A novel hydroxyl-containing dihydropyridine photosensitizer, its preparation method and application

Abstract

The application relates to the technical field of photosensitive organic compound synthesis, and discloses a novel hydroxyl-containing dihydropyridine photosensitizer and a preparation method and application thereof, wherein the method comprises the following steps: taking 5-hydroxy-2-nitrobenzaldehyde as a starting raw material, reacting with 3-amino-tiglic acid phenyl acid methyl ester under the catalysis of trifluoroformic acid, precipitating, filtering and recrystallizing the product to obtain photosensitive dihydropyridine monomers; taking 3,5-dibromophenol as a starting raw material, introducing a halogenated straight-chain alkyl with a terminal halogen at the hydroxyl position of the 3,5-dibromophenol; dissolving the photosensitive dihydropyridine monomers and the intermediate A, and performing a substitution reaction under the action of alkali to prepare an intermediate B; performing a Suzuki coupling reaction on the intermediate B and 4-hydroxymethylphenylboronic acid to finally obtain the novel hydroxyl-containing dihydropyridine photosensitizer. The novel hydroxyl-containing dihydropyridine photosensitizer (DHPDO) compound is stable, the preparation process is simple, the intermediate product has high stability, and the post-treatment and purification are low-toxicity and harmless.

Description

Technical Field

[0001] The present invention relates to the technical field of synthesis of photosensitivity organic compounds, and in particular to a novel hydroxyl-containing dihydropyridine photosensitizer, a preparation method and application thereof. Background Art

[0002] In today's digitally interconnected world, ensuring the secure transmission of information has become a top priority. However, the ubiquity of light poses a significant challenge to materials that respond to a single stimulus, such as traditional fluorescent or phosphorescent materials, making them more vulnerable to potential attacks. A variety of materials, including lanthanide-doped materials, aggregation-induced emission (AIE) materials, room-temperature phosphorescent (RTP) materials, molecular probes, metal-organic frameworks (MOFs), polymer fluorescent nanoparticles (NPs), and host-guest systems, are currently used for optical encryption. Among these materials, polymer thin film materials are often used in information encryption applications due to their simplicity, portability, and ease of physical shape adjustment.

[0003] Polyurethane (PU) is a viable material due to its remarkable controllability. Researchers can use PU as a host matrix and introduce various functional moieties to create films with diverse applications. The integration of various hard and soft segments in PU introduces responsive properties to various external stimuli. This controllable design not only enhances the versatility and flexibility of information encryption but also overcomes the limitations of materials that rely on a single stimuli-responsive mechanism. For example, the incorporation of soft segments such as polycaprolactone (PCL), castor oil (CO), and polytetramethylene ether glycol (PTMEG) can impart shape memory properties to PU. These tailored properties make PU an ideal candidate for information encryption. To impart dynamic and reversible properties to polymers, researchers have introduced specific dynamic moieties or substances into the polymer network. Examples include disulfide bonds (-SS-), oxime bonds, urea bonds, and dynamic covalent bonds. This unique functionality expands the applicability of PU beyond encryption to include adaptive smart windows and high-strength adhesives. The versatility of PU highlights its strategic importance, not only in protecting sensitive information but also in promoting development in diverse fields. Therefore, photosensitive polyurethanes are an excellent choice for pattern preparation in anti-counterfeiting labels. Photosensitive polyurethanes can be produced through the polycondensation reaction of photosensitive diols with reactive isocyanates. However, existing technologies for preparing photosensitive diols have low production efficiency, and the prepared photosensitive diols are also unstable and difficult to store at room temperature and pressure, making large-scale production of photosensitive diols impossible. Therefore, to address the shortcomings of poor stability of photosensitive diols and the low production efficiency caused by low conversion rates of intermediate products in their preparation, there is an urgent need to improve existing technologies.

[0004] The present invention utilizes the addition of photosensitive functional units to polyurethane to achieve light response, thereby realizing the special application of polyurethane in optical encryption. This provides further innovative value for the design and implementation of multifunctional information encryption. Summary of the Invention

[0005] To address the above-mentioned deficiencies in the prior art, the present invention aims to provide a method for preparing a photosensitive functional biphenyl diol, which is simple in preparation, has a high yield, and has a strong stability of the intermediate product. The obtained new hydroxyl-containing dihydropyridine photosensitizer has strong stability and ultraviolet light sensitivity, and can be introduced as a photosensitive group in the synthesis of photosensitive polyurethane.

