Polylipoic acid modified naphthopyran compound as well as preparation method and application thereof

Abstract

The invention discloses a polylipoic acid modified naphthopyran compound, the structural general formula of which is selected from one of the following structures: the polylipoic acid modified naphthopyran compound provided by the invention is modified by a plurality of lipoic acids, so that the material compound not only has excellent photochromic performance of traditional naphthopyran, but also has excellent photochromic performance of the traditional naphthopyran; and the target product has plasticity, stretchability and scratch self-repairing performance. Therefore, the application range of naphthopyran is further expanded, an organic photochromic functional material with richer performance is developed and obtained, and market requirements are better met.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials, and in particular relates to a polylipoic acid-modified naphthopyran compound and a preparation method and application thereof. Background Art

[0002] Organic photochromic functional materials have shown tremendous application and research value in optical devices, optical lenses, optical actuators, molecular switches, fluorescent sensors, anti-counterfeiting and decorative materials, and optical information storage. Among the numerous organic photochromic materials, thermoreversible (T-type) photochromic compounds are particularly attractive and promising photoresponsive compounds due to their potential applications in color-changing mirrors, anti-counterfeiting, decoration, and dynamic holographic materials. Naphthopyran compounds are an important class of thermoreversible (T-type) photochromic materials. Their fast photoresponsiveness and low background color have attracted widespread attention from researchers and the market. They have broad application potential in various color-changing materials, anti-counterfeiting devices, and multi-color decorations. However, their practical applications are limited by unsatisfactory fatigue resistance and fading speed, necessitating further research and development. On the other hand, lipoic acid (Thioctic acid) is a naturally occurring small molecule that is an essential coenzyme for aerobic metabolism in animals. It is derived from readily available, renewable biomass resources and is naturally non-toxic. This compound possesses two dynamic chemical bonds: covalent disulfide bonds and non-covalent hydrogen bonds, giving it enormous potential for polymer preparation and application. Furthermore, at the melting temperature of lipoic acid, dynamic disulfide-SS exchange occurs, and the disulfide bonds containing the five-membered ring undergo thermally induced ring-opening polymerization, forming a linear, covalently bonded molecular backbone that exists in a fluid form. Upon cooling, the carboxyl side chains, dimerized by non-covalent hydrogen bonds, effectively crosslink to form linear polymers, resulting in a transparent polymer with excellent properties. This unique molecular structure also makes it a promising candidate for self-healing functional materials. Self-healing supramolecular materials are a rapidly developing class of intelligent materials. Their diverse functionality is closely related to numerous sectors of the national economy, making them a focus of renewed international competition. Summary of the Invention

[0003] The first object of the present invention is to provide a polylipoic acid-modified naphthopyran compound.

[0004] The second object of the present invention is to provide a method for preparing the polylipoic acid-modified naphthopyran compound.

[0005] The third object of the present invention is to provide a use of the polylipoic acid-modified naphthopyran compound in the preparation of organic functional materials.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect of the present invention, a polylipoic acid-modified naphthopyran compound is provided, the general structural formula of which is selected from one of the following structures:

[0008] in,

[0009] X1 is selected from O, NH;

[0010] R1 is selected from hydrogen, halogen (fluorine, chlorine, bromine, iodine);

[0011] R2 is selected from hydrogen, halogen (fluorine, chlorine, bromine, iodine);

[0012] R3 is selected from hydrogen;

[0013] R4 is selected from hydrogen, ;

[0014] R5 is selected from hydrogen, ;

[0015] R4 and R5 are not hydrogen at the same time;

[0016] Y1 is selected from O, NH;

[0017] R6 is selected from hydrogen;

[0018] R7 is selected from hydrogen;

[0019] X2 is selected from O, NH;

[0020] R8 is selected from hydrogen, halogen (fluorine, chlorine, bromine, iodine);

[0021] R9 is selected from hydrogen, halogen (fluorine, chlorine, bromine, iodine);

