Azobenzene derivative with over-crowded structure as well as preparation method and application method of azobenzene derivative

Abstract

The invention discloses an azobenzene derivative with an over-crowded structure as well as a preparation method and an application method of the azobenzene derivative. Belongs to the technical field of azobenzene derivatives. According to the azobenzene derivative, azobenzene serves as a central unit, various functional group units are introduced to serve as branched chains, and various configurations such as a trans-cross state configuration and a trans-parallel state configuration based on an over-crowded state can be formed through the influence of the lengths, groups and the like of the branched chains. The azobenzene derivative can realize mutual conversion among structures through solvochromism, mechanochromism, gasochromism, thermochromism and the like, has the potential of realizing functions similar to those of a molecular machine, and can be applied as novel ink or a coloring agent and an intelligent color changing agent or a color developing agent.

Description

Technical Field

[0001] The present invention belongs to the technical field of azobenzene derivatives, and particularly relates to azobenzene derivatives with an overcrowded structure and their preparation and application methods. Background Art

[0002] Azobenzene has photoisomerization, and it can be transformed from the more stable E-form configuration to the Z-form configuration under light irradiation, undergoing E / Z isomerization. Since the discovery of this photoisomerization property, azobenzene derivatives have gradually developed from traditional dyes into various types of molecules with photo-tunable material properties, including biological macromolecules, polymers, hybrid materials, inorganic materials, and metal-organic frameworks, etc. For example, Woolley et al. reported azo molecules with a "coplanar" structure and achieved the configuration transformation under green / blue light excitation.

[0003] However, currently, the isomerization of most azobenzene derivatives is still limited to the light-driven E / Z configuration change, and the isomerization types are relatively single, which limits their applications in multifunctional intelligent materials.

[0004] On the other hand, in 1977, Feringa et al. studied and found that introducing large steric hindrance groups around the double bond can disrupt the planarity of the molecule, resulting in helical chirality. Based on this, the Feringa team designed the first molecular motor capable of unidirectional 360° rotation around the double bond in 1999 and developed a series of molecular machines based on overcrowded olefins, which have been successfully applied to the motion regulation at the molecular scale, nanoscale, and even macroscale.

[0005] In addition, Fujita et al. restricted the overcrowded olefin with a trans-folded conformation in a molecular cage to induce its transformation into a twisted conformation. Okada et al. reported the (N-phenylfluorenylidene) acridine (Ph-FA) compound, characterized its folded state and twisted state by crystallography, and demonstrated stimulus-responsive behaviors such as mechanochromism, thermochromism, and vapochromism.

[0006] Currently, the research on the "overcrowded" molecular structure mainly focuses on olefins or anthraquinone compounds, and the exploration of azobenzene derivatives in this field is still blank. Summary of the Invention

[0007] To solve the problems of the existing technology, the purpose of the present invention is to provide azo derivatives with an overcrowded structure and their preparation and application methods. The azo derivatives have an overcrowded structure, which not only expands the isomerization types of azo molecules but also endows them with multiple stimulus-responsive properties, providing new ideas for the development of novel dynamic functional materials.

[0008] The technical solution of the present invention is as follows: An azobenzene derivative with an overcrowded structure, which has the following structural formula: , wherein, R is selected from an alkyl group having C1-C n or a substituted alkyl group thereof, an aromatic ring having C6-C 6n or a mono-substituted or multi-substituted product thereof, an alicyclic ring having C3-C n or a mono-substituted or multi-substituted product thereof, a heteroaromatic ring or a mono-substituted or multi-substituted product thereof, a polycyclic derivative or a mono-substituted or multi-substituted product thereof.

[0009] In the present invention, the overcrowded structure refers to a structure in which when the steric hindrance of the substituent significantly exceeds the accommodable space around the substituted object, the molecule enters an overcrowded state, and distortions such as bond angle distortion and planar configuration occur.

[0010] According to some preferred embodiments of the present invention, R is selected from any one of the following groups: Group 1: ; Group 2: ; Group 3: ; Group 4: ; Group 5: ; Group 6: ; Group 7: ; Group 8: .