[0006] To achieve the above objectives, the present invention provides a novel hydroxyl-containing dihydropyridine photosensitizer, the molecular structure of which is as follows:

[0007]

[0008] According to another aspect of the present invention, the present invention also provides a method for synthesizing a novel hydroxyl-containing dihydropyridine photosensitizer, comprising the following steps:

[0009] S1. Using 5-hydroxy-2-nitrobenzaldehyde as a starting material, reacting with 3-aminocrotonobenzoic acid methyl ester in an anhydrous polar organic solvent at a reaction temperature of 0-10° C. under the catalysis of trifluoromethane, the reaction product is precipitated, filtered, and recrystallized to obtain a photosensitive dihydropyridine monomer having the following structural formula:

[0010]

[0011] S2. Using 3,5-dibromophenol as a starting material, a halogenated linear alkyl group with a halogen terminal is introduced into the hydroxyl position of 3,5-dibromophenol to prepare intermediate A;

[0012] S3, dissolving the photosensitive dihydropyridine monomer and intermediate A in a polar organic solvent, and in the presence of a base, causing the hydroxyl group of the photosensitive dihydropyridine monomer to undergo a substitution reaction with the halogen group at the end of the halogenated linear alkyl group on intermediate A to obtain intermediate B;

[0013] S4. Intermediate B is subjected to a Suzuki coupling reaction with 4-hydroxymethylphenylboronic acid to finally obtain a novel hydroxyl-containing dihydropyridine photosensitizer.

[0014] As a further preferred technical solution of the present invention, in step S2: 3,5-dibromophenol is dissolved in a polar organic solvent, and a dihalogenated straight-chain alkane containing a halogen at the end is added to the solution in a reaction environment in the presence of a base. The halogen at one end of the dihalogenated straight-chain alkane reacts with the hydroxyl group on the 3,5-dibromophenol through nucleophilic substitution to form an ether bond, thereby preparing intermediate A.

[0015] As a further preferred technical solution of the present invention, the dihalogenated straight-chain alkane containing a halogen at the end is 1,4-dihalobutane, and the halogen atom thereof is Cl, Br or I.

[0016] As a further preferred technical solution of the present invention, in step S3: intermediate A is dissolved in a polar organic solvent, and a photosensitive dihydropyridine monomer is added to the solution in a reaction environment in the presence of a base, and the hydroxyl group of the photosensitive dihydropyridine monomer reacts with the halogen in intermediate A through nucleophilic substitution to form an ether bond, thereby obtaining intermediate B.

[0017] As a further preferred technical solution of the present invention, in step S4: intermediate B and 4-hydroxymethylphenylboronic acid are added to a polar organic solvent, and a catalytic amount of tetrakis(triphenylphosphine)palladium is added, and the mixture is stirred and refluxed under an inert atmosphere in a reaction environment in the presence of a base to obtain a novel hydroxyl-containing dihydropyridine photosensitizer.

[0018] As a further preferred technical solution of the present invention, the polar organic solvent is selected from at least one of methanol, ethanol, tetrahydrofuran, chloroform, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0019] As a further preferred technical solution of the present invention, the base is selected from at least one of lithium carbonate, potassium carbonate, sodium carbonate, rubidium carbonate, cesium carbonate, beryllium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, and barium carbonate.

[0020] According to another aspect of the present invention, the present invention also provides a use of a novel hydroxyl-containing dihydropyridine photosensitizer in the preparation of photosensitive polyurethane.

[0021] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0022] 1) The novel hydroxyl-containing dihydropyridine photosensitizer (DHPDO) compound of the present invention is stable, has a simple preparation process, has a strong stability of the intermediate product, and is low-toxic and harmless after post-processing and purification (the product can be purified by operations such as sedimentation, beating, and recrystallization);

[0023] 2) The preparation process of the novel hydroxyl-containing dihydropyridine photosensitizer (DHPDO) compound of the present invention is simple and easy to operate, easy to industrialize, and has low production cost. The present invention is the first to synthesize this novel hydroxyl-containing dihydropyridine photosensitizer, and it can be applied to the synthesis of photosensitive polyurethanes, forming a photosensitizing polyurethane with a rigid main chain and a certain degree of flexibility in the side chain. Due to the presence of photosensitive groups, its application as a functional molecule is greatly expanded, and it is expected that this polyurethane will be used in information storage and anti-counterfeiting applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] Figure 1 This is a mass spectrum of the pyridine structure formed after the novel hydroxyl-containing dihydropyridine photosensitizer (DHPDO) of the present invention is dehydrated under ultraviolet light.

[0026] Figure 2 The synthetic route diagram of the novel dihydropyridine photosensitizer (DHPDO) of the present invention is shown in FIG.

[0027] Figure 3 (DMSO-d6) of the photosensitive dihydropyridine monomer (NDHP) of Example 1 1 HNMR spectrum.

