, cholesterol and aliphatic protons), 3.95 - 3.97 (t, 2H, OCH2), 4.09 -4.13 (t, 2H, OCH2), 4.47 (m, 1H, OCH), 5.57 (m, 1H, vinylic), 6.56-6.61 (d, 1H, J= 15.6 Hz), 6.68-6.73 (d, 1H J = 15.5 Hz), 6.78-6.82 (dd, 1H, J=15.4 Hz), 6.85-6.88 (d, 1H), 6.99-7.02 (dd, 1H, J = 15.1), 7.37-7.40 (d, 2H), 7.49-7.46 (d, 2H), 7.57-7.6 (d, 2H); MS
(FAB+), m/z 845, Anal, calcd. for C57H81NO4. C - 81.09, H - 9.67, N.-1.66. Found C-80.96, H-9.60, N-1.59.
Example 2 Synthesis of a compound of formula 1b
4-Hydroxy-4'-cyano-diphenylbutadiene (Structure 2) was prepared as per the Scheme in Figure 9 and as described earlier. To Structure 2 (1g) dissolved in minimum amount of DMF, K2CO3 (2eq) was added and the mixture was stirred for 10 minutes. 11-Bromoundecanol (1.2 eq) was added dropwise. The mixture was heated for 12 hours at 100 °C, following which it was cooled and poured into ice water. The solution was neutralized with 1:1 HCI and the precipitate was filtered. The precipitate was dissolved in CHCI3 and dried over anhydrous sodium sulphate. The product was then purified by column chromatography using silica (100-200 mesh) and ethylacetate and hexane (1:1) as eluent to get Structure 4 (59%). To Structure 4 (1g, 2.4 mmol) dissolved in benzene (50 ml) was added pyridine (3 ml) and the solution was stirred well to dissolve the compound. Cholesteryl chloroformate (1.08 g, 2.4 mmol) in benzene was added dropwise and the mixture was refluxed for 24 hours at 80°C. Excess benzene and pyridine were distilled out under reduced pressure and the product obtained was dissolved in dichloromethane and precipitated using methanol. The product was purified by column chromatography using silca gel (100-200 mesh) and ethyl acetate and hexane (1:9) as eluent to get the corresponding cholesterol containing butadiene derivative Formula 2 (53%). Further purification was carried out using recycling HPLC in which chloroform was used as the eluent. Characterization data of Formula 1b : IR vmax(KBr): 728, 801, 852, 949, 990, 1030, 1116, 1135, 1173, 1202, 1255, 1300, 1359, 1373, 1392, 1401, 1470, 1507, 1597, 1737, 2225, 2857, 2933, 3014 cm-1; 1H NMR (CDCI3, 300MHz) δ (ppm) 0.06-2.4 (m, 63H, cholesterol and aliphatic protons), 3.95 - 3.99 (t, 2H, OCH2), 4.09 - 4.13 (t, 2H, OCH2), 4.41 -4.50 (m, 1H, OCH), 5.40 (m, 1H, vinylic), 6.56-6.61 (d, 1H, J= 15.4 Hz), 6.68-6.73 (d, 1H J = 15.4 Hz), 6.76 - 6.88 (m, 3H), 6.99-7.19 (dd,1H), 7.37-7.40 (d, 2H), 7.46-7.49 (d, 2H), 7.57-7.60 (d, 2H); MS (FAB+) m/z 830 (M+, C56H79 NO4) Anal, calcd. for C56H79NO4 C- 81.01, H - 9.59, N -1.69. Found: C-80.06, H - 10.05, N - 1.83.
Example 3 Synthesis of a compound of formula 1c
4-Hydroxy-4'-cyano-diphenylbutadiene (Structure 2) was prepared as per the Scheme in Figure 9 and as described earlier. To Structure 2 (1g) dissolved in minimum amount of DMF, K2CO3 (2eq) was added and the mixture was stirred for 10 minutes. 8-Bromoctanol (1.2 eq) was added dropwise. The mixture was heated for 12 hours at 100°C, following which it was cooled and poured into ice water. The solution was neutralized with 1:1 HCI and the precipitate was filtered. The precipitate was dissolved in CHCI3 and dried over anhydrous sodium sulphate. The product was then purified by column chromatography using silica (100-200 mesh) and ethylacetate and hexane (1:1) as eluent to get Structure 5 (59%). To Structure 5 (1g, 2.7 mmol) dissolved in benzene (50 ml) was added pyridine (3 ml) and the solution was stirred well to dissolve the compound. Cholesteryl chloroformate (1.2 g, 2.7 mmol) in benzene was added dropwise and the mixture was refluxed for 24 hours at 80°C. Excess benzene and pyridine were distilled out under reduced pressure and the product obtained was dissolved in dichloromethane and precipitated using methanol. The product was purified by column chromatography using silca gel (100-200 mesh) and ethyl acetate and hexane (1:9) as eluent to get the corresponding cholesterol containing butadiene derivative Formula 1c (49%). Further purification was carried out using recycling HPLC in which chloroform was used as the eluent.
Characterization data of Formula 1c : IRvmax(KBr): 795, 863, 990, 1033, 1179, 1268, 1472, 1511, 1559, 1741, 2228, 2887, 2945 cm-1; 1H NMR (CDCI3, 300MHz) δ (ppm) 0.67-2.4 (m, 55H, cholesterol and aliphatic protons), 3.94-4.1 (t, 2H, OCH2), 4.09-4.14 (t, 2H, OCH2), 4.47 (m, 1H, OCH), 5.40 (m, 1H, vinylic), 6.55-6.61 (d, 1H, J=15.3 Hz), 6.68-6.73 (d, 1H J =15.3 Hz), 6.79-6.89 (m, 3H), 6.99-7.08 (dd, 1H, J=15.5), 7.37-7.4o (d, 2H), 7.46-7.49 (d, 2H), 7.57-7.60 (d, 2H); MS (FAB+) m/z 788 (M+, C53H73NO4); Anal, calcd. for C53H73NO4: C- 80.77, H - 9.34, N -1.78. Found: C-79.99, H - 9.27, N - 1.75.
