Tetracoordinate boron derivative containing CB←N structure, synthesis method and application in preparing near-infrared transmission filter

Abstract

The present invention discloses a class of tetracoordinate boron derivatives containing a C-B←N structure, a synthesis method, and an application in preparing near-infrared transmittance filters. By introducing an imide fragment with a large π-conjugated plane and tetracoordinate boron, the derivatives have excellent molar extinction coefficients and fluorescence quantum yields, good photothermal stability, strong electronegativity, and rigidity, thereby reducing the close packing effect between molecules. The acidic N-H group on the tetracoordinate boron derivative containing a C-B←N structure of the present invention can react with an organic base to expand its absorption spectrum to the near-infrared region. The tetracoordinate boron derivative containing a C-B←N structure is then co-doped with polymethyl methacrylate to prepare a near-infrared transmittance filter with a doping ratio of more than 15% for the tetracoordinate boron derivative. The filter has high near-infrared transmittance, good visible light cutoff capability, good stability, and a long service life, which is conducive to miniaturization of the device and has good application potential in fields such as night vision imaging.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic near-infrared transmitting materials, and in particular relates to a tetracoordinate boron derivative containing a CB←N structure, a synthesis method thereof, and a near-infrared transmitting filter based on the compound. Background Art

[0002] Near-infrared (NIR) filters, which have strong absorption across the entire visible light region and high transmittance in the near-infrared region, are widely used in many fields, including security imaging, night vision, infrared photography, forensic applications, and anti-counterfeiting. To date, common near-infrared filters are usually made from inorganic materials such as metal oxides, silicon-based semiconductors, and chalcogenide glasses. Although these materials have excellent near-infrared transmittance, they also have some inherent limitations, such as high cost, fragility, cumbersome processing, and the need for high-temperature preparation, which greatly hinder their application in many applications. Compared with inorganic materials, organic materials generally have advantages such as flexibility, good solution processability, large-area preparation, and easy adjustment of optical properties. These advantages make them the best candidates for the preparation of near-infrared filters.

[0003] Currently, organic molecules generally have strong absorption capabilities in the short-wave range, with a full width at half maximum (FWHM) of approximately 50 to 150 nm, which cannot meet the requirements of blocking the entire visible light and transmitting near-infrared light. In order to expand the absorption spectrum of organic molecules to 780 nm and above, the commonly used strategy is to extend the π-conjugated skeleton of the molecule or form free radical anions. However, the above methods are often accompanied by disadvantages such as difficult synthesis, poor stability and low solubility. Therefore, there is an urgent need to find a simple and effective strategy to control the transmittance range in the near-infrared region.

[0004] Perylene monoimide fragments possess a large π-conjugated plane, excellent molar extinction coefficients and fluorescence quantum yields, and good photothermal stability. Furthermore, due to the electron-withdrawing imide structure, the entire molecule exhibits strong electronegativity and is often used as an electron acceptor material. By attaching electron-donating fragments to the perylene monoimide structure to form a DA system, its photophysical properties can be effectively modulated. Through rational structural modification, it is even possible to red-shift the strong optical absorption from the visible region to the near-infrared region. However, due to the strong intermolecular stacking interaction of perylene monoimide, its derivatives are prone to H-aggregation, resulting in a decrease in the material's solubility, which in turn affects its practical application. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a class of tetracoordinate boron derivatives containing a CB←N structure with high stability and solubility and strong absorption in the entire visible light region, and to provide a simple synthesis method for the derivatives, while also providing a new use for the derivatives.

[0006] To achieve the above-mentioned purpose, the present invention provides a tetracoordinate boron derivative containing a CB←N structure, the structural formula of which is as follows:

[0007]

[0008] Where, represents any one of the following groups:

[0009]

[0010] R represents C1~C 20 Any one of a straight chain or branched chain alkyl group, and a phenyl group substituted with a C1 to C6 straight chain or branched chain alkyl group.

