Near-infrared light-emitting disc-shaped liquid crystal compound as well as preparation method and application thereof

Abstract

The invention discloses a near-infrared light-emitting disc-shaped liquid crystal compound as well as a preparation method and application thereof, and the compound has the structural self-healing property and near-infrared light-emitting property of liquid crystal molecules and can be applied to the field of anti-counterfeiting display. After a substrate is coated with the compound, under the irradiation of external light, the compound can be detected to emit light only under a near-infrared laser sensor, so that the anti-counterfeiting complexity is remarkably increased. In addition, the compound also has light modulation capability, can change the luminescence characteristic under the action of an external field, and further improves the anti-counterfeiting effect. Meanwhile, the preparation method is simple and efficient, the used raw materials are low in price and easy to obtain, reaction conditions are mild and safe, the product purification process is simple and convenient, and the method is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of functional materials, and more specifically, to a near-infrared light-emitting discotic liquid crystal compound, a preparation method thereof, and an application thereof. Background Art

[0002] Discotic liquid crystal molecules are a type of liquid crystal material with unique optical properties. Due to their unique self-assembly behavior and good optical tunability, they have been widely studied and applied in anti-counterfeiting display technologies. Discotic liquid crystal molecules have a unique layered structure and optical anisotropy, which enable them to produce different optical effects under different lighting conditions. In addition, some discotic liquid crystal materials are sensitive to temperature changes and can be designed to display different colors or patterns at specific temperatures. Discotic liquid crystal molecules generally have good chemical and physical stability, which enables them to maintain their optical properties under various environmental conditions. This stability ensures the long-term effectiveness of anti-counterfeiting labels and has very important commercial application prospects in the anti-counterfeiting field.

[0003] Near-infrared light-emitting materials show good application potential in the field of anti-counterfeiting display. Such materials possess some unique optical and chemical properties. They emit light outside the visible light range, making the patterns on product labels or bills invisible under ordinary light and detectable only under specific near-infrared laser sensors, which increases the complexity of anti-counterfeiting. In addition, near-infrared light-emitting discotic liquid crystal materials have the ability of light modulation and can change their luminescence characteristics according to external stimuli, thereby realizing the display of dynamic patterns. The response time of liquid crystals is relatively fast, enabling fast display and hiding response modes and improving the effectiveness of anti-counterfeiting display. However, there are still some defects and challenges in the practical application of such materials, such as low luminescence efficiency, insufficient liquid crystal phase stability, difficulties in synthesis and purification, environmental sensitivity, poor processing compatibility, etc.

[0004] In view of this, designing and developing discotic liquid crystal materials with the characteristics of structural self-healing of liquid crystal molecules and near-infrared light emission has important practical significance for anti-counterfeiting display. However, there are relatively few research reports on near-infrared light-emitting discotic liquid crystals at present. Summary of the Invention

[0005] The object of the present invention is to overcome the above-mentioned defects existing in the prior art, and to provide a near-infrared light-emitting discotic liquid crystal compound, a preparation method thereof, and an application thereof. This compound combines the tunability of the liquid crystal molecular structure and the photoluminescence characteristics of fluorescent molecules. At the same time, its emission range is in the near-infrared region, and the change of the photoluminescence intensity in the near-infrared region is realized through temperature tuning, which can be applied to the field of anti-counterfeiting display; moreover, the synthesis method of the discotic liquid crystal organic compound of the present invention is simple, has a high yield, and is convenient for purification, which is beneficial to industrial production.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A near-infrared light-emitting discotic liquid crystal compound, the structural formula of the compound is as follows:

[0008]

[0009] The present invention also discloses a preparation method of the near-infrared light-emitting discotic liquid crystal compound as described above, comprising the following steps:

[0010] S1. Under the condition of nitrogen protection, sodium is dissolved in a solvent and reacted at 60 - 130 °C for 1 - 24 h. Subsequently, tris(dodecyl)terphenylcarbonitrile is added to the flask, and a solution of diisopropyl succinate is added dropwise by syringe within 2 - 48 h, and refluxed for 2 - 48 h, then acetic acid is injected for acidification for 1 - 5 h. After the reaction is completed, it is successively subjected to extraction, separation, and purification treatments to obtain Compound 1;