[0022] Y2 is selected from O, NH;

[0023] X3 is selected from O, NH;

[0024] R 10 Selected from hydrogen, halogen (fluorine, chlorine, bromine, iodine);

[0025] R 11 Selected from hydrogen, halogen (fluorine, chlorine, bromine, iodine);

[0026] Y3 is selected from O, NH;

[0027] X4 is selected from O, NH;

[0028] R 12 Selected from hydrogen, halogen (fluorine, chlorine, bromine, iodine);

[0029] R 13 Selected from hydrogen, halogen (fluorine, chlorine, bromine, iodine);

[0030] Y4 is selected from O and NH.

[0031] Most preferably, the polylipoic acid-modified naphthopyran compound is selected from one of the following structures:

[0032]

[0033] The second aspect of the present invention provides a method for preparing the polylipoic acid-modified naphthopyran compound, comprising the following steps:

[0034] Dissolve compound a and compound b in a solvent at a molar ratio of 0.5 to 2:1 (preferably 0.75:1, 0.8:1, 1.1:1, 1.25:1, 1.33:1, 1.4:1, and 1.5:1), add a catalytic amount of a catalyst, and heat under reflux under nitrogen protection to react for 1 to 12 hours (preferably 6.5, 6, 7, 8, or 9 hours) to obtain the polylipoic acid-modified naphthopyran compound;

[0035] or,

[0036] Dissolve compound a and compound b in a solvent at a molar ratio of 0.5 to 2:1 (preferably 0.75:1, 0.8:1, 1.1:1, 1.25:1, 1.33:1, 1.4:1, 1.5:1), add a catalytic amount of a catalyst, and heat under reflux in the dark under nitrogen protection for 1 to 12 hours (preferably 6.5, 6, 7, 8, 9 hours) to obtain an intermediate;

[0037] Under inert gas protection and light-proof conditions, the intermediate prepared above is dissolved in a solvent, a halogenating agent is added, the molar ratio of the halogenating agent to the intermediate is 1:1, and the mixture is stirred and heated to reflux for 1 to 12 hours (preferably 6.5, 6, 7, 8, or 9 hours) to obtain the polylipoic acid-modified naphthopyran compound;

[0038] The compound a is selected from one of the following structures:

[0039] The compound b is selected from one of the following structures:

[0040] The catalyst is selected from p-toluenesulfonic acid and cationic resin (D001 macroporous strong acid styrene cationic resin);

[0041] The halogenating agent is selected from N-chlorosuccinimide and N-bromosuccinimide.

[0042] The solvent is selected from tetrahydrofuran, toluene, dichloromethane, and DMSO.

[0043] The third aspect of the present invention provides a use of the polylipoic acid-modified naphthopyran compound in the preparation of organic functional materials.

[0044] The fourth aspect of the present invention provides a use of the polylipoic acid-modified naphthopyran compound in the preparation of photochromic materials, photoelectric molecular switches, high-density optical information storage media, photochromic glasses, photochromic films, and anti-counterfeiting materials.

[0045] The fifth aspect of the present invention provides a use of the polylipoic acid-modified naphthopyran compound in the preparation of a product with scratch self-repairing function.

[0046] Due to the adoption of the above technical solution, the present invention has the following advantages and beneficial effects:

[0047] The polylipoic acid-modified naphthopyran compounds provided by the present invention are easy to form into films and perform material processing due to the cross-linking polymerization and self-repairing structure of the lipoic acid bonding. Studies have shown that such compounds can quickly switch between different on-off ring states under the stimulation of light and exhibit scratch self-repairing function. They can be used in the fields of optical lenses, color-changing powders, color displays, anti-counterfeiting materials, etc.

[0048] The polylipoic acid-modified naphthopyran compound provided by the present invention has rapid reversibility and scratch self-repairing function.