[0011] The synthesis method of the tetracoordinate boron derivative containing the CB←N structure comprises the following steps:

[0012] Step 1: Synthesis of compound 2

[0013] Under nitrogen atmosphere, compound 1, 2-aminopyridine, sodium tert-butoxide, tris(dibenzylideneacetone)palladium, and tri-tert-butylphosphine were mixed uniformly in anhydrous toluene, and then stirred at 80-120° C. for 20-25 hours. After the reaction was completed, the mixture was naturally cooled to room temperature, and the toluene was removed by evaporation under reduced pressure. The crude product was separated and purified by column chromatography to obtain solid compound 2. The reaction equation is as follows:

[0014]

[0015] The compound 1 represents any one of the following compounds:

[0016]

[0017] Among them, R represents C1~C 20 Any one of a straight chain or branched chain alkyl group, a C1 to C6 straight chain or branched chain alkyl substituted phenyl group;

[0018] Step 2: Synthesis of tetracoordinate boron derivatives containing CB←N structure

[0019] Under nitrogen atmosphere, compound 2, potassium phenyltrifluoroborate, and N,N-diisopropylethylamine were mixed uniformly in anhydrous toluene, and then silicon tetrachloride was added dropwise. The mixture was stirred at room temperature for 30 to 40 minutes, heated to 130 to 160°C, reacted for 15 to 24 hours, and naturally cooled to room temperature. The toluene was removed by evaporation under reduced pressure, and separated by column chromatography to obtain a tetracoordinate boron derivative containing a CB←N structure. The reaction equation is as follows:

[0020]

[0021] In the above step 1, the molar ratio of compound 1, 2-aminopyridine, sodium tert-butoxide, tris(dibenzylideneacetone)palladium, and tri-tert-butylphosphine is preferably 1:1.2-1.5:1-1.2:0.01-0.1:0.5-0.6.

[0022] In the above step 2, the molar ratio of compound 2, potassium phenyltrifluoroborate, N,N-diisopropylethylamine, and silicon tetrachloride is preferably 1:2.2-2.5:3.5-4:1-1.2.

[0023] The tetracoordinate boron derivative containing the CB←N structure of the present invention can be used to prepare a near-infrared transparent filter. The specific preparation method includes the following steps:

[0024] Step 1: dispersing a tetracoordinate boron derivative containing a CB←N structure in NN-dimethylformamide, then adding an organic base, and sonicating the mixed solution for 5 to 10 minutes to form a homogeneous solution; the organic base is any one of 1,8-diazabicycloundec-7-ene (DBU), tetrabutylammonium fluoride, and tetrabutylammonium hydroxide;

[0025] Step 2: Dispersing polymethyl methacrylate (PMMA) with a number average molecular weight of 30,000 to 40,000 in NN-dimethylformamide, heating at 90 to 110° C. until completely dissolved to obtain a uniform solution;

[0026] Step 3: uniformly mixing the uniform solution of step 1 and the uniform solution of step 2, so that the mass ratio of the tetracoordinate boron derivative containing CB←N structure to polymethyl methacrylate in the resulting mixed solution is 15 to 20:100;

[0027] Step 4: Spread the mixed solution obtained in step 3 onto a quartz glass plate, and dry it at 100-120°C for 10-12 hours to obtain a near-infrared transmittance filter.

[0028] In the above step 1 of preparing the near-infrared transparent filter, the concentration of the tetracoordinate boron derivative containing the CB←N structure in the homogeneous solution is preferably 10-15 mg / mL.

[0029] In the above step 1 of preparing the near-infrared transmittance filter, the amount of the organic base added is preferably 10 to 20 times the molar amount of the tetracoordinate boron derivative containing the CB←N structure.

[0030] In the above step 2 of preparing the near-infrared transparent filter, the concentration of polymethyl methacrylate in the homogeneous solution is preferably 80 to 120 mg / mL.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The tetracoordinate boron derivatives of the present invention, containing a CB←N structure, incorporate an imide fragment with a large π-conjugated plane, resulting in such derivatives having excellent molar extinction coefficients and fluorescence quantum yields, while also exhibiting good photothermal stability. Furthermore, influenced by the electron-withdrawing imide structure, the entire molecule exhibits a strong electronegativity and is often used as an electron acceptor material. By connecting the electron-donating fragment to the conjugated plane with the imide structure to form a DA system, its photophysical properties can be effectively modulated. Simultaneously, the introduction of tetracoordinate boron imparts a strong rigidity to the entire molecule, with sp3 hybridization forming a regular tetrahedral configuration, which effectively suppresses the strong interactions between the molecular conjugated planes and reduces the close packing of molecules.