[0011] S2. Under the condition of nitrogen protection, Compound 1 and Compound 2 are dissolved in a solvent, then phosphorus oxychloride is added, and the reaction is continued at 20 - 160 °C for 1 - 72 h. After successively undergoing extraction, separation, and purification treatments, Compound 3 is obtained;

[0012] S3. At room temperature, the Compound 3 is dissolved in a solvent, and N,N - diisopropylethylamine and an organic weak base such as triethylamine are added dropwise. After reacting for 1 - 60 min, a dichloromethane solution containing 2 - chloro - 1,3,2 - benzenediol borate is added dropwise for reaction. After successively undergoing extraction, separation, and purification treatments, the near-infrared light-emitting discotic liquid crystal compound is obtained.

[0013] Optionally, the chemical reaction formula of the near-infrared light-emitting discotic liquid crystal compound of the present invention is as follows:

[0014]

[0015] Optionally, in S1, the molar feeding ratio of sodium, solvent, tris(dodecyl)terphenylcarbonitrile, diisopropyl succinate, and acetic acid is 1:(1.0 - 4):(1 - 10):(0.1 - 20):(1 - 20).

[0016] Optionally, in S1, the operation steps of extraction, separation, and purification specifically include: after the reaction is completed, extraction is carried out with dichloromethane, the organic layer is dried with anhydrous sodium sulfate, and finally the organic solvent is removed by vacuum distillation, and the crude product is separated by a chromatography column to obtain Compound 1.

[0017] Optionally, in S2, the molar feeding ratio of Compound 1, Compound 2, and phosphorus oxychloride is 1:(1.05 - 1.1):(4 - 6).

[0018] Optionally, in the step S2, the operation steps of extraction, separation, and purification specifically include: after the reaction is completed, slowly add saturated sodium carbonate solution to the obtained reaction solution until the pH of the solution is neutral, extract with dichloromethane, dry the organic layer with anhydrous sodium sulfate, and finally perform vacuum distillation to remove the organic solvent. The crude product is separated by a chromatography column to obtain the compound 3.

[0019] Optionally, in the step S3, the molar ratio of the compound 3, the organic weak base, and 2-chloro-1,3,2-benzenediol borate is 1:(6-8):(10-12).

[0020] Optionally, the organic weak base includes N,N-diisopropylethylamine or triethylamine.

[0021] Optionally, in the step S3, the operation steps of extraction, separation, and purification specifically include: after the reaction is completed, slowly add glacial acetic acid to the obtained reaction solution until the pH of the solution is 2-7, then extract with dichloromethane, combine the organic layers and dry with anhydrous sodium sulfate, and finally perform vacuum distillation to remove the organic solvent. The crude product is purified by column chromatography to obtain the near-infrared luminescent disc-shaped liquid crystal compound.

[0022] The present invention also discloses an application of the near-infrared luminescent disc-shaped liquid crystal compound as described above in anti-counterfeiting display.

[0023] Optionally, the method of the application includes: coating a near-infrared luminescent disc-shaped liquid crystal compound with a concentration of 0.001 mg / mL to 100 mg / mL on a substrate, and then regulating its photoluminescence intensity by an external field.

[0024] Optionally, the external field includes an external heating field or an external electric field.

[0025] Optionally, the coating method includes one of coating, printing, spraying, evaporation, and sol-gel method; the substrate includes one of paper, plastic, metal, glass, polymer, and ceramic.

[0026] Optionally, in the step S1, the solvent includes at least one of ethanol, tert-amyl alcohol, and pentanol.

[0027] Optionally, in the step S2, the solvent includes at least one of toluene, chlorobenzene, tetrahydrofuran, chloroform, and dichloromethane.

[0028] Optionally, in the step S3, the solvent includes at least one of toluene, chlorobenzene, tetrahydrofuran, chloroform, and dichloromethane.

[0029] Implementing the embodiments of the present invention will have the following beneficial effects:

[0030] 1. The present invention designs a near-infrared emitting discotic liquid crystal compound. This compound combines the structural self-healing property of liquid crystal molecules and the near-infrared emitting characteristic, and can be applied to the field of anti-counterfeiting display. After being coated on a substrate, under the irradiation of external light, its luminescence can only be detected by a near-infrared laser sensor, thus significantly increasing the complexity of anti-counterfeiting. In addition, this compound also has the ability of light modulation, and can change the luminescence characteristics under the action of an external field, further enhancing the anti-counterfeiting effect.

