Novel hydroxyl-containing dihydropyridine photosensitizer as well as preparation method and application thereof

Abstract

The invention relates to the technical field of synthesis of photosensitive organic compounds, and discloses a novel hydroxyl-containing dihydropyridine photosensitizer and a preparation method and application thereof.The method comprises the steps that 5-hydroxy-2-nitrobenzaldehyde serves as an initial raw material and reacts with 3-aminocrotonic acid methyl benzoate under the catalytic action of trifluoroformic acid, and a reaction product is obtained; precipitating, filtering and recrystallizing the product to obtain a photosensitive dihydropyridine monomer; the preparation method comprises the following steps: by taking 3, 5-dibromophenol as an initial raw material, introducing halogenated straight-chain alkyl of which the tail end is halogen into a hydroxyl position on the 3, 5-dibromophenol; dissolving a photosensitive dihydropyridine monomer and the intermediate A, and carrying out substitution reaction under the action of alkali to prepare an intermediate B; and carrying out Suzuki coupling reaction on the intermediate B and 4-hydroxymethyl phenylboronic acid to finally obtain the novel dihydropyridine photosensitizer containing hydroxyl. The novel hydroxyl-containing dihydropyridine photosensitizer (DHPDO) is good in compound stability, the preparation process is simple and convenient, the stability of an intermediate product is high, and after-treatment purification is low in toxicity and harmless.

Description

Technical Field

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

[0002] In today's digitally connected world, ensuring the secure transmission of information has become a top priority. However, the ubiquity of light poses a major challenge to materials with a single stimulus response, 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 easy physical shape adjustment.

[0003] Polyurethane (PU) is one of the viable materials due to its excellent controllability. Researchers can use PU as a host matrix and introduce various functional parts to prepare films with different applications. The integration of various hard and soft segments in polyurethane 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 stimulus response mechanism. For example, the addition of soft segments such as polycaprolactone (PCL), castor oil (CO), and polytetramethylene ether glycol (PTMEG) can endow PU with shape memory properties. The tailored properties make PU an ideal candidate for information encryption. To endow polymers with dynamic and reversible properties, researchers have introduced specific dynamic parts or substances into the polymer network. Examples include disulfide bonds (-SS-), oxime bonds, urea bonds, and dynamic covalent bonds. This unique feature expands the applicability of PU beyond encryption, including adaptive smart windows and high-strength adhesive materials. The versatility of polyurethane highlights its strategic importance, not only helping to protect sensitive information but also helping to promote the development of diversified fields. Therefore, photosensitive polyurethane can be used as an excellent choice for pattern preparation in anti-counterfeiting labels. Photosensitive polyurethane can be produced by polycondensation reaction of photosensitive diol and active isocyanate, but the preparation efficiency of photosensitive diol in the prior art is low, and the prepared photosensitive diol has poor stability and is not easy to store at room temperature and pressure, which makes it impossible to prepare photosensitive diol in large quantities. Therefore, in order to solve the problem of poor stability of photosensitive diol and the shortcomings of low preparation efficiency caused by low conversion rate of intermediate products in its preparation process, it is urgent to improve the prior art.

[0004] The present invention utilizes the added photosensitive functional unit of polyurethane to achieve light response, thereby realizing the special application of polyurethane in light encryption, which provides further innovative value for the design and implementation of multifunctionality in the field of information encryption. Summary of the invention

[0005] In order to solve the above shortcomings in the prior art, the present invention aims to provide a method for preparing photosensitizing functional biphenyl diol, so as to achieve a simple preparation method, high yield, and strong stability of the intermediate product. The prepared hydroxyl-containing dihydropyridine novel 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 object, on the one hand, 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 the starting material, reacting with 3-aminocrotonylbenzoic acid methyl ester in an anhydrous polar organic solvent at a reaction temperature of 0 to 10° C. under the catalysis of trifluoromethane, the product after the reaction 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, introducing a halogenated straight-chain alkyl group with a halogen terminal at the hydroxyl position of 3,5-dibromophenol to obtain an intermediate A;

[0012] S3, dissolving the photosensitive dihydropyridine monomer and intermediate A in a polar organic solvent, and under the action of a base, the hydroxyl group of the photosensitive dihydropyridine monomer and the halogen group at the end of the halogenated straight-chain alkyl group on the intermediate A undergo a substitution reaction to obtain intermediate B;

[0013] S4. The intermediate B is subjected to 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, and the halogen at one end of the dihalogenated straight-chain alkane is reacted with the hydroxyl group on 3,5-dibromophenol through nucleophilic substitution to form an ether bond, thereby obtaining intermediate A.

[0015] As a further preferred technical solution of the present invention, the dihalogenated straight-chain alkane containing 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 reaction 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 photosensitizing 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 strong stability of the intermediate product, and is low-toxic and harmless after post-treatment 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 have low production cost. The present invention is the first to synthesize the novel hydroxyl-containing dihydropyridine photosensitizer, and it can be applied to the synthesis of photosensitive polyurethane to form a photosensitivity polyurethane with a rigid main chain and a certain flexibility of the side chain. Due to the presence of photosensitive groups, its application as a functional molecule is greatly expanded, and it is expected that the polyurethane can be applied to information storage and anti-counterfeiting applications. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0025] Figure 1 The 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.