[0033] 2. The synthesis method of the tetracoordinate boron derivative containing the CB←N structure of the present invention is simple to operate, the raw materials are readily available, the equipment requirements are low, and it is applicable to fragments containing different substituents.

[0034] 3. The acidic NH groups on the tetracoordinate boron derivatives containing a CB←N structure of the present invention can react with organic bases such as DBU to form deprotonated products, causing changes in both UV-visible absorption and fluorescence spectra. After acid treatment, these spectra return to their original state. Based on this reaction, the present invention uses tetracoordinate boron derivatives containing a CB←N structure to prepare near-infrared-transmitting filters. This method is simple to operate and requires mild reaction conditions. The prepared near-infrared-transmitting filters exhibit high near-infrared transmittance, excellent visible light cutoff, excellent stability, and a long service life, representing an excellent class of organic near-infrared-transmitting materials. The near-infrared-transmitting filters obtained by the present invention can be used in night vision imaging and information protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the H NMR spectrum of the tetracoordinate boron derivative containing the CB←N structure synthesized in Example 1.

[0036] Figure 2 This is a high-resolution mass spectrum of the tetracoordinate boron derivative containing the CB←N structure synthesized in Example 1.

[0037] Figure 3This is the UV-visible-near infrared absorption spectrum of the reaction between the tetracoordinate boron derivative containing CB←N structure synthesized in Example 1 and an organic base.

[0038] Figure 4 It is a schematic diagram of the preparation process of the near-infrared transparent filter of the present invention.

[0039] Figure 5 This is a microscopic morphology of the near-infrared transparent filter prepared in Example 5.

[0040] Figure 6 It is the transmission spectrum measured at different positions of the near-infrared transmittance filter.

[0041] Figure 7 This is a thickness diagram of the near-infrared transmittance filter prepared in Example 5.

[0042] Figure 8 1 is the transmission spectrum of the near-infrared transmittance filter prepared in Example 5 at different temperatures.

[0043] Figure 9 This is a photo taken in a dark environment by a mobile phone modified with the near-infrared transparent filter prepared in Example 5. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments and drawings. Obviously, the description is for explanation rather than limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0045] In the following examples, compound 1-1 was synthesized according to the method in “Mater. Chem. Front. 2019, 3, 1218-1224”.

[0046]

[0047] In the following examples, compounds 1-2 were prepared according to the method described in J. Phys. Chem. B 2011, 115, 14648-14658.

[0048]

[0049] In the following examples, compounds 1-3 were prepared according to the method provided in the literature “Chem. Eur. J. 2009, 15, 9299-9302”.

[0050]

[0051] In the following examples, compounds 1-4 were prepared according to the method provided in the literature "Angew. Chem. Int. Ed. 2006, 45, 1401-1404", except that the molar ratio of the 9-substituted perylene monoimide borate to 1,4-dibromonaphthalene was changed to 1:1.

[0052]

[0053] Example 1

[0054] Step 1: Synthesis of compound 2-1

[0055] Weigh 0.512g (1mmol) of compound 1-1, 0.141g (1.5mmol) of 2-aminopyridine, 0.116g (1.2mmol) of sodium tert-butoxide, and 0.092g (0.1mmol) of tris(dibenzylideneacetone)palladium into a 100mL Shrek bottle. Evacuate the reaction vessel and fill it with nitrogen. Repeat the above operation three times to provide an oxygen-free environment. Then, add 40mL of anhydrous toluene and 117μL (0.5mmol) of tri-tert-butylphosphine to the container with a syringe. Stir and react at 80°C for 24 hours. After the reaction is completed, cool naturally to room temperature, remove toluene by evaporation under reduced pressure, and the crude product is separated and purified by column chromatography. The eluent is a mixture of dichloromethane and methanol in a volume ratio of 100:1 to obtain a purple solid, which is compound 2-1. The reaction equation is as follows:

[0056]

[0057] Step 2: Synthesis of tetracoordinate boron derivatives containing CB←N structure

[0058] 0.158 g (0.3 mmol) of compound 2-1 and 0.133 g (0.72 mmol) of potassium phenyltrifluoroborate were placed in a 25 mL Shrek tube. The reaction vessel was evacuated and filled with nitrogen. This operation was repeated three times to provide an oxygen-free environment. 5 mL of anhydrous toluene and 0.189 mL (1.08 mmol) of N,N-diisopropylethylamine were then added to the reaction vessel using a syringe. 32 μL (0.3 mmol) of SiCl4 was then slowly added dropwise to the reaction vessel using a microsyringe. The resulting mixed solution was stirred at room temperature for 30 minutes, heated to 155°C, reacted for 20 hours, and naturally cooled to room temperature. The toluene was evaporated under reduced pressure and separated by column chromatography using dichloromethane as the eluent to obtain a purple-black solid, which is a tetracoordinate boron derivative containing a CB←N structure, designated PMI-CBN. The reaction equation is as follows:

[0059]

[0060] The structural characterization data of the obtained PMI-CBN are as follows Figures 1-2 shown.