[0049] The polylipoic acid-modified naphthopyran compounds provided by the present invention bond naphthopyran color-changing functional molecules to polylipoic acid molecules and greatly shorten the fading time through 1,2-position halogenation. At the same time, the natural non-toxicity and reversible cross-linking characteristics of lipoic acid are utilized to improve the film-forming quality and color-changing efficiency of the molecules, which is more conducive to the practical application of molecular devices and materials.

[0050] The color changing and switching method of the polylipoic acid-modified naphthopyran compound provided by the present invention is as follows: at room temperature, the polylipoic acid-modified naphthopyran compound prepared in an embodiment of the present invention is dissolved in an organic solvent at a certain concentration M1, and the solution is irradiated with light of a wavelength of λ1 nanometers for h1 hour, and the solution gradually changes from colorless to colored; then irradiated with light of a wavelength of λ2 nanometers for h2 hours, and the solution fades from colored back to colorless; the polylipoic acid-modified naphthopyran compound prepared in an embodiment of the present invention can quickly switch between different switch ring states and colors under the stimulation of light and heat. Wherein, the organic solvent is any one of tetrahydrofuran, ethanol, dichloromethane, methanol, and chloroform. M1 is 10 -6 -10- 3 mol / L, λ1 was 200-400 nm, λ2 was 400-650 nm, and h1 and h2 were both 0-2 h.

[0051] The polylipoic acid-modified naphthopyran compounds provided by the present invention are modified with multiple lipoic acids. In addition to the excellent photochromic properties of traditional naphthopyrans, these materials also exhibit plasticity, stretchability, and scratch self-healing properties. This further expands the application range of naphthopyrans and allows the development of organic photochromic functional materials with richer properties to better meet market demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram of fatigue test results under alternating ultraviolet and visible light irradiation. DETAILED DESCRIPTION

[0053] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0054] Example 1

[0055] Compound 1b (40 mmol, 26.64 g) (Synthesis and photochromic properties of some fluorine-containing naphthopyrans[J], Dyes and Pigments, 2002, 54: 79-93) and compound 1a (60 mmol, 20.86 g) were added to a reaction flask. Then, 150 mL of toluene dried over anhydrous sodium sulfate was added. After stirring and dissolving, p-toluenesulfonic acid (12 mmol, 2 g) was added. The mixture was heated under reflux under nitrogen and in the dark for 6 hours. The reaction progress was monitored by thin-layer chromatography. After completion, the white solid was filtered off, and the mother liquor was extracted three times with ethyl acetate. The organic phases were combined and dried over anhydrous Na₂SO₄. The solvent was removed, and the resulting solid was separated and purified by column chromatography (PE:EA = 6:1, V / V). 25.8 g of polylipoic acid-modified naphthopyran compound Ia was obtained in a 68% yield. 1H NMR (400MHz, CDCl3, ppm): δ = 7.66 (d, J =7.6, 1H,naphthalene-H), 7.58 (d, J =7.6,1H, naphthalene-H), 7.45 (s,1 H, naphthalene-H), 7.18-7.09 (m,6H,naphthalene,benzene-H),7.02 (d, J =7.5, 4H, benzene-H), 6.56 (d, J =9.2, 1H,-CH=C-), 6.38(d, J =9.2, 1H,-C=CH-), 2.67-2.52 (m, 9H), 2.26-2.20 (m, 6H), 1.98-1.85 (m,6H), 1.60-1.53 ​​(m, 12H), 1.33-1.20 (m, 6H). HRMS [C 49 H 54 O7S6], calculated value: 946.2194; found value: 946.2118.