[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 in conjunction with the embodiments. DETAILED DESCRIPTION

[0032] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

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

[0034] The novel hydroxyl-containing dihydropyridine photosensitizer (DHPDO) provided by the present invention has the following molecular structure:

[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] Embodiment 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 uniform solution. Then, add an appropriate amount of trifluoroacetic acid (27 ml) (3.5 mmol, 3 eq) while stirring in an ice bath at 0°C;

[0041] A2. Dissolve 34.54 g (30 mmol, 3 eq) of 3-amino methyl crotonate in 150 ml of anhydrous ethanol, gradually add anhydrous ethanol solution (150 ml) of 3-amino methyl crotonate 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 completed, add a large amount of deionized water to precipitate, filter, heat and dissolve the intercepted material with a small amount of ethanol, and recrystallize to obtain the purified target product NDHP, which is weighed after drying (yield is 70%). The structure of NDHP (DMSO-d6) is shown in Figure 3 of 1 HNMR characterization confirmed.

[0043] (2) Synthesis of intermediate A

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

[0045] B2. After the reaction was completed, the reaction solution was cooled to room temperature, washed with petroleum ether, and purified by silica gel column chromatography under reduced pressure to obtain a colorless transparent liquid intermediate A (x is Br) (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 refluxed and stirred for 36 h under an inert gas atmosphere;

[0048] C2. After the reaction was completed, the product was washed with petroleum ether and purified by silica gel column chromatography to obtain a light yellow solid intermediate B (x is Br) (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. Add tetrahydrofuran (100 mL) to a 500 mL flask to dissolve intermediate B (1 eq, 19.83 mmol) to obtain a uniform mixed solution, then add 2M K2CO3 aqueous solution (70 mL) and 4-hydroxymethylphenylboronic acid (5.71 g, 49.58 mmol), and then purge 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 to the above mixed solution, stir and reflux for 72h under an inert gas atmosphere;

[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 type of hydroxyl-containing dihydropyridine photosensitizer (DHPDO) was obtained (yield 76%). Its structure is Figure 6 of 1 The identification was confirmed by H NMR.

[0053] Embodiment 2:

[0054] This embodiment provides a method for preparing photosensitive polyurethane based on a novel photosensitizer containing hydroxyl dihydropyridine, which is 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 novel dihydropyridine photosensitizer monomer (DHPDO) (1 mmol) of the present invention 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 under ice bath conditions at 0°C and stir in an ice bath for 1.5 h;

[0058] (4) Inject 15 mmol of 1,4-dibutanol (BDO) dropwise under an ice bath at 0°C, then remove the ice bath, stir and react at room temperature for 12 h, heat and react at 40°C for 12 h, and heat and react at 60°C for 12 h, and finally obtain a photosensitive polyurethane solution;

[0059] (5) Spin-coat the photosensitive polyurethane solution onto 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 novel hydroxyl-containing dihydropyridine photosensitizer, characterized in that: Its molecular structure is as follows:

2. The method for synthesizing the novel hydroxyl-containing dihydropyridine photosensitizer according to claim 1, characterized in that: The following steps are involved: S1. Using 5-hydroxy-2-nitrobenzaldehyde as the starting material, reacting with 3-aminocrotonylbenzoic acid methyl ester in an anhydrous polar organic solvent at a reaction temperature of 0 to 10° C. under the catalysis of trifluoromethane, the product after the reaction is precipitated, filtered, and recrystallized to obtain a photosensitive dihydropyridine monomer having the following structural formula: S2, using 3,5-dibromophenol as a starting material, introducing a halogenated straight-chain alkyl group with a halogen terminal at the hydroxyl position of 3,5-dibromophenol to obtain an intermediate A; S3, dissolving the photosensitive dihydropyridine monomer and intermediate A in a polar organic solvent, and under the action of a base, the hydroxyl group of the photosensitive dihydropyridine monomer and the halogen group at the end of the halogenated straight-chain alkyl group on the intermediate A undergo a substitution reaction to obtain intermediate B; S4. The intermediate B is subjected to Suzuki coupling reaction with 4-hydroxymethylphenylboronic acid to finally obtain a novel hydroxyl-containing dihydropyridine photosensitizer.

3. The method for synthesizing the novel hydroxyl-containing dihydropyridine photosensitizer according to claim 2, characterized in that: 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, and the halogen at one end of the dihalogenated straight-chain alkane reacts with the hydroxyl group on 3,5-dibromophenol through nucleophilic substitution to form an ether bond, thereby obtaining intermediate A.

4. The method for synthesizing the novel hydroxyl-containing dihydropyridine photosensitizer according to claim 3, characterized in that: The dihalogenated straight-chain alkane containing a halogen atom at the terminal is 1,4-dihalobutane, and the halogen atom thereof is Cl, Br or I.

5. The method for synthesizing the novel hydroxyl-containing dihydropyridine photosensitizer according to claim 2, characterized in that: 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.

6. The method for synthesizing the novel hydroxyl-containing dihydropyridine photosensitizer according to claim 2, characterized in that: 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 in an inert atmosphere in a reaction environment in the presence of a base to obtain a novel hydroxyl-containing dihydropyridine photosensitizer.

7. The method for synthesizing the novel hydroxyl-containing dihydropyridine photosensitizer according to any one of claims 2 to 6, 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.

8. The method for synthesizing the novel hydroxyl-containing dihydropyridine photosensitizer according to any one of claims 2 to 6, 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.

9. Use of the novel hydroxyl-containing dihydropyridine photosensitizer according to claim 1 or the novel hydroxyl-containing dihydropyridine photosensitizer prepared by the method according to any one of claims 2 to 8 in the preparation of photosensitive polyurethane.

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