[0061] The obtained PMI-CBN was prepared with dichloromethane as solvent at a concentration of 1×10 -4 mol / L PMI-CBN solution; tetrabutylammonium fluoride was prepared with dichloromethane as solvent to prepare a 0.001 mol / L tetrabutylammonium fluoride solution; 0.15 mL PMI-CBN solution was diluted to 3 mL, and the test concentration was 5 × 10 -6 mol / L, and then 3.75μL of tetrabutylammonium fluoride solution was added gradually, mixed evenly and tested on a Perkin-Elmer Lambd 1050 spectrometer to obtain Figure 3 The UV-visible-near infrared absorption spectra of PMI-CBN solutions with 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, and 2.0 equivalents of tetrabutylammonium fluoride added are shown. Figure 3 It can be seen that with the addition of tetrabutylammonium fluoride, the absorption peak at 450-650 nm gradually decreases and disappears, while a new absorption peak is generated at 650-900 nm, indicating that the absorption spectrum range of the derivative can be effectively adjusted by reacting it with an organic base.

[0062] Example 2

[0063] Step 1: Synthesis of compound 2-2

[0064] Weigh 166 mg (0.5 mmol) of compound 1-2, 61 mg (0.65 mmol) of 2-aminopyridine, 57.9 mg (0.6 mmol) of sodium tert-butoxide, and 4.6 mg (0.005 mmol) of tris(dibenzylideneacetone)palladium into a 15 mL Shrek bottle. Evacuate the reaction vessel and fill it with nitrogen. Repeat the above operation three times to provide an oxygen-free environment. Then, add 2.5 mL of anhydrous toluene and 59 μL (0.25 mmol) of tri-tert-butylphosphine to the container using a syringe. Stir and react at 120°C for 24 hours. After the reaction is completed, cool naturally to room temperature, remove toluene by evaporation under reduced pressure, and the crude product is purified by column chromatography using dichloromethane as the eluent to obtain an orange solid, which is compound 2-2. The reaction equation is as follows:

[0065]

[0066] Step 2: Synthesis of tetracoordinate boron derivatives containing CB←N structure

[0067] 60 mg (0.17 mmol) of compound 2-2 and 77 mg (0.42 mmol) of potassium phenyltrifluoroborate were placed in a 25 mL Shrek tube. The reaction vessel was evacuated and filled with nitrogen. This operation was repeated three times to provide an oxygen-free environment. 3 mL of anhydrous toluene and 110 μL (0.63 mmol) of N,N-diisopropylethylamine were then added to the reaction vessel using a syringe. 20 μL (0.17 mmol) of SiCl4 was then measured using a microsyringe and slowly added dropwise to the reaction vessel. The resulting mixed solution was stirred at room temperature for 30 minutes, heated to 135°C, reacted for 24 hours, and naturally cooled to room temperature. The toluene was evaporated under reduced pressure and separated by column chromatography using dichloromethane as the eluent to obtain a yellow solid, which was a tetracoordinate boron derivative containing a CB←N structure. The reaction equation is as follows:

[0068]

[0069] Example 3

[0070] Step 1: Synthesis of Compound 2-3

[0071] In step 1 of Example 1, the compound 1-1 used was replaced with an equal mole of compound 1-3, and the other steps were the same as step 1 of Example 1 to obtain compound 2-3. The reaction equation is as follows:

[0072]

[0073] Step 2: Synthesis of tetracoordinate boron derivatives containing CB←N structure

[0074] In step 2 of Example 1, the compound 2-1 used was replaced with an equal mole of compound 2-3. The other steps were the same as those in step 2 of Example 1 to obtain a tetracoordinate boron derivative containing a CB←N structure. The reaction equation is as follows:

[0075]