[0056] Example 2

[0057] Compound 2a (50 mmol, 17.38 g) and compound 2b (40 mmol, 24.6 g) were added to a reaction flask, followed by 150 mL of dry toluene. After stirring to dissolve, a catalytic amount of D001 macroporous, strongly acidic styrene-based cationic resin was added. Under nitrogen, the mixture was heated under reflux and protected from light for 7 hours. The reaction progress was monitored by thin-layer chromatography. After completion, the white solid was filtered off, and the mother liquor was extracted three times with ethyl acetate. The organic phases were combined and dried over anhydrous Na₂SO₄. The solvent was then removed by rotary evaporation. The resulting solid was separated and purified by column chromatography (PE:EA = 6:1, V / V) to obtain 22.7 g of polylipoic acid-modified naphthopyran compound Ib in a 60% yield. 1H NMR (400 MHz, CDCl3, ppm): δ = 8.15 (s, 3H, -NH), 7.42 (d, J =7.5, 1H, naphthalene-H), 7.35 (d, J =8.2, 1H, naphthalene-H), 7.57 (d, J =7.6, 4H, benzene-H), 7.18 (d, J =7.6, 4H, benzene-H), 6.92 -6.75(m, 3H, naphthalene-H), 6.56 (d, J =9.2, 1H,-CH=C-), 6.37 (d, J =9.1, 1H,-C=CH-), 2.66-2.51 (m, 9H), 2.25-2.21 (m, 6H), 1.99-1.84 (m, 6H), 1.61-1.52 (m,12H), 1.32-1.27 (m, 6H). HRMS [C 49 H 57 N3O4S6], calculated: 943.2673; found: 943.2645.

[0058] Example 3

[0059] Compound 1b (50 mmol, 17.38 g) and compound 2a (55 mmol, 33.93 g) were added to a reaction flask. Then, 150 mL of dichloromethane dried over anhydrous sodium sulfate was added. After stirring to dissolve, a catalytic amount of p-toluenesulfonic acid was added. Under nitrogen, the mixture was heated under reflux and protected from light for 8 hours. The reaction progress was monitored by thin-layer chromatography. After completion, the white solid was filtered off, and the mother liquor was extracted three times with ethyl acetate. The organic phases were combined and dried over anhydrous MgSO₄. The solvent was then removed by rotary evaporation. The resulting solid was separated and purified by column chromatography (PE:EA = 6:1, V / V) to obtain 34.1 g of polylipoic acid-modified naphthopyran compound Ic in a 72% yield. 1H NMR (400 MHz, CDCl3, ppm): δ = 8.21(s, 1H, -NH), 7.59(d, J =7.6, 4H, benzene-H), 7.41 (d, J =7.5, 1H, naphthalene-H), 7.36(d, J =8.1, 1H, naphthalene-H), 7.14 (d, J =7.7, 4H, benzene-H), 6.91-6.75 (m, 3H,naphthalene-H), 6.53 (d, J =9.3, 1H, -CH=C-), 6.38 (d, J =9.1, 1H, -C=CH-), 2.62-2.57 (m, 9H), 2.29-2.20 (m, 6H), 1.97-1.85(m, 6H), 1.60-1.55 (m, 12H),1.35-1.22 (m, 6H). HRMS [C 49 H 55 NO6S6], calculated: 945.2354; found: 945.2366.

[0060] Example 4

[0061] Compound 1b (60 mmol, 37.01 g) and compound 1a (80 mmol, 27.88 g) were added to a reaction flask. 150 mL of toluene dried over anhydrous sodium sulfate was added, stirred, and dissolved. A catalytic amount of p-toluenesulfonic acid was then added. Under nitrogen, the mixture was heated under reflux in the dark for 6 hours. The reaction progress was monitored by thin-layer chromatography. After completion, the white solid was filtered off, and the mother liquor was extracted three times with ethyl acetate. The organic phases were combined and dried over anhydrous Na₂SO₄. The solvent was then removed by rotary evaporation. The resulting solid was isolated and purified by column chromatography (PE:EA = 6:1) to obtain 39.22 g of the intermediate in a 69% yield.