[0011] According to some preferred embodiments of the present invention, R is selected from any one of the following groups: Group 9: ; Group 10: ; Group 11: ; Group 12: ; Group 13: ; Group 14: .

[0012] According to some preferred embodiments of the present invention, the azobenzene derivative has multiple configurations, including a cis-folded configuration, a trans-parallel configuration, and a trans-crossed configuration. Among them, the cis-folded configuration means that the two benzene rings connected by the cis-azo bond in the azobenzene derivative are located on the same side, forming a mutually folded molecular configuration; the trans-parallel configuration means that the dihedral angle between the two benzene rings connected by the trans-azo bond in the azobenzene derivative is close to or equal to 0°, forming a molecular configuration in which the substituents at both ends are generally parallel; the trans-crossed state means that the two benzene rings connected by the trans-azo bond in the azobenzene derivative cross each other at a certain dihedral angle, forming a configuration in which the substituents at both ends are generally in a tetrahedral state.

[0013] According to some preferred embodiments of the present invention, the azobenzene derivative can be converted between two or more configurations, and a corresponding color change occurs.

[0014] For example, the azobenzene derivative can be converted between the trans-parallel configuration and the trans-crossed configuration, and a corresponding conversion between yellow and purple occurs.

[0015] The present invention further provides a method for preparing the above-mentioned azobenzene derivative, which includes: (1) Adding the compound shown in Formula I, i.e., Compound I, a phenylboronic acid derivative, a palladium catalyst, and a base into a reaction vessel, and then adding an organic solvent and water to obtain a reaction mixture; (2) Degassing the reaction mixture, and then heating and reacting at 90 - 110 °C under an inert atmosphere. After the reaction is completed, it is cooled to room temperature, the solvent is removed and purified to obtain the azobenzene derivative; 。

[0016] The present invention designs and synthesizes an azobenzene derivative with an overcrowded structure through the Suzuki-Miyaura reaction (Suzuki reaction), and its reaction mechanism includes: First, oxidative addition of the azobenzene bromide with zero-valent palladium occurs, and it reacts with a base to form a strongly electrophilic organopalladium intermediate. At the same time, boric acid or borate ester reacts with a base to form an anionic complex tetravalent borate intermediate. Then, transmetalation occurs to obtain a Pd(II) intermediate coordinated with two hydrocarbon groups. Finally, reductive elimination occurs to obtain the target product and regenerate the Pd(0) catalyst.

[0017] According to some preferred embodiments of the present invention, the phenylboronic acid derivative is selected from one or more of 4-formylphenylboronic acid, 4-biphenylboronic acid, 4-(4-pyridyl)phenylboronic acid pinacol ester, 4'-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-[1,1'-biphenyl]-4-carbaldehyde, [1,1':4',1''-terphenyl]-4-ylboronic acid, 4-methylbiphenylboronic acid, N-Boc-4-aminophenylboronic acid pinacol ester, and 4-cyano-4-biphenylboronic acid.

[0018] According to some preferred embodiments of the present invention, the palladium catalyst is selected from tetrakis(triphenylphosphine)palladium.

[0019] According to some preferred embodiments of the present invention, the base is selected from potassium carbonate.

[0020] According to some preferred embodiments of the present invention, the organic solvent is selected from dioxane.

[0021] According to some preferred embodiments of the present invention, the molar ratio of the compound I to the phenylboronic acid derivative is 1:4-13.

[0022] According to some preferred embodiments of the present invention, the molar amount of the palladium catalyst is 1-10% of the molar amount of the compound I.

[0023] According to some preferred embodiments of the present invention, the molar amount of the base is 5-20 times the molar amount of the compound 1.

[0024] According to some preferred embodiments of the present invention, the volume ratio of the water to the organic solvent is 1:2-4.