[0028] Figure 4 (CDCl3) of the intermediate A of Example 1 1 HNMR spectrum.

[0029] Figure 5 (DMSO-d6) of the intermediate B of Example 1 1 HNMR spectrum.

[0030] Figure 6 (DMSO-d6) of the novel hydroxyl-containing dihydropyridine photosensitizer (DHPDO) of Example 1 1 HNMR spectrum.

[0031] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0032] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0033] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which this invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are conventional biochemical reagents; the experimental methods described, unless otherwise specified, are conventional methods.

[0034] The present invention provides a novel hydroxyl-containing dihydropyridine photosensitizer (DHPDO), whose molecular structure is as follows:

[0035]

[0036] The photosensitizer (DHPDO) is based on the sensitivity of the dihydropyridine unit to ultraviolet light. Under ultraviolet light, its structure can undergo intramolecular dehydration reaction, thereby achieving its photosensitivity. The photosensitivity of DHPDO can be verified by mass spectrometry characterization, such as Figure 1 shown.

[0037] Example 1:

[0038] This embodiment provides a method for preparing a novel hydroxyl-containing dihydropyridine photosensitizer (DHPDO). The synthesis route is as follows: Figure 2 As shown, the details are as follows:

[0039] (1) Synthesis of photosensitive dihydropyridine monomer (NDHP)

[0040] A1. Weigh 16.712 g (10 mmol, 1 eq) of 5-hydroxy-2-nitrobenzaldehyde and dissolve it in an appropriate amount of ethanol to form a homogeneous solution. Then, add 27 ml (3.5 mmol, 3 eq) of trifluoroacetic acid while stirring in an ice bath at 0°C.

[0041] A2. Dissolve 34.54 g (30 mmol, 3 eq) of 3-aminocrotonate methyl ester in 150 ml of anhydrous ethanol. Gradually add 3-aminocrotonate methyl ester in anhydrous ethanol (150 ml) to the solution of A1 at 0 ° C in an ice bath and react at 0 ° C in an ice bath for 8 h.

[0042] A3. After the reaction is complete, add a large amount of deionized water to precipitate, filter, and dissolve the intercepted product with a small amount of ethanol by heating, and recrystallize to obtain the purified target product NDHP, which is weighed after drying (yield is 70%). Figure 3 of 1 HNMR characterization confirmed.

[0043] (2) Synthesis of intermediate A

[0044] B1. Dissolve 3,5-dibromophenol (10.00 g, 39.70 mmol) and 1,4-dihalobutane (3 eq, 59.55 mmol) in 100 mL of acetone, add K2CO3 (16.46 g, 119.09 mmol), and reflux at 80°C under an inert atmosphere for 48 h. The halogen atom of 1,4-dihalobutane is Br, but can also be Cl or I.

[0045] B2. After the reaction, the reaction solution was cooled to room temperature, washed with petroleum ether, and purified by silica gel column chromatography under reduced pressure to obtain intermediate A (x is Br) as a colorless transparent liquid (yield 90%). Figure 4 of 1 HNMR characterization confirmed.

[0046] (3) Synthesis of intermediate B

[0047] C1. NDHP (3.15 g, 8.70 mmol) was dissolved in acetone (150 mL), and K2CO3 (10.81 g, 78.33 mmol) was added. Intermediate A (1 eq, 26.11 mmol) was added to the reaction system under an inert gas atmosphere at 80°C. The mixture was stirred under reflux for 36 h.

[0048] C2. After the reaction, the mixture was washed with petroleum ether and purified by silica gel column chromatography to obtain intermediate B (x is Br) as a light yellow solid (yield: 60%). Figure 5 of 1 The results were confirmed by H NMR spectroscopy (DMSO-d6).

[0049] (4) Synthesis of photosensitive dihydropyridine monomer (DHPDO)

[0050] D1. In a 500 mL flask, tetrahydrofuran (100 mL) was added to dissolve intermediate B (1 eq, 19.83 mmol) to obtain a homogeneous mixed solution. 2 M aqueous K2CO3 solution (70 mL) and 4-hydroxymethylphenylboronic acid (5.71 g, 49.58 mmol) were then added, and the mixture was purged with inert gas for 30-60 min.

[0051] D2. Rapidly add tetrakis(triphenylphosphine)palladium(0)(Pd[P(C6H5)3]4))(0.02eq, 0.397mmol) of catalyst amount to the above mixed solution, under an inert gas atmosphere, stir and reflux for 72h;

[0052] D3. After the reaction, the oily substance washed with petroleum ether was dissolved in a small amount of methanol solution, and a large amount of deionized water was used to precipitate and purify the product. Finally, a new hydroxyl-containing dihydropyridine photosensitizer (DHPDO) was obtained (yield 76%). Figure 6 of 1 The identification was confirmed by H NMR.