[0062] Under inert gas protection and light-shielding conditions, the intermediate prepared above (41.4 mmol) was completely dissolved in 150 mL of dichloromethane, and N-chlorosuccinimide (41.4 mmol, 5.53 g) was added. The mixture was stirred and heated to reflux for 6 hours. After the reaction was completed, it was cooled to room temperature. After extraction, water washing, drying, concentration, and column chromatography (PE:EA=5:1), 16.88 g of polylipoic acid-modified naphthopyran compound Ie was obtained with a yield of 41.6%. 1H NMR (400 MHz, CDCl3,ppm): δ = 7.17 (d, J =7.4, 1H, naphthalene-H), 7.64 (d, J =7.5, 1H, naphthalene-H), 7.55 (d, J =8.2, 1H, naphthalene-H), 7.48 (s,1H, naphthalene-H), 7.15 (d, J =8.2, 1H, naphthalene-H), 7.12 (d, J =7.7, 4H, benzene-H), 7.01 (d, J =7.9, 4H, benzene-H), 6.77 (s, 1H,-CH=C-), 2.63-2.57 (m, 9H), 2.25-2.21(m, 6H), 1.98-1.79 (m, 6H), 1.63-1.51 (m, 12H), 1.36-1.24 (m, 6H). HRMS[C 49 H 53 ClO7S6], calculated: 980.1804; found: 980.1812.

[0063] Example 5

[0064] Compound 1b (40 mmol, 26.64 g) and compound 1a (50 mmol, 17.42 g) were added to a reaction flask. 150 mL of dichloromethane dried over anhydrous sodium sulfate was added. After stirring to dissolve, D001 macroporous strongly acidic styrene cationic resin (Beijing Inokai Technology Co., Ltd.) was added. Under nitrogen, the mixture was heated under reflux in the dark for 6 hours. The reaction progress was monitored by thin-layer chromatography. After completion, the white solid was filtered off, and the mother liquor was extracted three times with ethyl acetate. The organic phases were combined and dried over anhydrous Na₂SO₄. The solvent was then removed by rotary evaporation. The resulting solid was separated and purified by column chromatography (PE:EA = 6:1, V / V) to obtain 25.77 g of the intermediate in a 68% yield.

[0065] Under inert gas protection and light-shielding conditions, the intermediate prepared above (27 mmol, 25.77 g) was dissolved in 100 mL of dichloromethane, and N-bromosuccinimide (27 mmol, 4.8 g) was added. The mixture was stirred and heated to reflux for 9 hours. After the reaction was completed, it was cooled to room temperature. After extraction, washing with water, drying, concentration, and column chromatography (PE:EA=5:1), 12.47 g of polylipoic acid-modified naphthopyran compound Ig was obtained with a yield of 45%. 1H NMR (400 MHz, CDCl3, ppm): δ =7.65(d, J =7.5, 1H, naphthalene-H), 7.54(d, J =8.2, 1H, naphthalene-H), 7.47(s,1H, naphthalene-H), 7.16-7.11 (m, 6H, naphthalene-H, benzene-H), 7.02 (d,J =7.9, 4H, benzene-H), 6.38(s, 1H,-CH=C-), 2.62-2.56 (m, 9H), 2.24-2.16 (m,6H), 1.98-1.79 (m, 6H), 1.63-1.51 (m, 12H), 1.34-1.22 (m, 6H). HRMS[C 49 H 53 BrO7S6] Calculated: 1024.1299; Found: 1024.12919.