[0025] The present invention further proposes the use of the above-mentioned azobenzene derivatives as colorants, smart color-changing agents or color developers, including as one or more of colorants, photochromics, mechanical colorants, thermochromics, gasochromics, solvent colorants and multi-responsive color developers.

[0026] The above applications are based on the following unexpected findings: When the azobenzene derivative is in a trans-cross configuration (hereinafter referred to as the cross configuration), it appears purple, and when it is in a trans-parallel configuration (hereinafter referred to as the parallel configuration), it appears yellow; when the azobenzene derivative with a purple or close-to-purple cross configuration is in a solvent or solvent atmosphere such as methanol, ethanol, ether, isopropanol, dichloromethane, chloroform, ethyl acetate, acetone, etc., it can be converted into a yellow parallel configuration; when the azobenzene derivative with a yellow parallel configuration is subjected to mechanical forces such as grinding and ball milling, it can be converted into a cross configuration close to purple; when the azobenzene derivative with a yellow parallel configuration is subjected to temperature change, it can be converted into a purple cross configuration.

[0027] The present invention has the following beneficial effects: Most of the current overcrowded structural molecules are limited to olefins or anthraquinone compounds, while the present invention provides a new azobenzene derivative with an overcrowded structure. The derivative uses azobenzene as the central unit and introduces a variety of functional group units as side chains. Through the influence of the length and group of the side chains, azo molecules with various configurations such as trans-cross state configuration and trans-parallel state configuration based on the overcrowded state are constructed. The azobenzene derivative can realize the mutual conversion between structures through solvent chromism, mechanochromism, vapor chromism, thermochromism, etc., and has the potential to realize functions similar to molecular machines, and can be used as a new type of ink or colorant and smart color-changing agent or color developer. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The NMR spectrum of DTPD with R group being group 1.

[0029] Figure 2 The (a) microscopic image and (b) structural schematic diagram of the crystal of DTPD with R group being group 1.

[0030] Figure 3 The X-ray diffraction spectrum of DTPD with R group being group 1.

[0031] Figure 4 The NMR spectrum of DPQD with R group being group 2.

[0032] Figure 5 The (a) microscopic image and (b) structural schematic diagram of the crystal of DPQD with R group being group 2.

[0033] Figure 6 The X-ray diffraction spectrum of DPQD with R group being group 2.

[0034] Figure 7 The NMR spectrum of DPTD with R group being group 3.

[0035] Figure 8 The (a) microscopic image and (b) structural schematic diagram of the crystal of DPTD with R group being group 3.

[0036] Figure 9 The X-ray diffraction spectrum of DPTD with R group being group 3.

[0037] Figure 10 The NMR spectrum of QPQD-Y with R group being group 4.

[0038] Figure 11 The NMR spectrum of QPQD-P with R group being group 4.

[0039] Figure 12 The (a) microscopic image and (b) structural schematic diagram of the crystal of QPQD-Y with R group being group 4.

[0040] Figure 13 The (a) microscopic image and (b) structural schematic diagram of the crystal of QPQD-P with R group being group 4.

[0041] Figure 14 The X-ray diffraction spectrum of QPQD-Y and QPQD-P with R group being group 4.

[0042] Figure 15 The image of the change of QPQD-P with R group being group 4 immersed in methanol.

[0043] Figure 16The image of QPQD-Y with R group being group 4 after ball milling.

[0044] Figure 17 The NMR spectrum of SPQD-Y with R group being group 5.

[0045] Figure 18 The NMR spectrum of SPQD-P with R group being group 5.

[0046] Figure 19 The schematic diagram of the crystal structure of SPQD-Y and SPQD-P with R group being group 5.

[0047] Figure 20 The image of SPQD-Y with R group being group 5 after grinding.

[0048] Figure 21 The image of SPQD-Y with R group being group 5 after heating.

[0049] Figure 22 The NMR spectrum of the azo molecule with R group being group 6.

[0050] Figure 23 The NMR spectrum of the azo molecule with R group being group 7.