[0076] Example 4

[0077] Step 1: Synthesis of compounds 2-4

[0078] In step 1 of Example 1, the compound 1-1 used was replaced with an equal mole of compound 1-4, and the other steps were the same as step 1 of Example 1 to obtain compound 2-4. The reaction equation is as follows:

[0079]

[0080] Step 2: Synthesis of tetracoordinate boron derivatives containing CB←N structure

[0081] In step 2 of Example 1, the compound 2-1 used was replaced with an equal mole of compound 2-4. The other steps were the same as those in step 2 of Example 1 to obtain a tetracoordinate boron derivative containing a CB←N structure. The reaction equation is as follows:

[0082]

[0083] Example 5

[0084] The application of PMI-CBN in Example 1 in preparing near-infrared filters, such as Figure 4 As shown, the specific preparation method is as follows:

[0085] Step 1: Place 12.5 mg (0.018 mmol) of PMI-CBN in a 5 mL glass bottle, add 1 mL of NN-dimethylformamide, and then add 50 μL (0.33 mmol) of DBU. Ultrasonicate the mixture for 5 minutes to form a homogeneous solution, i.e., a PMI-CBN solution with a concentration of 12.5 mg / mL. Allow to stand, seal, and store for later use.

[0086] Step 2: Disperse 100 mg of PMMA with a number average molecular weight of 35,000 in 1 mL of NN-dimethylformamide and heat at 100°C until completely dissolved to obtain a PMMA solution with a concentration of 100 mg / mL. Allow to stand, seal, and store for future use.

[0087] Step 3: Use a pipette to accurately measure 48 μL of the PMI-CBN solution described in step 1 and 40 μL of the PMMA solution described in step 2 into a microcentrifuge tube. After high-speed oscillation for 1 minute, a uniform solution is obtained. The mass ratio of the tetracoordinate boron derivative containing a CB←N structure to polymethyl methacrylate in this solution is 15:100.

[0088] Step 4: A 16 mm diameter circular quartz glass sheet was washed with ethanol and dried, and then the surface was further cleaned using a plasma cleaner. The solution described in step 3 was dropwise applied to the cleaned quartz glass sheet, and the sheet was dried in an oven at 100°C for 12 hours to produce a near-infrared transmittance filter.

[0089] Various experiments were conducted on the prepared near-infrared filter, as follows:

[0090] (1) Surface uniformity test of near-infrared filter

[0091] The dispersion of dyes in PMMA will affect all aspects of the material's performance, so it is very necessary to study the surface uniformity of the filter. Figure 5 As shown, it can be seen that the dye is evenly dispersed in the PMMA matrix without obvious particles. Figure 6The transmittance tests at three different positions of the same filter show that the test curves are basically consistent, indicating that the filter has good uniformity both macroscopically and microscopically.

[0092] (2) Filter thickness test

[0093] The thickness of the filter was observed using a scanning electron microscope. Figure 7 It can be seen that the thickness of the filter is only 16μm, which helps to apply it to small devices.

[0094] (3) Thermal stability test of filters

[0095] In order to cope with the application of filters in different scenarios, we also tested their thermal stability. We placed the filters in an oven at 80, 90, 100, and 120°C for 4 hours and tested their transmission spectra. Figure 8 As shown, the spectrum has only slight intensity changes, indicating that the filter has excellent thermal stability.

[0096] (4) Performance of filters in practical applications

[0097] The prepared near-infrared transmitting filter is used to replace the near-infrared reflecting filter in the mobile phone lens to obtain a modified mobile phone that can collect near-infrared information. Figure 9 It can be seen that a normal mobile phone cannot capture objects in a dark environment, but the modified mobile phone can capture objects more clearly (using 1050nm near-infrared light as the light source), which shows that this filter has good application potential in night vision imaging.

[0098] In summary, the near-infrared filter prepared using the tetracoordinate boron derivative containing the CB←N structure of the present invention has high near-infrared transmittance and extremely low visible light transmittance, as well as excellent thermal stability and thin thickness, which is conducive to the miniaturization of the device and is extremely practical.

Claims

1. A tetracoordinate boron derivative containing a CB←N structure, characterized in that: Its structural formula is shown below: Where, Represents the following groups: R represents C1~C 20 Any one of a straight chain or branched chain alkyl group, and a phenyl group substituted with a C1 to C6 straight chain or branched chain alkyl group.