[0066] Example 6

[0067] Compound 1b (40 mmol, 26.64 g) and compound 6a (60 mmol, 20.9 g) were added to a three-necked flask. 150 mL of dried toluene was then added, stirred, and dissolved. A catalytic amount of p-toluenesulfonic acid was then added. Under nitrogen, the mixture was heated under reflux and protected from light for 7 hours. The reaction progress was monitored by thin-layer chromatography. After completion, the white solid was filtered off, and the mother liquor was extracted three times with ethyl acetate. The organic phases were combined and dried over anhydrous MgSO₄. The solvent was then removed by rotary evaporation. The resulting solid was separated and purified by column chromatography (PE:EA = 6:1), yielding 22.7 g of polylipoic acid-modified naphthopyran compound Ij in a 60% yield. 1H NMR(400 MHz, CDCl3, ppm): δ = 7.64 (d, J =7.4, 1H, naphthalene-H), 7.57 (d, J =7.6, 1H, naphthalene-H), 7.41 (s,1 H, naphthalene-H), 7.19-7.06 (m, 6H,naphthalene, benzene-H),6.97 (d, J =7.5, 4H, benzene-H), 6.58 (d, J =9.1,1H,-CH=C-), 6.39 (d, J =9.1, 1H,-C=CH-), 2.66-2.50 (m, 9H), 2.28-2.20 (m,6H), 1.98-1.85 (m, 6H), 1.61-1.54 (m, 12H), 1.34-1.22 (m, 6H). HRMS[C 49 H 54 O7S6] Calculated: 946.2194; Found: 946.2185.

[0068] Example 7

[0069] In a 200 mL three-necked flask, compound 1b (50 mmol, 17.38 g) and compound 7a (70 mmol, 24.39 g) were added sequentially. 150 mL of toluene dried over anhydrous sodium sulfate was added, stirred, and dissolved. A catalytic amount of p-toluenesulfonic acid was then added. Under nitrogen, the mixture was heated under reflux in the dark for 6.5 hours. The reaction progress was monitored by thin-layer chromatography. After completion, the white solid was filtered off, and the mother liquor was extracted three times with ethyl acetate. The organic phases were combined and dried over anhydrous Na₂SO₄. The solvent was then removed by rotary evaporation. The resulting solid was separated and purified by column chromatography (PE:EA = 6:1, V / V) to obtain 30.79 g of polylipoic acid-modified naphthopyran compound Il in a 65% yield. 1H NMR (400MHz, CDCl3, ppm): δ=7.58-7.33 (m, 3H,naphthalene-H), 7.17 (m, 5H, benzene-H, naphthalene-H), 7.08 (d, J =7.5, 4H,benzene-H), 6.91 (d, J =7.7, 1H,naphthalene-H), 6.57 (d, J =9.5, 1H,-CH=C-), 6.34 (d, J =9.6, 1H,-C=CH-), 2.74-2.49 (m, 9H), 2.32-2.12 (m, 6H), 1.91-1.75(m, 6H), 1.63-1.44 (m, 12H), 1.32-1.24 (m, 6H). HRMS [C 49 H 54 O7S6] Calculated value: 946.2194; Found: 946.2198.

[0070] Example 8

[0071] Compound 1a (80 mmol, 27.88 g) and compound 8b (100 mmol, 61.69 g) were added to a reaction flask. 200 mL of tetrahydrofuran, dried over anhydrous sodium sulfate, was added. After stirring to dissolve, a catalytic amount of p-toluenesulfonic acid was added. Under nitrogen, the mixture was heated under reflux in the dark for 9 hours. The reaction progress was monitored by thin-layer chromatography. After completion, the white solid was filtered off, and the mother liquor was extracted three times with ethyl acetate. The organic phases were combined and dried over anhydrous Na₂SO₄. The solvent was then removed by rotary evaporation. The resulting solid was isolated and purified by column chromatography (PE:EA = 6:1) to yield 42.46 g of the intermediate.