[0051] Figure 24 The NMR spectrum of the azo molecule with R group being group 8. Detailed implementation manners

[0052] The present invention will be described in detail below in conjunction with examples and drawings. However, it should be understood that the examples and drawings are only used for exemplary description of the present invention and do not constitute any limitation to the protection scope of the present invention. All reasonable transformations and combinations within the scope of the inventive concept of the present invention fall within the protection scope of the present invention.

[0053] The methods or operations used in the following examples and comparative examples, unless otherwise specified, are all conventional methods or conventional operations in the art.

[0054] Example 1 Prepare an azo derivative with an overcrowded structure through the following steps: (1) Add 0.494 g of compound 1 (1 mmol), 1.2 g of 4-formylphenylboronic acid (8 mmol), 0.116 g of tetrakis(triphenylphosphine)palladium (0.1 mmol) and 2.073 g of potassium carbonate (15 mmol) into a 100 mL Schlenk flask. Then add 16 mL of dioxane and 4 mL of water to obtain a reaction mixture; (2) After degassing the reaction mixture through three freeze-pump-thaw cycles, displace it with nitrogen, stir the reaction at 100 °C for 72 h, cool the reaction mixture to room temperature after the reaction, remove the solvent by rotary evaporation, and purify it by silica gel column chromatography to obtain the product DTPD.

[0055] The yield of the product DTPD was measured to be 375 mg, and the yield rate was 62%.

[0056] Its NMR spectrum is shown in the appendix Figure 1 as follows, and the specific test results are as follows: 1 H NMR (400 MHz, (CD3)2SO, ppm): δ = 7.05 (d, 4H), 7.36 (d, 2H), 7.53 (t, 1H), 7.83 (d, 4H), 10.04 (s, 2H). Its crystal microscope and molecular structure diagram are shown in the appendix Figure 2 as shown, and the X-ray diffraction spectrum is shown in the appendix Figure 3 as shown. It can be seen that the crystal is a purple cuboid single crystal, and its single crystal structure is in a trans-crossed state. The benzene ring planes on both sides of the azo bond are crossed at a certain angle; through the comparative analysis of the experimental and simulated PXRD, the (001) plane of the lattice can be well corresponded, proving that the crystal structure has good fitting.

[0057] The test also found that the product molecule has different stimulus responses such as solvatochromism, mechanochromism, gasochromism, and thermochromism.

[0058] The R group in Example 1 was selected as:

[0059] The reaction formula is:

[0060] Example 2 Prepare an azo derivative with an overcrowded structure through the following steps: (1) Add 0.148 g of compound 1 (0.3 mmol), 0.475 g of 4-biphenylboronic acid (2.4 mmol), 0.035 g of tetrakis(triphenylphosphine)palladium (0.03 mmol), and 0.622 g of potassium carbonate (4.5 mmol) into a 50 mL Schlenk flask, and then add 4 mL of dioxane and 1 mL of water to obtain a reaction mixture; (2) After degassing the reaction mixture through three freeze-pump-thaw cycles, displace it with nitrogen, stir the reaction at 100 °C for 72 h, cool the reaction mixture to room temperature after the reaction, remove the solvent by rotary evaporation, and purify it by silica gel column chromatography to obtain the product DPQD.

[0061] The yield of the product DPQD was tested to be 105 mg, and the yield rate was 45%.

[0062] Its NMR spectrum is as attached Figure 4 as shown below, and the specific test results are as follows: 1 H NMR (400 MHz, (CD3)2SO, ppm): δ =7.05 (d, 4H), 7.32 (d, 2H), 7.38(t, 2H), 7.45 (d, 1H), 7.49 (t, 4H), 7.67 (d, 4H), 7.75 (d, 4H). Its crystal microscope and molecular structure diagram are as attached Figure 5 as shown below, and the X-ray diffraction spectrum is as attached Figure 6 as shown below. It can be seen that the crystal is a purple square flake single crystal. The single crystal structure is solved to be in a trans-crossed state by single crystal X-ray diffraction. Among them, the benzene ring planes on both sides connected by the azo bond cross each other at a certain angle; through the comparative analysis of the experimental and simulated PXRD, the (001) plane of the lattice can be well corresponded, which proves that the crystal structure has good fitting properties.