[0031] 2. The preparation method disclosed by the present invention is simple and efficient. The raw materials used are inexpensive and easy to obtain, the reaction conditions are mild and safe, and the product purification process is simple, which is suitable for industrial production.

[0032] 3. The near-infrared emitting discotic liquid crystal compound provided by the present invention has a significant anti-counterfeiting effect, broad application prospects, and can bring good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is the 1H NMR spectrum of compound PPCy-R in Example 2 of the present invention.

[0034] Figure 2 is the POM diagram of compound PPCy-R in the liquid crystal state in Example 2 of the present invention.

[0035] Figure 3 is the DSC diagram of compound PPCy-R in Example 2 of the present invention.

[0036] Figure 4 is the UV-Vis absorption spectrum diagram of compound PPCy-R in the thin film and solution states in Example 2 of the present invention.

[0037] Figure 5 is the photoluminescence spectrum diagram of compound PPCy-R in the thin film and solution states in Example 2 of the present invention.

[0038] Figure 6 is the infrared fluorescence photograph of the anti-counterfeiting label prepared from the compound PPCy-Br obtained in Example 3.

[0039] Figure 7 is the photoluminescence spectrum diagram of the thin films spin-coated with different concentrations of the compound PPCy-Br obtained in Example 3 of the present invention.

[0040] Figure 8 is the variable-temperature photoluminescence spectrum diagram of the compound PPCy-Br obtained in Example 3 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0041] The following is a further description of the present invention in conjunction with specific embodiments, but the present invention is not limited in any way.

[0042] The chemical reaction equations involved in the embodiments of the present invention are as follows:

[0043]

[0044] The following are specific examples

[0045] Example 1

[0046] The preparation method of Compound 3 in this example includes the following steps:

[0047] S1. Under nitrogen protection, 4.80 mmol of sodium was dissolved in 40 mL of tert-amyl alcohol and reacted at 100 °C for 1 h. Then, tris(dodecyloxy)benzene biphenylcarbonitrile was added to the flask. 1 mmol of diisopropyl succinate was added by syringe within 5 h. After refluxing for 24 h, 10 mL of acetic acid was injected and acidified for 1 h. After the reaction ended, it was washed with water three times, and the organic phase was dried with anhydrous MgSO4. The solvent was removed under reduced pressure to obtain 1.00 g of a red solid (Compound 1, yield about 65%).

[0048] S2. Under nitrogen protection, 0.77 mmol of tris(dodecyloxy)phenyl borate, 0.33 mmol of 2-(5-bromopyridin-2-yl)acetonitrile, 1.67 mmol of KOAc, and 0.05 mmol of PdCl2(PPh3)2 were dissolved in 10 mL of 1,4-dioxane and reacted at 90 °C for 24 h. After the reaction solution was washed with water three times, the organic phase was dried with anhydrous MgSO4, and the solvent was removed under reduced pressure to obtain a red solid (Compound 2, yield about 60 - 80%).

[0049] S2. Under nitrogen protection, 0.65 mmol of Compound 1 and 0.72 mmol of Compound 2 were dissolved in 10 mL of anhydrous toluene. 0.6058 g of phosphorus oxychloride was added dropwise to the above reaction system at 110 °C and reacted for 48 h. After the reaction ended, deionized water was slowly dropped in to remove the remaining phosphorus oxychloride. The organic phase was washed with saturated brine, extracted with dichloromethane, dried with anhydrous sodium sulfate, and finally the organic solvent was removed by distillation under reduced pressure to obtain a green solid (Compound 3-Ph, yield 60 - 65%).

[0050] Example 2

[0051] The preparation method of Compound 3 in this example includes the following steps:

[0052] S1. Under nitrogen protection, dissolve 4.80 mmol of sodium in 40 mL of tert-amyl alcohol and react at 100 °C for 1 h. Then, add the compound tris(dodecyl)benzonitrile to the flask. Add 1 mmol of diisopropyl succinate dropwise with a syringe within 5 h. After refluxing for 24 h, inject 10 mL of acetic acid and acidify for 1 h. After the reaction is completed, wash three times with water, dry the organic phase with anhydrous MgSO4, and remove the solvent under reduced pressure. Obtain 1.00 g of a red solid (Compound 1, yield approximately 65%).