[0072] Under inert gas protection and light-shielding conditions, the intermediate prepared above (44 mmol) was completely dissolved in 150 mL of tetrahydrofuran solvent, and N-chlorosuccinimide (44 mmol, 5.88 g) was added. The mixture was stirred and heated to reflux for 6.5 hours. After the reaction was completed, it was cooled to room temperature. After extraction, washing, drying, concentration, and column chromatography, 17.7 g of polylipoic acid-modified naphthopyran compound Im was obtained with a yield of 41%. 1H NMR (400 MHz, CDCl3, ppm): δ = 7.65 (d,J =7.5, 1H, naphthalene-H), 7.55 (d, J =8.3, 1H, naphthalene-H), 7.45 (s,1H,naphthalene-H), 7.02-7.17 (m, 10H, naphthalene-H, benzene-H), 6.79 (s, 1H,-CH=C-), 2.61-2.55 (m, 9H), 2.29-2.20 (m, 6H), 1.97-1.79 (m, 6H), 1.65-1.52 (m,12H), 1.20-1.39 (m, 6H). HRMS [C 49 H 53 ClO7S6] Calculated: 980.1804; Found: 980.1815.

[0073] Example 9

[0074] Compound 9a (60 mmol, 20.85 g) and compound 1b (80 mmol, 53.28 g) were added sequentially to a three-necked flask. 150 mL of tetrahydrofuran, dried over anhydrous sodium sulfate, was added and stirred to dissolve. A catalytic amount of p-toluenesulfonic acid was then added. Under nitrogen, the mixture was heated under reflux in the dark for 8 hours. The reaction progress was monitored by thin-layer chromatography. After completion, the white solid was filtered off, and the mother liquor was extracted three times with ethyl acetate. The organic phases were combined and dried over anhydrous Na₂SO₄. The solvent was then removed by rotary evaporation. The resulting solid was isolated and purified by column chromatography (PE:EA = 5:1) to yield 34.72 g of the intermediate.

[0075] Under inert gas protection and light-shielding conditions, the intermediate prepared above (36 mmol, 34.72 g) was dissolved in 100 mL of tetrahydrofuran, and N-bromosuccinimide (36 mmol, 6.41 g) was added. The mixture was stirred and heated to reflux for 6 hours. After the reaction was completed, it was cooled to room temperature. After extraction, washing with water, drying, concentration, and column chromatography, 16.57 g of polylipoic acid-modified naphthopyran compound Ip was obtained with a yield of 45%. 1H NMR (400 MHz, CDCl3, ppm): δ = 8.11(s, 1H,-NH), 7.49 (d, J =7.1, 1H, naphthalene-H), 7.36 (d, J =7.5, 1H, naphthalene-H), 7.19 (d, J =7.4, 4H, benzene-H), 7.02 (d, J =7.6, 4H, benzene-H), 6.91(s, 1H, -CH=C-), 6.66-6.75 (m, 3H, naphthalene-H), 2.60-2.47 (m, 9H), 2.29-2.18 (m, 6H), 1.98-1.81(m, 6H), 1.62-1.54 (m, 12H), 1.23-1.37 (m, 6H). HRMS[C 49 H 54 BrNO6S6] calculated: 1023.1459; found: 1023.1447.

[0076] The polylipoic acid-modified naphthopyran compounds prepared by the present invention have good photochromic properties. The color change principle is similar. The following uses compound Ia as an example to illustrate the photochromic change of the compound prepared by the present invention, which leads to structural changes. The structural changes are shown below:

[0077] At room temperature, compound Ia was prepared at a concentration of 10 -5 When a mol / L tetrahydrofuran solution of the substance is irradiated with ultraviolet light at a wavelength of 254 nanometers for 3 minutes, the solution rapidly changes from colorless to colored and reaches a photostable state. Further irradiation with visible light at a wavelength of 500 nanometers for 5 minutes causes the solution to fade from colored back to its original colorless state. Alternatively, if the colored solution is kept in a dark place for 30 minutes, the solution will fade from colored back to its original colorless state. This reversible color change process from colorless to colored can be repeated multiple times.