[0063] The test also found that the product molecule has different stimulus responses such as solvatochromism, mechanochromism, gasochromism, and thermochromism.

[0064] The R group in Example 2 was selected as:

[0065] The reaction formula is:

[0066] Example 3 Prepare an azo derivative with an overcrowded structure through the following steps: (1) Add 0.198 g of compound 1 (0.4 mmol), 0.9 g of 4-(4-pyridyl)phenylboronic acid pinacol ester (3.2 mmol), 0.046 g of tetrakis(triphenylphosphine)palladium (0.04 mmol), and 0.829 g of potassium carbonate (6 mmol) into a 100 mL Schlenk flask, and then add 8 mL of dioxane and 2 mL of water to obtain a reaction mixture; (2) After degassing the reaction mixture through three freeze-pump-thaw cycles, displace it with nitrogen, stir and react at 100 °C for 72 h. After the reaction, cool it to room temperature, rotary evaporate to remove the solvent, and purify it by silica gel column chromatography to obtain the product DPTD.

[0067] The yield of the product DPTD was tested to be 210 mg, and the yield rate was 66%.

[0068] Its NMR spectrum is as attached Figure 7 as shown below. The specific test results are as follows: 1H NMR (400 MHz, (CD3)2SO, ppm): δ = 7.10 (d, 4H), 7.34 (d, 2H), 7.48 (t, 1H), 7.83 (d, 8H). Its crystal microscope and molecular structure diagram are as attached Figure 8 as shown below. The X-ray diffraction spectrum is as attached Figure 9 as shown below. It can be seen that the crystal is a purple cuboid single crystal. The single crystal structure is solved by single crystal X-ray diffraction to be in a trans-crossed state. Among them, the benzene ring planes connected by the azo bond cross each other at a certain angle. Through the comparative analysis of the experimental and simulated PXRD, it is proved that the crystal structure has good fitting.

[0069] The test also found that the product molecule has different stimulus responses such as solvatochromism, mechanochromism, gasochromism, and thermochromism.

[0070] The R group in Example 3 is selected as:

[0071] The reaction formula is:

[0072] Example 4 Prepare an azo derivative with an overcrowded structure through the following steps: (1) Add 0.198 g of Compound 1 (0.4 mmol), 0.986 g of 4'-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-[1,1'-biphenyl]-4-carbaldehyde (3.2 mmol), 0.046 g of tetrakis(triphenylphosphine)palladium (0.04 mmol), and 0.829 g of potassium carbonate (6 mmol) into a 100 mL Schlenk flask. Then add 8 mL of dioxane and 2 mL of water to obtain a reaction mixture; (2) After degassing the reaction mixture through three freeze-pump-thaw cycles, displace it with nitrogen, stir and react at 100 °C for 72 h. After the reaction, cool it to room temperature and purify it by silica gel column chromatography to obtain the product QPQD.

[0073] The yield of the product QPQD was tested to be 262 mg, and the yield rate was 73%.

[0074] The dried product and the product in solution state were tested, and their NMR spectra were similar, as shown in Appendices Figure 10 and 11 respectively. Among them, the dried product QPQD-Y is a yellow parallel state structure, and the product QPQD-P in solution state is a purple cross state structure.

[0075] The specific spectral test results are as follows: 1 H NMR (400 MHz, CDCl3, ppm): δ = 7.06 (d, 4H), 7.30 (d, 2H), 7.36 (s, 1H), 7.49 (d, 4H), 7.79 (d, 4H), 8.02 (d, 4H), 10.08 (s, 2H). Among them, the crystal microscope and molecular structure diagram of QPQD-Y are shown in Appendix Figure 12 respectively. The crystal is a yellow square flake crystal. The single crystal structure is solved as a trans-parallel state by single crystal X-ray diffraction. Among them, the benzene ring planes connected by the azo bond show a parallel state. The crystal microscope and molecular structure diagram of QPQD-P are shown in Appendix Figure 13 respectively. The crystal is a purple rectangular crystal. The single crystal structure is solved as a trans-cross state by single crystal X-ray diffraction. Among them, the benzene ring planes connected by the azo bond intersect at a certain angle with each other.