[0053] S2. Under nitrogen protection, dissolve 7.41 mmol of potassium cyanide and 0.079 mmol of potassium iodide together with 3.70 mmol of 5-bromo-2-(chloromethyl)pyridine in a mixed solution of 6 mL of ethanol and 2 mL of water. Stir the mixture at 80 °C for 6 h, then dilute with dichloromethane and wash with a saturated sodium bicarbonate solution. Dry the organic phase over anhydrous MgSO4, filter, and evaporate the solvent under reduced pressure. Obtain 0.498 g of a solid (Compound 2, yield 60 - 70%).

[0054] S2. Under nitrogen protection, dissolve 0.65 mmol of Compound 1 and 0.72 mmol of Compound 2 in 10 mL of anhydrous toluene. Dropwise add 0.6058 g of phosphorus oxychloride to the above reaction system at 110 °C and react for 48 h. After the reaction is completed, slowly add deionized water dropwise to remove the remaining phosphorus oxychloride in the reaction. Wash the organic phase with saturated brine, extract with dichloromethane, dry with anhydrous sodium sulfate, and finally distill off the organic solvent under reduced pressure to obtain a green solid (Compound 3-Br, yield 60 - 65%).

[0055] The NMR data of Compound 3-Ph are as follows: 1 H NMR(500MHz,CDCl3)δ=8.59(s,2H),7.86(d,2H),7.77(t,8H),7.68(d,2H),6.84(s,4H),6.70(s,4H),4.01(m,12H),1.80–1.24(m,120H),0.92–0.81(m,36H).

[0056] The NMR data of Compound 3-Br are as follows: 1 H NMR(400MHz,CDCl3)δ=8.55(d,2H),7.78(d,4H),7.72(d,4H),7.71(d,4H),7.54(m,2H),6.87(s,2H),4.04(m,12H),1.82–1.23(m,120H),0.89(m,18H).

[0057] Example 3

[0058] Based on Example 1, the preparation method of the near-infrared luminescent discotic liquid crystal compound PPCy-Ph of this example includes the following steps:

[0059] At room temperature, dissolve 1 g of compound 3-Ph in 30 mL of dichloromethane, and dropwise add 0.3628 g, 2.8 mmol of N,N-diisopropylethylamine. After reacting for 10 min, dropwise add 4.8 mL, 1 M dichloromethane solution of 2-chloro-1,3,2-benzenediol borate to the reaction system. React until TLC detects that the raw materials have completely reacted. After the reaction is completed, slowly add glacial acetic acid to the reaction solution until the solution pH is acidic, then extract with dichloromethane, combine the organic layers and dry with anhydrous sodium sulfate. Finally, distill off the organic solvent under reduced pressure, and the crude product is purified by column chromatography (eluent dichloromethane) to obtain the green compound PPCy-Ph (yield 90%).

[0060] Example 4

[0061] Based on Example 2, the preparation method of the near-infrared luminescent discotic liquid crystal compound PPCy-Br of this example includes the following steps:

[0062] At room temperature, dissolve 1 g of compound 3-Br in 30 mL of dichloromethane, and dropwise add 0.3628 g, 2.8 mmol of N,N-diisopropylethylamine. After reacting for 10 min, dropwise add 4.8 mL, 1 M dichloromethane solution of 2-chloro-1,3,2-benzenediol borate to the reaction system. React until TLC detects that the raw materials have completely reacted. After the reaction is completed, slowly add glacial acetic acid to the reaction solution until the solution pH is acidic, then extract with dichloromethane, combine the organic layers and dry with anhydrous sodium sulfate. Finally, distill off the organic solvent under reduced pressure, and the crude product is purified by column chromatography (eluent dichloromethane) to obtain the green compound PPCy-Br (yield 90%).

[0063] The NMR data of PPCy-Ph is as follows: 1 H NMR(400MHz,CDCl3)δ=8.09(d,2H),7.96(m,2H),7.62(d,2H),7.44(d,4H),7.23(d,4H),6.64(s,4H),6.52(m,4H),6.45–6.41(m,4H),6.41(s4H),4.04(m,12H),3.89(t,4H),3.78(t,8H),1.86–1.22(m,240H),0.93–0.83(m,36H).