[0078] The compound of the present invention has high fatigue resistance. For example, after 100 cycles of alternating irradiation of ultraviolet and visible light, the maximum absorption at 475 nm at the monitoring point can recover to a value close to the initial value (e.g. Figure 1 As shown, Figure 1The figure is a schematic diagram of fatigue resistance test results under alternating UV and visible light irradiation. After 3 seconds of UV irradiation, a noticeable color change was observed, demonstrating excellent photosensitivity. Furthermore, a film made by mixing the compound prepared in this invention with polymethyl methacrylate (PMMA) was able to self-heal after being scratched within 10 minutes, a property not possessed by currently reported naphthopyran photochromic compounds.

[0079] Film preparation method: Compound Ia prepared in the present invention and polymethyl methacrylate (PMMA) at a mass ratio of 1:100 were dissolved in tetrahydrofuran, and the mixture was evenly dropped onto a smooth and clean glass slide. The mixture was placed in a fume hood at room temperature in the dark to allow the solvent to evaporate naturally to obtain a film.

[0080] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with this patent can make slight changes or modifications to equivalent embodiments using the above technical content without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the solution of the present invention.

Claims

1. A polylipoic acid-modified naphthopyran compound, characterized in that: The general structural formula is selected from one of the following structures: ； in, X1 is selected from O, NH; R1 is selected from hydrogen, halogen; R2 is selected from hydrogen, halogen; R3 is selected from hydrogen; R4 is selected from hydrogen, ; R5 is selected from hydrogen, ; R4 and R5 are not hydrogen at the same time; Y1 is selected from O, NH; R6 is selected from hydrogen; R7 is selected from hydrogen; X2 is selected from O, NH; R8 is selected from hydrogen, halogen; R9 is selected from hydrogen, halogen; Y2 is selected from O, NH; X3 is selected from O, NH; R 10 is selected from hydrogen and halogen; R 11 is selected from hydrogen and halogen; Y3 is selected from O, NH; X4 is selected from O, NH; R 12 is selected from hydrogen and halogen; R 13 is selected from hydrogen and halogen; Y4 is selected from O and NH.

2. The polylipoic acid-modified naphthopyran compound according to claim 1, wherein The polylipoic acid-modified naphthopyran compound is selected from one of the following structures: ； 。 3. A method for preparing the polylipoic acid-modified naphthopyran compound according to claim 1 or 2, characterized in that: The following steps are involved: Dissolving compound a and compound b in a molar ratio of 0.5 to 2:1 in a solvent, adding a catalytic amount of a catalyst, and heating under reflux in the dark for a reaction of 1 to 12 hours under nitrogen protection to obtain the polylipoic acid-modified naphthopyran compound; or, Dissolve compound a and compound b in a solvent at a molar ratio of 0.5 to 2:1, add a catalytic amount of a catalyst, and heat under reflux in the dark under nitrogen protection for 1 to 12 hours to obtain an intermediate; Under inert gas protection and light-proof conditions, the intermediate prepared above is dissolved in a solvent, a halogenating agent is added, the molar ratio of the halogenating agent to the intermediate is 1:1, and the mixture is stirred and heated to reflux for 1 to 12 hours to obtain the polylipoic acid-modified naphthopyran compound; The compound a is selected from one of the following structures: ； The compound b is selected from one of the following structures: ； The catalyst is selected from p-toluenesulfonic acid and cationic resin; The halogenating agent is selected from N-chlorosuccinimide and N-bromosuccinimide.

4. The method for preparing the polylipoic acid-modified naphthopyran compound according to claim 3, wherein: The solvent is selected from tetrahydrofuran, toluene, dichloromethane, and DMSO.

5. Use of the polylipoic acid-modified naphthopyran compound according to claim 1 or 2 in the preparation of organic functional materials.

6. Use of the polylipoic acid-modified naphthopyran compound according to claim 1 or 2 in the preparation of photochromic materials, photoelectric molecular switches, high-density optical information storage media, color-changing glasses, color-changing films, and anti-counterfeiting materials.

7. Use of the polylipoic acid-modified naphthopyran compound according to claim 1 or 2 in the preparation of a product with scratch self-repairing function.

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