[0076] The X-ray diffraction spectra of the two configurations are shown in Appendix Figure 14 respectively. Through the comparative analysis of the experimental and simulated PXRD, it is proved that the crystal structure has good fitting.

[0077] The test also found that the product molecule has different stimulus responses such as solvatochromism, mechanochromism, gasochromism, and thermochromism. For example: The solvatochromism of the obtained product was explored, and the results are shown in Appendix Figure 15 respectively. It can be seen that when the product is soaked in solvents such as methanol, ethanol, ether, and isopropanol, it can change from the purple cross state configuration to the yellow parallel state configuration, and the morphology of the crystal can maintain the rectangular shape without obvious change.

[0078] The mechanochromism of the obtained product was explored, and the results are shown in Appendix Figure 16 respectively. It can be seen that before and after ball milling, the product can change from the yellow parallel state configuration to a cross state configuration close to purple.

[0079] The R group in Example 4 was selected as:

[0080] The reaction formula is:

[0081] Example 5 An azo derivative with an overcrowded structure was prepared by the following steps: (1) 0.198 g of Compound 1 (0.4 mmol), 0.878 g of [1,1':4',1''-terphenyl]-4-ylboronic acid (3.2 mmol), 0.046 g of tetrakis(triphenylphosphine)palladium (0.04 mmol) and 0.829 g of potassium carbonate (6 mmol) were added to a 100 mL Schlenk flask, and then 8 mL of dioxane and 2 mL of water were added to obtain a reaction mixture; After the reaction mixture was degassed by three freeze-pump-thaw cycles, it was purged with nitrogen and stirred at 100 °C for 72 h. After the reaction, it was cooled to room temperature and purified by silica gel column chromatography to obtain the product SPQD.

[0082] The yield of the product SPQD was tested to be 297 mg, and the yield was 68%.

[0083] The dried product and the product in solution state were tested, and their NMR spectra were similar, as shown in the attached Figure 17 and 18 respectively. Among them, the dried product SPQD-Y was a yellow parallel state structure, and the product SPQD-P in solution state was a purple cross state structure.

[0084] The specific test results of the spectra are as follows: 1 H NMR (400 MHz, CDCl3, ppm): δ = 7.08 (d, 4H), 7.31 (d, 2H), 7.37 (t, 3H), 7.48 (s, 4H), 7.55 (d, 4H), 7.66 (d, 4H), 7.73 (d, 8H). The crystal molecular structure diagram is as shown in the attached Figure 19 The crystal of SPQD-Y was a yellow square flake crystal, and the single crystal structure was solved by single crystal X-ray diffraction to be a trans-parallel state, in which the benzene ring planes connected by the azo bond showed a parallel state. The crystal of SPQD-P was a purple rectangular crystal, and the single crystal structure was solved by single crystal X-ray diffraction to be a trans-cross state, in which the benzene ring planes connected by the azo bond intersected at a certain angle.

[0085] The test also found that the product molecule had different stimulus responses such as solvatochromism, mechanochromism, gasochromism, and thermochromism, such as: The obtained product was explored for mechanofluorochromism, and the results are as shown in the attached Figure 20As shown, it can be seen that the product with a yellow parallel configuration can be transformed into a color close to purple after being stimulated by mechanical grinding force, indicating that its configuration is transformed into a new form close to the crossed state.

[0086] The obtained product was explored for thermochromism, and the results are as attached Figure 21 As shown, it can be seen that the product with a yellow parallel configuration is successfully transformed into a purple crossed state after heating.