Example 4 Synthesis of a compound of formula 1d
The 4,4'- dimethoxy diphenyl butadiene (Structure 6) was treated with KOH in triethyelene glycol to remove methoxy group to give 4,4'-dihydroxy diphenyl butadiene (Structure 7) according to literature procedures. Structure 7 (150 mg, 0.63 mmol) on treatment with hydroxyl bromo compound (351.8 mg, 126 mmol) gives the spacer linked diphenyl butadienes (Structure 9). To prepare the cholesterol linked final product,
spacer-linked butadiene Structure 9 (200 mg, 0.314 mmol) is treated with cholesteryl chloroformate (281 mg, 0.628 mmol) in dry benzene (30 mL) in presence of dry pyridine (0.13 mL, 1.57 mmol). The solvent was evaporated, extracted with dichloromethane, dried over anhydrous sodium sulphate and the final purification was carried out by column chromatography using silica gel (100-200 mesh) to get colorless product Formula 1d (48%)
Characterization data of Formula 1d : 1H NMR; CDCI3 (300 MHz), δ (ppm): 0.8-2.4 (m, 62, aliphatic and cholesterol protons), 3.94-3.98 (t, 2H, -OCH2), 4.09-4.13 (t, 2H, -COOCH2), 4.45-5.40 (m, 3H), 6.86-6.90(m, 2H, olephinic), 7.26-7.41 (m, 4H, aromatic). MS (MALDI-TOFF) m/z 1431 (M+, C96H150O8)
Example 5 Synthesis of a compound of formula 1ea
The cholesterol linked cinnamaldehyde, cholest-5-en-3-ol-(3ß) 12-(4-((E)-3-oxoprop-1-enyl)phenoxy)octyl carbonate, (100 mg, 0.145 mmol) was mixed with 1,3-indadione (21.2 mg, 0.14 mmol) in 1,4-dioxane (15 mL) as solvent and stirred at room temperature for half an hour. 2 drops of dry NEt3 was added and stirred overnight. After the reaction, the solvent was evaporated and the final purification was carried out by column chromatography using silica gel (100-200 mesh ) as the packing material and mixture (1:19) of ethyl acetate and hexane as the eluent. The final product obtained was precipitated from a mixture of dichloromethane and methanol and obtained as orange yellow powder (12%). The final product 1ea (cholest-5-en-3-ol-(3⁭)-12-(4-((E)-3-(1,3-dioxo-inden-2-ylidene)prop-1-enyl)phenoxy)octyl carbonate) obtained was precipitated from a mixture of dichloromethane and methanol and obtained as orange yellow powder.
Characterization data of Formula 1ea:Yield: 12% IR vmax (KBr): 2939, 1735, 1680, 1575, 1465,1371,1257, 1163, 993, 827, 736, 528 cm-1; 1H NMR (300 MHz, CDCI3): δ 1.01-2.41 (m, 56H, cholesteric and aliphatic), 4.02 (t, 2H, methoxy), 4.12 (t, 2H, methoxy), 4.47 (m, 1H vinylic), 5.39 (m, 1H, methoxy), 6.92-6.95 (m, 1H, vinylic), 6.92-6.95 (d, 2H, aromatic), 7.34 (d, 1H, vinylic), 7.63-7.67 (m, 2H, aromatic), 7.76-7.79 (m, 2H, aromatic), 7.94-7.97 (m, 2H, aromatic), 8.29-8.38 (m, 1H, vinylic) ppm. Anal, calcd. for C54H72O6: C- 79.37, H - 8.88. Found: C-79.96, H - 8.78.
Example 6 Synthesis of a compound of formula 1eb
The cholesterol linked cinnamaldehyde, cholest-5-en-3-ol-(3ß) 12-(4-((E)-3-oxoprop-1-enyl)phenoxy)\dodecyl carbonate, (100 mg, 0.13 mmol) was mixed with 1,3-indadione (19 mg, 0.13 mmol) in 1,4-dioxane (15 mL) as solvent and stirred at room temperature for half an hour. 2 drops of dry NEt3 was added and stirred overnight. After the reaction, the solvent was evaporated and the final purification was carried out by column chromatography using silica gel (100-200 mesh ) as the packing material and mixture (1:19) of ethyl acetate and hexane as the eluent. The final product obtained was precipitated from a mixture of dichloromethane and methanol and obtained as orange yellow powder. The final product obtained was precipitated from a mixture of dichloromethane and methanol and obtained as orange yellow powder. Characterization data of Formula 1fa: Yield: 12 %: IR vmax (KBr): 2933, 1735, 1683, 1573, 1363, 1259, 1163, 991, 813, 736 cm-1; 1H NMR (300 MHz,CDCI3): 1.05-2.03 (m, 64H, cholesteric and aliphatic), 4.02 (t, 2H, methoxy), 4.11 (t, 2H, methoxy), 4.47 (m, 1H vinylic ), 5.4 (m, 1H, methoxy), 6.65-6.57 (m, 1H, vinylic), 6.92 -6.95 (d, 2H, aromatic), 7.34 (d, 1H, vinylic), 7.63-7.67 (m, 2H, aromatic), 7.76-7.79 (m, 2H, aromatic), 8.29-8.38 (m, 1H, vinylic) ppm.
Example 7 Phase transition properties of the butadiene linked cholesterol derivatives