[0064] The NMR data of PPCy-Br is as follows: 11H NMR (400 MHz, CDCl3) δ = 7.94 (d, 2H), 7.85 (m, 2H), 7.48 (d, 2H), 7.35 (d, 4H), 7.19 (d, 4H), 6.64 (s, 4H), 6.55 (m, 4H), 6.40 (m, 4H), 4.07 (t, 4H), 4.00 (t, 4H), 1.87 (d, 4H), 1.87–1.74 (m, 8H), 1.55 (s, 4H), 1.52 - 1.27 (m, 120H), 0.89 (m, J = 18H).

[0065] Test Example

[0066] The compounds prepared in Example 3 and Example 4 were further analyzed as Figures 1-7 shown.

[0067] From Figure 1 the 1H NMR spectra, it can be seen that the compounds PPCy-Ph and PPCy-Br synthesized by the preparation method have high purity.

[0068] From Figure 2 it can be seen that typical columnar phase liquid crystal textures were observed for both PPCy-Ph (left figure) and PPCy-Br (right figure) during the heating process, and it was found that the above textures have a certain fluidity by pressing.

[0069] From Figure 3 it can be seen that two phase transition temperatures appeared for both PPCy-Ph and PPCy-Br. This indicates that both PPCy-Ph and PPCy-Br can form columnar phase liquid crystals.

[0070] From Figure 4 it can be seen that PPCy-Ph and PPCy-Br show similar absorption peaks in the solution and thin film states. The maximum absorption peaks of the solution of PPCy-Ph are 669 nm and 738 nm respectively; the maximum absorption peaks of its thin film are 680 nm and 750 nm respectively. The maximum absorption peaks of the solution of PPCy-Br are 669 nm and 714 nm respectively; the maximum absorption peaks of its thin film are 688 nm and 753 nm respectively. The maximum absorption peaks of the thin film absorption spectra of PPCy-Ph and PPCy-Br are significantly shifted to the red compared with the maximum absorption peaks of the solution absorption spectra.

[0071] From Figure 5As can be seen, PPCy-Ph and PPCy-Br exhibit similar fluorescence emission peaks in solution and film states. For PPCy-Ph, the maximum emission peak of its solution is 754 nm; the maximum absorption peak of its film is 803 nm. For PPCy-Br, the maximum absorption peak of its solution is 731 nm; the maximum absorption peak of its film is 801 nm. The emission peaks of the fluorescence emission spectra of PPCy-Ph and PPCy-Br films and those of the solution fluorescence emission spectra are both in the near-infrared region, and the emission peaks of the film fluorescence emission spectra are significantly shifted backward compared to those of the solution fluorescence emission spectra. The fact that the spectrum is in the near-infrared region can avoid certain background signals, improve the signal-to-noise ratio of detection, make the detection results more accurate; the absorption or emission characteristics are more obvious, with a higher degree of differentiation from other substances in the environment, thereby improving the sensitivity and selectivity of detection. The red shift of the spectrum broadens the detection range of optical materials, and at the same time can make the energy level structure of the materials more stable, thereby improving the stability of PPCy-Ph and PPCy-Br under conditions such as light and heat and extending their service life.

[0072] Example 5

[0073] Based on the above Examples 3 and 4, the application of PPCy-Br as an anti-counterfeiting material was specifically implemented. Specifically, when applying, 0.7, 0.8, 0.9, 1 mg of PPCy-Br was dissolved in 10 mL of dichloromethane and spin-coated on a glass substrate with a DUT pattern, and then heat-treated for 1 h. As Figure 6 shown, it is the infrared fluorescence picture of the obtained anti-counterfeiting label. As can be seen from Figure 7 it, as the concentration of the compound PPCy-Br increases, the fluorescence intensity of the compound in the film state increases.

[0074] At the same time, further, the fluorescence spectra of the films spin-coated with 1 mg / mL of the compound were tested under different temperature conditions. As can be seen from Figure 8 it, the fluorescence intensity of the compound PPCy-Br in the film state increases with the increase in temperature within the temperature range above the melting point of the compound.

[0075] PPCy-R shows good application potential in the field of anti-counterfeiting display. It emits light outside the visible light range, making the patterns on product labels or bills invisible under ordinary light and detectable only under a specific near-infrared laser sensor, which increases the complexity of anti-counterfeiting. At the same time, it has the ability of light modulation, and it can change its luminescence characteristics according to external stimuli, thereby realizing the display of dynamic patterns.