[0087] The R group in Example 5 is selected as:

[0088] The reaction formula is:

[0089] Example 6 An azo derivative with an overcrowded structure was prepared through the following steps: 0.198 g of Compound 1 (0.4 mmol), 0.678 g of 4-methylbiphenylboronic acid (3.2 mmol), 0.046 g of tetrakis(triphenylphosphine)palladium(0) (0.04 mmol) and 0.829 g of potassium carbonate (6 mmol) were added to a 100 mL Schlenk flask, and then 8 mL of dioxane and 2 mL of water were added to obtain a reaction mixture; (2) After the reaction mixture was degassed through three freeze-pump-thaw cycles, it was purged with nitrogen and stirred at 100 °C for 72 h. After the reaction, it was cooled to room temperature and purified by silica gel column chromatography to obtain the product.

[0090] The yield of the tested product was 162 mg and the yield was 47%.

[0091] Its NMR spectrum is as attached Figure 22 As shown, the specific test results are as follows: 1 H NMR (400 MHz, CDCl3, ppm): δ = 2.41 (s, 6H), 7.01 (d, 4H), 7.46 (d, 4H), 7.54 (d, 4H). The test also found that the product molecule has different stimulus responses such as solvatochromism, mechanochromism, gasochromism, and thermochromism.

[0092] The R group in Example 6 is selected as:

[0093] The reaction formula is:

[0094] Example 7 The azo derivative with an overcrowded structure is prepared by the following steps: (1) 0.247 g of Compound 1 (0.5 mmol), 2.075 g of N-Boc-4-aminophenylboronic acid pinacol ester (6.5 mmol), 0.058 g of tetrakis(triphenylphosphine)palladium (0.05 mmol) and 1.037 g of potassium carbonate (7.5 mmol) were added to a 100 mL Schlenk flask, and then 8 mL of dioxane and 2 mL of water were added to obtain a reaction mixture; (2) After the reaction mixture was degassed by three freeze-pump-thaw cycles, it was purged with nitrogen and stirred at 100 °C for 72 h. After the reaction, it was cooled to room temperature, the solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography.

[0095] The yield of the product was tested to be 219 mg, and the yield was 74%.

[0096] Its NMR spectrum is as attached Figure 23 and shown below. The specific test results are as follows: 1 H NMR (400 MHz, (CD3)2SO, ppm): δ = 1.46 (s, 18H), 6.80 (d, 4H), 7.21 (d, 2H), 7.38 (t, 5H), 9.37 (s, 2H). The test also found that the product molecule has different stimulus responses such as solvatochromism, mechanochromism, gasochromism, and thermochromism.

[0097] The R group in Example 7 is selected as:

[0098] The reaction formula is:

[0099] Example 8 The azo derivative with an overcrowded structure is prepared by the following steps: (1) 0.098 g of Compound 1 (0.2 mmol), 0.357 g of 4-cyano-4-biphenylboronic acid (1.6 mmol), 0.023 g of tetrakis(triphenylphosphine)palladium (0.02 mmol) and 0.415 g of potassium carbonate (3 mmol) were added to a 25 mL Schlenk flask, and then 4 mL of dioxane and 1 mL of water were added to obtain a reaction mixture; (2) After the reaction mixture was degassed by three freeze-pump-thaw cycles, it was purged with nitrogen and stirred at 100 °C for 72 h. After the reaction, it was cooled to room temperature and purified by silica gel column chromatography to obtain the product.

[0100] The yield of the tested product is 55 mg and the productivity is 31%.

[0101] Its NMR spectrum is as attached Figure 24 , and the specific test results are as follows: 1 H NMR (400 MHz, (CD3)2SO, ppm): δ = 7.10 (d, 4H), 7.33 (d, 2H), 7.47 (t, 1H), 7.79 (d, 4H), 7.96 (s, 8H). The test also found that the product molecule has different stimulus responses such as solvatochromism, mechanochromism, gasochromism, and thermochromism.