[0053] Example 2:

[0054] This embodiment provides a method for preparing photosensitive polyurethane based on a novel hydroxyl-containing dihydropyridine photosensitizer, as follows:

[0055] (1) Toluene diisocyanate (TDI) (16.8 mmol) was injected into a magnetically stirred inert gas atmosphere container and stirred in an ice bath at 0°C for 10 min;

[0056] (2) In an inert atmosphere glove box, the weighed dihydropyridine novel photosensitizer monomer (DHPDO) of the present invention (1 mmol) was dissolved in an anhydrous N,N-diethylformamide (DMF) and dimethyl sulfoxide (DMSO) mixed solvent (DMF:DMSO = 4:1, v / v);

[0057] (3) Inject a solution of a mixed solvent containing a novel dihydropyridine photosensitizer monomer (DHPDO) dropwise in an ice bath at 0°C and stir in an ice bath for 1.5 h;

[0058] (4) 15 mmol of 1,4-dibutanol (BDO) was added dropwise under an ice bath at 0°C, and then the ice bath was removed. The mixture was stirred at room temperature for 12 h, heated at 40°C for 12 h, and heated at 60°C for 12 h to obtain a photosensitive polyurethane solution.

[0059] (5) Spin-coat the photosensitive polyurethane solution on a glass substrate with a thickness of 100 μm, evaporate the solvent (dry), and obtain a photosensitive polyurethane film.

[0060] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A method for synthesizing a novel hydroxyl-containing dihydropyridine photosensitizer, characterized in that: The following steps are involved: S1. Using 5-hydroxy-2-nitrobenzaldehyde as a starting material, reacting with methyl 3-aminocrotonate in an anhydrous polar organic solvent at a temperature of 0-10° C. under the catalysis of trifluoroacetic acid, the reaction product is precipitated, filtered, and recrystallized to obtain a photosensitive dihydropyridine monomer having the following structural formula: ； S2. Dissolve 3,5-dibromophenol in a polar organic solvent. Add a dihalogenated straight-chain alkane containing a halogen at the end to the solution in the presence of a base. React the halogen at one end of the dihalogenated straight-chain alkane with the hydroxyl group on 3,5-dibromophenol via nucleophilic substitution to form an ether bond, thereby obtaining intermediate A. The dihalogenated straight-chain alkane containing a halogen at the end is 1,4-dihalobutane, and the halogen atom thereof is Cl, Br or I; S3, dissolving the photosensitive dihydropyridine monomer and intermediate A in a polar organic solvent, and in the presence of a base, causing the hydroxyl group of the photosensitive dihydropyridine monomer to undergo a substitution reaction with the halogen group at the end of the halogenated linear alkyl group on intermediate A to obtain intermediate B; S4. Suzuki coupling reaction is performed on intermediate B and 4-hydroxymethylphenylboronic acid to finally obtain a novel hydroxyl-containing dihydropyridine photosensitizer, the molecular structure of which is as follows: 。 2. The method for synthesizing the novel hydroxyl-containing dihydropyridine photosensitizer according to claim 1, wherein: In step S3: intermediate A is dissolved in a polar organic solvent, and a photosensitive dihydropyridine monomer is added to the solution in a reaction environment in the presence of a base. The hydroxyl group of the photosensitive dihydropyridine monomer reacts with the halogen in intermediate A through nucleophilic substitution to form an ether bond, thereby obtaining intermediate B.

3. The method for synthesizing the novel hydroxyl-containing dihydropyridine photosensitizer according to claim 1, wherein: In step S4, intermediate B and 4-hydroxymethylphenylboronic acid are added to a polar organic solvent, and a catalytic amount of tetrakis(triphenylphosphine)palladium is added. The mixture is stirred and refluxed under an inert atmosphere in the presence of a base to obtain a novel hydroxyl-containing dihydropyridine photosensitizer.

4. The method for synthesizing the novel hydroxyl-containing dihydropyridine photosensitizer according to any one of claims 1 to 3, characterized in that: The polar organic solvent is selected from at least one of methanol, ethanol, tetrahydrofuran, chloroform, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

5. The method for synthesizing the novel hydroxyl-containing dihydropyridine photosensitizer according to any one of claims 1 to 3, characterized in that: The base is selected from at least one of lithium carbonate, potassium carbonate, sodium carbonate, rubidium carbonate, cesium carbonate, beryllium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, and barium carbonate.

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