Formula 1a on heating melts to a smectic liquid crystalline (LC) phase at 109.4 °C followed by crystallization at 112.8 °C. The material then melts into chiral nematic LC phase on further heating at 129.5 °C till complete isotropization at 188.1 °C. On cooling from isotropic state chiral nematic LC phase first formed at 176.6 °C change to smectic LC phase at 108 °C till crystallization at 73.9 °C.
Formula 1b on heating melts to a smectic LC phase at 120.9 °C which then change to a chiral nematic LC phase at 145.5 °C, on further heating. The material undergoes complete isotropization at 175 °C. On cooling from isotropic state chiral nematic LC phase first formed at 162.1 °C change to smectic LC phase at 113.7 °C till crystallization at 84.9 °C.
Formula 1c on heating melts to a smectic LC phase at 99.5 °C followed by crystallization at 112.8 °C. The material again melts first into a smectic LC phase at 131.9 °C followed by the formation of Twist grain-boundary A* LC phase at 149 °C till isotropization at 202.9 °C. On cooling from isotropic state chiral nematic LC phase first
formed at 193.5 °C change to a Twist grain-boundary A* LC phase at 145 °C followed by the formation of a smectic LC phase at 142 °C. The material finally crystallizes at 74.9 °C.
Formula 1d on heating melts to a chiral nematic LC phase at 140 °C till isotropization at 176 °C. On cooling from isotropic state chiral nematic LC phase is first formed at 170 °C, which crystallize at 128 °C.
Formula 1e on heating melts to a smectic LC phase at 83 °C followed by crystallization at 110 °C. The material then melts into chiral nematic LC phase on further heating at 145 °C till complete isotropization at 169 °C. On cooling from isotropic state chiral nematic LC phase first formed at 165 °C change to smectic LC phase at 104 °C till gasification at 80 °C.
Formula 1eb on heating melts to a smectic LC phase at 81 °C followed by crystallization at 97 °C. The material then melts into chiral nematic LC phase on further heating at 147 °C till complete isotropization at 150 °C. On cooling from isotropic state chiral nematic LC phase first formed at 144 °C change to smectic LC phase at 92 °C till crystallization at 72 °C.
The phase transition behavior of the butadiene linked cholesterol derivatives are summarized in Table 1.
Table 1 Phase transition characteristics of the butadiene linked cholesterol derivatives
(Table Removed)
Boundary A* G- Glass, and I - Isotropic;a As observed by DSC.
Example 8
All the other derivatives show similar phase transition characteristics with their cholesteric pitch sensitive to external stimuli such as temperature, pressure and amount of cis isomers
Example 9
These materials when heated to their chiral nematic phase exhibit the characteristic reflection of specific wavelength depending upon the temperature. Figures 5 & 7 shows the variation in the reflection band as a function of temperature. The wavelength shifts from long to short wavelength representative of change in colour of the film from red to green. These films can be rapidly cooled to retain any of these colours in a stable glassy state.
Example 10
These materials when irradiated at smectic liquid crystalline phase using UV light in 350 nm region, isothermal phase transition to chiral nematic phase occurs. The pitch of the cholesteric helix thus formed was found to be highly sensitive to the ratio of cis/trans isomers. With increasing ratio of cis isomer cholesteric pitch shortened with corresponding hypsochromic shift in reflection band. Figure 6 shows the variation in the reflection band as a function of irradiation time. The wavelength shifts from NIR to visible region with different intervals of irradiation time. These films can be rapidly cooled to retain any of these colours in a stable glassy state.
The cholesterol-linked aryl butadienes of the present invention possess satisfactory properties for imaging and industrial applications. The main advantages of these systems include:
1) Cholesterol linked aryl butadienes can be used as single pure substances.
2) The synthetic methodology is economical.
3) They are quite stable under both thermal and photochemical conditions of the experiment.
4) The smectic to chiral nematic transition can be carried out using very small energy light
1.5 mW cm-2 and the photochemical response are fast enough for imaging. 6) The thermal irreversibility of cis isomers of butadienes avoids blurring of image due to reverse isomerization.