[0102] The R group in Example 8 is selected as:

[0103] The reaction formula is:

[0104] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An azobenzene derivative having an overcrowded structure, characterized in that It has the following structural formula: ， Wherein, R is selected from C1-C n Alkyl or substituted alkyl, C6-C 6n An aromatic ring or a mono- or poly-substituted product thereof, C3-C n Any one of an alicyclic ring or a mono- or poly-substituted product thereof, an aromatic heterocyclic ring or a mono- or poly-substituted product thereof, a polycyclic derivative or a mono- or poly-substituted product thereof.

2. The azobenzene derivative according to claim 1, characterized in that in, R is selected from any one of the following groups: Group 1: ; Group 2: ; Group 3: ; Group 4: ; Group 5: ; Group 6: ; Group 7: ; Group 8: .

3. The azobenzene derivative according to claim 1, characterized in that in, R is selected from any one of the following groups: Group 9: ; Group 10: ; Group 11: ; Group 12: ; Group 13: ; Group 14: .

4. The azobenzene derivative according to claim 1, characterized in that The azobenzene derivatives have a variety of configurations, including a cis-folded state configuration, a trans-parallel state configuration and a trans-crossed state configuration, wherein the cis-folded state configuration refers to the two benzene rings connected by the cis-azo bond in the azobenzene derivative are located on the same side, forming a mutually folded molecular configuration, the trans-parallel state configuration refers to the dihedral angle between the two benzene rings connected by the trans-azo bond in the azobenzene derivative is close to or equal to 0°, forming a molecular configuration in which the substituents at both ends are generally parallel, and the trans-crossed state refers to the two benzene rings connected by the trans-azo bond in the azobenzene derivative cross each other at a dihedral angle of a certain angle, forming a configuration in which the substituents at both ends are generally tetrahedral.

5. The azobenzene derivative according to claim 4, characterized in that The azobenzene derivative can be converted between two or more configurations and produce corresponding color changes.

6. The method for preparing the azobenzene derivatives according to claims 1 to 5, characterized in that: It includes: (1) adding a compound represented by formula I, i.e., compound I, a phenylboronic acid derivative, a palladium catalyst and a base into a reaction vessel, and then adding an organic solvent and water to obtain a reaction mixture; (2) degassing the reaction mixture, and then heating it at 90-110° C. under an inert atmosphere for reaction. After the reaction is completed, cooling it to room temperature, removing the solvent, and purifying it to obtain the azobenzene derivative; 。 7. The preparation method according to claim 6, characterized in that: in, The phenylboronic acid derivative is selected from one or more of 4-formylphenylboronic acid, 4-biphenylboronic acid, 4-(4-pyridyl)phenylboronic acid pinacol ester, 4'-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-[1,1'-biphenyl]-4-carboxaldehyde, [1,1':4',1''-terphenyl]-4-ylboronic acid, 4-methylbiphenylboronic acid, N-Boc-4-aminophenylboronic acid pinacol ester, and 4-cyano-4-biphenylboronic acid; and / or, the palladium catalyst is selected from tetrakis(triphenylphosphine)palladium; and / or, the base is selected from potassium carbonate; and / or, the organic solvent is selected from dioxane.

8. The preparation method according to claim 6, characterized in that: in, The molar ratio of the compound I to the phenylboronic acid derivative is 1:4-13; and / or the molar amount of the palladium catalyst is 1-10% of the molar amount of the compound I; and / or the molar amount of the base is 5-20 times the molar amount of the compound 1; and / or the volume ratio of the water to the organic solvent is 1:2-4.

9. Use of the azobenzene derivative according to claims 1-5 or the azobenzene derivative prepared by the preparation method according to any one of claims 6-8 as a colorant, smart color-changing agent or color developer, including one or more of a colorant, photochromic agent, mechanical color-changing agent, thermochromic agent, gas-chromic agent, solvent-chromic agent and multi-responsive color developer.

10. The use according to claim 9, characterized in that: The response solvent of the solvent-induced color-changing agent includes one or more of methanol, ethanol, ether, isopropanol, dichloromethane, chloroform, ethyl acetate, and acetone.

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