[0076] In summary, the present invention synthesizes a discotic liquid crystal organic semiconductor compound, and this discotic liquid crystal organic semiconductor material combines the structural tunability of liquid crystal molecules and the photoluminescence of fluorescent molecules. When it is coated on a substrate and irradiated with ultraviolet light, it can only be detected and emit light under a near-infrared laser sensor, and under an external heating field, the fluorescence intensity can be increased, realizing its application in the field of anti-counterfeiting display.

[0077] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A near-infrared light-emitting discotic liquid crystal compound, characterized in that, The structural formula of the said compound is as follows:

2. A method for preparing a near-infrared light-emitting discotic liquid crystal compound as described in claim 1, characterized in that, It includes the following steps: S1. Under the protection of nitrogen, sodium is dissolved in a solvent and reacted at 60 - 130 °C for 1 - 24 h. Subsequently, tris(dodecyl)benzene biphenylcarbonitrile is added into the flask, and a solution of diisopropyl succinate is added by syringe within 2 - 48 h and refluxed for 2 - 48 h. Then acetic acid is injected for acidification for 1 - 5 h. After the reaction ends, it undergoes extraction, separation, and purification treatments in sequence to obtain Compound 1; S2. Under the protection of nitrogen, Compound 1 and Compound 2 are dissolved in a solvent, and then phosphorus oxychloride is added. The reaction continues at 20 - 160 °C for 1 - 72 h. After undergoing extraction, separation, and purification treatments in sequence, Compound 3 is obtained; S3. At room temperature, the said Compound 3 is dissolved in a solvent, and an organic weak base is added dropwise. After reacting for 1 - 60 min, a dichloromethane solution containing 2 - chloro - 1,3,2 - benzenediol borate is added dropwise for reaction. After undergoing extraction, separation, and purification treatments in sequence, the near - infrared light - emitting disc - shaped liquid crystal compound is obtained; 3. The preparation method of the near-infrared light-emitting discotic liquid crystal compound according to claim 2, wherein, In S2, the molar feeding ratio of Compound 1, Compound 2, and phosphorus oxychloride is 1:(1.05 - 1.1):(4 - 6).

4. The preparation method of the near-infrared light-emitting discotic liquid crystal compound according to claim 2, characterized in that In S2, the operating steps of extraction, separation, and purification specifically include: after the reaction ends, saturated sodium carbonate solution is slowly added dropwise to the obtained reaction solution until the pH of the solution is neutral. It is extracted with dichloromethane, and the organic layer is dried with anhydrous sodium sulfate. Finally, the organic solvent is removed by vacuum distillation, and the crude product is separated by a chromatography column to obtain Compound 3.

5. The preparation method of the near-infrared light-emitting discotic liquid crystal compound according to claim 2, characterized in that, In S3, the molar feeding ratio of Compound 3, organic weak base, and 2 - chloro - 1,3,2 - benzenediol borate is 1:(6 - 8):(10 - 12).

6. The preparation method of the near-infrared light-emitting discotic liquid crystal compound according to claim 2, characterized in that, In S3, the operating steps of extraction, separation, and purification specifically include: after the reaction ends, glacial acetic acid is slowly added dropwise to the obtained reaction solution until the pH of the solution is 2 - 7. Then it is extracted with dichloromethane, the organic layers are combined and dried with anhydrous sodium sulfate. Finally, the organic solvent is removed by vacuum distillation, and the crude product is purified by column chromatography to obtain the near - infrared light - emitting disc - shaped liquid crystal compound.

7. Application of a near - infrared light - emitting disc - shaped liquid crystal compound as described in Claim 1 in anti - counterfeiting display.

8. The application according to claim 7, wherein The method of the said application includes: Coating a near - infrared light - emitting disc - shaped liquid crystal compound with a concentration of 0.001 mg / mL - 100 mg / mL on a substrate, and then regulating its photoluminescence intensity by an external field.

9. The application according to claim 8, wherein The said external field includes an external heating field or an external electric field.

10. The application according to claim 8, characterized in that The said coating method includes one of coating method, printing method, spraying method, evaporation method, and sol - gel method; The said substrate includes one of paper, plastic, metal, glass, polymer, and ceramic.

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