We claim
1. Novel cholesteric liquid crystal containing photosensitive butadiene chromophore of general formula 1
(Formula Removed)
2. Novel cholesteric liquid crystal containing photosensitive butadiene chromophore
as claimed in claim 1 is represented by the group of the following compounds: (12-(4-
((1 E,3E)-4-(4-cyanophenyl)buta-1,3-dienyl)phenoxy)dodecyl cholest-5-en-3 -ol (3ß)
carbonate) la, (11-(4-((lE,3E)-4-(4-cyanophenyl)buta-l,3-
dienyl)phenoxy)undecylcholest-5-en-3-ol-(3P) carbonate) lb, (8-(4-((lE,3E)-4-(4-cyanophenyl)buta-l,3-dienyl)phenoxy)octyl cholest-5-en-3-ol-(3◘ß) carbonate) lc, (bis(12-(cholest-5-en-3-ol(3ß) carbonate)-octyl 4-phenoxy) -(lE,3E)-buta-l,3-diene) 1da, (bis(12-(cholest-5-en-3-ol(3ß) carbonate)-dodecyl 4-phenoxy) -(lE,3E)-buta-l,3-diene) ldb, cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-( 1,3-dioxo-inden-2-ylidene)prop-1 -enyl)phenoxy)octyl carbonate) lea, cholest-5-en-3-ol-(3◘-12-(4-((E)-3-(l,3-dioxo-inden-2-ylidene)prop-l-enyl)phenoxy)dodecyl carbonate leb, cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(l,3-dioxo-lH-inden-2(3H)-ylidene)prop-l-enyl)phenylamino)octyl carbonate lfa, and cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(l,3-dioxo-lH-inden-2(3H)-ylidene)prop-l-enyl)phenylamino)dodecyl carbonate lfb.
3. A process for the preparation of cholesteric liquid crystal containing photosensitive butadiene chromophore of general formula 1
(Formula Removed)
the said process comprising the steps of:
a) preparing 4-methoxy-4'-cyano-diphenylbutadiene (structure 1) from p-
tolunitrile by the known methods,
b) reacting the above said compound obtained in step(a) with boron
tribromide in the molar ratio of 0.15:1- 0.2:1 in an organic solvent
under stirring for a period of about 20-30 min at a temperature of 0-
4°C and further for a period of about 3-4hours at a temperature of 20-
25°C,
c) cooling the above said reaction mixture to a temperature of 0-5°C,
followed by adding water and filtering the resultant product and
recrystallising it by known methods to obtain the compound (4-
Hydroxy-4'-cyano-diphenylbutadiene) of structure 2,
d) reacting 4-Hydroxy-4'-cyano-diphenylbutadiene of structure 2,
with12-bromododecanol, 11-bromoundecanol or 8-bromoctanol in
presence of dimethyl formamide and potassium carbonate, and heating
for a period of about 12 hours at a temperature of about 100°C, then
cooling the reaction mixture and neutralizing it with hydrogen chloride
to obtain the precipitate followed by filtration, dissolving the above
said precipitate in an organic solvent and drying by known methods,
purifying the said mixture by known chromatography method to obtain
the intermediate product and further dissolving the intermediate
product in benzene, followed by adding pyridine to the solution, and
stirring, further adding Cholesteryl chloroformate dissolved in benzene
dropwise and refluxing mixture for a period of about 24 hours, at a
temperature of about 80°C, distilling excess benzene and pyridine to
obtain the desired produced under reduced pressure and dissolving the