2. A method for synthesizing the tetracoordinate boron derivative containing the CB←N structure according to claim 1, characterized in that: The following steps are involved: Step 1: Synthesis of compound 2 Under nitrogen atmosphere, compound 1, 2-aminopyridine, sodium tert-butoxide, tris(dibenzylideneacetone)palladium, and tri-tert-butylphosphine were mixed uniformly in anhydrous toluene, and then stirred at 80-120°C for 20-25 hours. After the reaction was completed, the mixture was naturally cooled to room temperature and the toluene was removed by evaporation under reduced pressure. The crude product was separated and purified by column chromatography to obtain solid compound 2. The reaction equation is as follows: The compound 1 represents the following compound: Among them, R represents C1~C 20 Any one of a straight chain or branched chain alkyl group, a C1 to C6 straight chain or branched chain alkyl substituted phenyl group; Step 2: Synthesis of tetracoordinate boron derivatives containing CB←N structure Under nitrogen atmosphere, compound 2, potassium phenyltrifluoroborate, and N,N-diisopropylethylamine were mixed uniformly in anhydrous toluene, and then silicon tetrachloride was added dropwise. The mixture was stirred at room temperature for 30 to 40 minutes, heated to 130 to 160°C, and reacted for 15 to 24 hours. The mixture was naturally cooled to room temperature, and the toluene was removed by evaporation under reduced pressure. After column chromatography, a tetracoordinate boron derivative containing a CB←N structure was obtained. The reaction equation is as follows: 。 3. The method for synthesizing a tetracoordinate boron derivative containing a CB←N structure according to claim 2, wherein: In step 1, the molar ratio of the compound 1, 2-aminopyridine, sodium tert-butoxide, tris(dibenzylideneacetone)palladium, and tri-tert-butylphosphine is 1:1.2-1.5:1-1.2:0.01-0.1:0.5-0.

6.

4. The method for synthesizing a tetracoordinate boron derivative containing a CB←N structure according to claim 2, wherein: In step 2, the molar ratio of compound 2, potassium phenyltrifluoroborate, N,N-diisopropylethylamine, and silicon tetrachloride is 1:2.2-2.5:3.5-4:1-1.

2.

5. Use of the tetracoordinate boron derivative containing the CB←N structure according to claim 1 in the preparation of near-infrared transparent filters.

6. Use of the tetracoordinate boron derivative containing a CB←N structure according to claim 5 in the preparation of a near-infrared transmittance filter, characterized in that The specific preparation method comprises the following steps: Step 1: dispersing a tetracoordinate boron derivative containing a CB←N structure in NN-dimethylformamide, then adding an organic base, and sonicating the mixed solution for 5 to 10 minutes to form a homogeneous solution; the organic base is any one of 1,8-diazabicycloundec-7-ene, tetrabutylammonium fluoride, and tetrabutylammonium hydroxide; Step 2: Dispersing polymethyl methacrylate with a number average molecular weight of 30,000 to 40,000 in NN-dimethylformamide, heating at 90 to 110° C. until completely dissolved to obtain a uniform solution; Step 3: uniformly mixing the uniform solution of step 1 and the uniform solution of step 2, so that the mass ratio of the tetracoordinate boron derivative containing CB←N structure to polymethyl methacrylate in the resulting mixed solution is 15 to 20:100; Step 4: drop the mixed solution obtained in step 3 onto a quartz glass plate, and dry it at 100-120° C. for 10-12 hours to prepare a near-infrared transmittance filter.

7. Use of the tetracoordinate boron derivative containing a CB←N structure according to claim 6 in the preparation of a near-infrared transparent filter, characterized in that: In step 1, the concentration of the tetracoordinate boron derivative containing the CB←N structure in the homogeneous solution is 10-15 mg / mL.

8. Use of the tetracoordinate boron derivative containing a CB←N structure according to claim 6 in the preparation of a near-infrared transparent filter, characterized in that: In step 1, the amount of the organic base added is 10 to 20 times the molar amount of the tetracoordinate boron derivative containing the CB←N structure.

9. Use of the tetracoordinate boron derivative containing a CB←N structure according to claim 6 in the preparation of a near-infrared transparent filter, characterized in that: In step 2, the concentration of polymethyl methacrylate in the homogeneous solution is 80-120 mg / mL.

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