product obtained in an organic solvent followed by precipitating with methanol, purifying the reaction mixture obtained by known chromatographic methods to obtain the desired product of formula 1 (1a,1b or1c), OR
e) reacting potassium hydroxide in triethylene glycol, at a temperature of
about 200°C with 4,4'- dimethoxy diphenyl butadiene compound of
structure 6 to obtain 4,4'-dihydroxy diphenyl butadiene of Structure
7,reacting the compound of structure 7 with 12-bromododecanol or 8-
bromoctanol in presence of dimethyl formamide and potassium
carbonate for a period of about 10-12hours, at a temperature of about
50-70°C to obtain the desired compound of structure 8 and 9, and
further dissolving the compound of structure 8 and 9 in benzene,
followed by adding pyridine to the solution, and stirring, further
adding Cholesteryl chloroformate dissolved in benzene dropwise and
refluxing mixture for a period of about 24 hours at a temperature of
about 80 °C, distilling excess benzene and pyridine to under reduced
pressure and dissolving the reduced mass in an organic solvent
followed by precipitating with methanol, purifying the reaction
mixture by known chromatographic methods to obtain the desired
product of formula 1d,
OR
f) reacting cholesterol linked cinnamaldehyde of structure 10 with 12-
bromododecanol or 8-bromoctanol in presence of 1,3-indadione
and1,4-dioxane solvent followed by stirring for a period of about half
an hour , and adding 2 drops of dry triethylnitrile , further stirring for
about 8-10 hours, evaporating the solvent and purifiying by known
chromatography methods to obtain the desired compound of formula
le or 1f.
4. A process as claimed in claim 3, wherein the compound of formula 1 obtained in step (d) is represented by compounds (12-(4-((lE,3E)-4-(4-cyanophenyl)buta-l,3-
dienyi)phenoxy)dodecyl cholest-5-en-3-ol(3P) carbonate) la, (11-(4-((lE,3E)-4-(4-cyanophenyl)buta-l,3-dienyl)phenoxy)undecyIcholest-5-en-3-ol-(3ß) carbonate) lb and ((8-(4-((lE,3E)-4-(4-cyanophenyl)buta-l,3-dienyl)phenoxy)octyl cholest-5-en-3-ol-(3ß) carbonate) lc.
5. A process as claimed in claim 3, wherein the compound of formula 1 obtained in step (e) is represented by the compound ((bis(12-(cholest-5-en-3-ol(3ß) carbonate)-alkoxy 14-phenoxy) -(lE,3E)-buta-l,3-diene) of formula 1d.
6. A process as claimed in claim 3, wherein the compound of formula 1d obtained in step (e) is represented by the compounds (bis(12-(cholest-5-en-3-ol(3ß) carbonate)-octyl 4-phenoxy) -(lE,3E)-buta-l,3-diene) 1da and (bis(12-(cholest-5-en-3-ol(3ß) carbonate)-dodecyl 4-phenoxy) -(lE,3E)-buta-l,3-diene) ldb.
7. A process as claimed in claim 3, wherein the compound of formula 1 obtained in step (f) is represented by compound of formula cholest-5-en-3-ol-(3p)-12-(4-((E)-3-(l,3-dioxo-inden-2-ylidene)prop-l-enyl)phenoxy)dodecyl carbonate le or 1f.
8. A process as claimed in claim 3, wherein the compound of formula le & 1f obtained in step (f) is represented by the compounds cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(1,3-dioxo-inden-2-ylidene)prop-1 -enyl)phenoxy)octyI carbonate) lea, cholest-5-en-3-ol-(3P)-12-(4-((E)-3-(l,3-dioxo-inden-2-ylidene)prop-l-enyl)phenoxy)dodecyl carbonate leb , cholest-5-en-3-ol-(3|3)-12-(4-((E)-3-(l,3-dioxo-lH-inden-2(3H)-ylidene)prop-l-enyl)phenyl amino) octyl carbonate 1fa and cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(l,3-dioxo-lH-inden-2(3H)-ylidene)prop-l-enyl)phenylamino)dodecyl carbonate lfb.
9. A process as claimed in claim 3, wherein the organic solvent used is selected from the group consisting of carbon tetrachloride, chloroform and dichloromethane.
10. A process as claimed in claim 3, wherein the metal hydride used is selected from the group consisting of sodium, potassium, lithium and aluminium.
11. A process as claimed in claim 3, wherein the cholesteryl chloroformate used is selected from the group consisting of dodecyl cholesteryl formate, undecyl cholestryl formate and octyl cholestryl formate.
12. A process as claimed in claim 3 wherein the cholesteric liquid crystal containing photosensitive butadiene chromophore of general formula 1 obtained is represented
by the group of the following compounds (12-(4-((lE,3E)-4-(4-cyanophenyl)buta-
l,3-dienyI)phenoxy)dodecyl cholest-5-en-3-ol(3P) carbonate) la, (11-(4-((lE,3E)-
4-(4-cyanophenyl)buta-l,3-dieny[)phenoxy)undecylcholest-5-en-3-ol-(3ß)
carbonate) 1 b, (8-(4-(( 1 E,3E)-4-(4-cyanophenyl)buta-1,3-dienyl)phenoxy)octyl
cholest-5-en-3-ol-(3ß) carbonate) 1c, ((bis(12-(cholest-5-en-3-ol(3ß) carbonate)-
octyl 4-phenoxy) -(lE,3E)-buta-l,3-diene) 1da, (bis(12-(cholest-5-en-3-ol(3ß)
carbonate)-dodecyl 4-phenoxy) -(lE,3E)-buta-l,3-diene) ldb, cholest-5-en-3-ol-(3
ß)-12-(4-((E)-3-(1,3-dioxo-inden-2-ylidene)prop-1-enyl)phenoxy)octyl carbonate)
lea, cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(l,3-dioxo-inden-2-ylidene)prop-l-
enyl)phenoxy)dodecyl carbonate leb, cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(l,3-dioxo-lH-inden-2(3H)-ylidene)prop-l-enyl)phenylamino)octyl carbonate 1fa, and cholest-5-en-3-ol-(3ß)-12-(4-((E)-3-(l,3-dioxo-lH-inden-2(3H)-ylidene)prop-l-enyl)phenylamino)dodecyl carbonate 1fb.
13. A process as claimed in claim 3, wherein the cholesteric liquid crystal containing
photosensitive butadiene chromophore of general formula 1 obtained is useful as a
colour image recording medium and in information recording process.
14. Novel cholesteric liquid crystal containing photosensitive butadiene chromophore of general formula land a process for the preparation thereof, substantially as herein described with reference to the examples.

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Patent Number

254577

Indian Patent Application Number

1221/DEL/2006

PG Journal Number

47/2012

Publication Date

23-Nov-2012

Grant Date

21-Nov-2012

Date of Filing

18-May-2006

Name of Patentee

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH

Applicant Address

ANUSANDHAN BHAWAN, RAFI MARG, NEW DELHI-110001, INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	SURESH DAS, SHIBU ABRAHAM	INSTT (AIST), CENTRAL 5,1-1-1 HIGASHI, TSUKUBA, IBARAKI 305-8565, JAPAN
2	NOBUYUKI TAMAOKI	INSTT (AIST), CENTRAL 5,1-1-1 HIGASHI, TSUKUBA, IBARAKI 305-8565, JAPAN
3	VISWANTH AJAYA MALLIA	INSTT (AIST), CENTRAL 5,1-1-1 HIGASHI, TSUKUBA, IBARAKI 305-8565, JAPAN

PCT International Classification Number

G02F 1/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA