Azobenzene derivatives with overcrowded structures and their preparation and application methods

Abstract

This invention discloses an azobenzene derivative with an overcrowded structure and its preparation and application methods. It belongs to the technical field of azobenzene derivatives. The azobenzene derivative uses azobenzene as the central unit and introduces various functional groups as branches. Through the influence of branch length and functional groups, various configurations based on the overcrowded state can be formed, such as trans-crossed and trans-parallel configurations. This azobenzene derivative can achieve interconversion between structures through solvochromism, mechanochromism, gas chromism, and thermochromism, possessing the potential to achieve functions similar to molecular machines. It can be applied as a novel ink or colorant, as well as a smart color-changing agent or color developer.

Description

Technical Field

[0001] This invention belongs to the technical field of azobenzene derivatives, and particularly relates to azobenzene derivatives with overcrowded structures and their preparation and application methods. Background Technology

[0002] Azobenzene exhibits photoisomerization, transforming from a more stable E configuration to a Z configuration under light irradiation, a process known as E / Z isomerization. Since the discovery of this photoisomerization property, azobenzene derivatives have gradually evolved from traditional dyes into various types of molecules with phototunable material properties, including biomacromolecules, polymers, hybrid materials, inorganic materials, and metal-organic frameworks. For example, Woolley et al. reported a similar "coplanar" structure azo molecule and achieved its configurational transformation under green / blue light excitation.

[0003] However, the isomerization of most azobenzene derivatives is currently limited to light-driven E / Z configuration changes, resulting in a relatively limited range of isomer types and restricting their application in multifunctional smart materials.

[0004] On the other hand, in 1977, Feringa et al. discovered that introducing sterically hindered groups around double bonds could disrupt the planarity of molecules, leading to helical chirality. Based on this, Feringa's team designed the first molecular motor capable of rotating 360° unidirectionally around double bonds in 1999, and developed a series of molecular machines based on overcrowded alkenes, which were successfully applied to motion control at the molecular, nanoscale, and even macroscopic scales.

[0005] Furthermore, Fujita et al. induced the transformation of overcrowded olefins in their trans-folded conformation into a twisted conformation by confining them within molecular cages. Okada et al. reported on (N-phenylfluoreneyl)acridine (Ph-FA) compounds, characterizing their folded and twisted states using crystallography and demonstrating stimulus-response behaviors such as mechanochromism, thermochromism, and vapochromism.

[0006] Currently, research on "overcrowded" molecular structures mainly focuses on alkenes or anthraquinones, while the exploration of azobenzene derivatives in this field remains a blank. Summary of the Invention

[0007] To address the problems of existing technologies, the present invention aims to propose an azo derivative with an overcrowded structure and its preparation and application methods. This azo derivative has an overcrowded structure, which not only expands the isomer types of azo molecules but also endows them with multiple stimulus responsiveness, providing a new approach for the development of novel dynamic functional materials.

[0008] The technical solution of the present invention is as follows:

[0009] Azobenzene derivatives with overcrowded structures have the following structural formulas:

[0010] ,

[0011] Wherein, R is selected from C1-C n Alkyl groups or substituted alkyl groups thereof, C6-C 6n Aromatic rings or their mono- or poly-substituted derivatives, C3-C n Any one of the following: alicyclic compounds or their mono- or polysubstituted derivatives, aromatic heterocyclic compounds or their mono- or polysubstituted derivatives, polycyclic derivatives or their mono- or polysubstituted derivatives.

[0012] The overcrowded structure described in this invention refers to a structure in which the molecule enters an overcrowded state and exhibits distortions such as bond angle distortion and planar configuration when the steric hindrance of the substituent significantly exceeds the space available for the substituted substance.

[0013] According to some preferred embodiments of the present invention, R is selected from any of the following groups:

[0014] Group 1: Group 2: Group 3: Group 4: ;

[0015] Group 5: Group 6: Group 7: Group 8: .

[0016] According to some preferred embodiments of the present invention, R is selected from any of the following groups:

[0017] Group 9: Group 10: Group 11: Group 12: Group 13: Group 14: .

[0018] 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. The cis-folded configuration refers to the two benzene rings connected by cis-azo bonds in the azobenzene derivative being located on the same side, forming a molecular configuration that folds together. The trans-parallel configuration refers to the dihedral angle between the two benzene rings connected by trans-azo bonds in the azobenzene derivative being close to or equal to 0°, forming a molecular configuration where the substituents at both ends are generally parallel. The trans-crossed configuration refers to the two benzene rings connected by trans-azo bonds in the azobenzene derivative intersecting each other at a certain dihedral angle, forming a configuration where the substituents at both ends are generally tetrahedral.

[0019] According to some preferred embodiments of the present invention, the azobenzene derivative can switch between two or more configurations and produce corresponding color changes.

[0020] For example, the azobenzene derivative can switch between the trans parallel configuration and the trans cross configuration, resulting in a corresponding transition between yellow and purple.

[0021] This invention further provides a method for preparing the above-mentioned azobenzene derivative, comprising:

[0022] (1) The compound shown in Formula I, namely compound I, phenylboronic acid derivative, palladium catalyst and base are added to a reaction vessel, followed by the addition of organic solvent and water to obtain a reaction mixture;

[0023] (2) The reaction mixture is degassed and then heated at 90-110°C under an inert atmosphere. After the reaction is completed, it is cooled to room temperature, the solvent is removed and the mixture is purified to obtain the azobenzene derivative.

[0024] .

[0025] This invention designs and synthesizes an azobenzene derivative with an overcrowded structure via the Suzuki-Miyaura reaction (Suzuki reaction). The reaction mechanism includes: firstly, the azobenzene bromide undergoes oxidative addition with zero-valent palladium, which reacts with a base to generate a strongly electrophilic organic palladium intermediate. Simultaneously, boric acid or borate ester reacts with a base to generate a tetravalent borate intermediate, which is an anion-type complex. Then, transmetallation occurs to obtain a dihydrocarbon-coordinated Pd(II) intermediate. Finally, the target product is obtained through reductive elimination, and the Pd(0) catalyst is regenerated.

[0026] 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-dioxoboronyl-2-yl)-[1,1'-biphenyl]-4-carboxaldehyde, [1,1':4',1''-triphenyl]-4-ylboronic acid, 4-methylbiphenylboronic acid, N-Boc-4-aminophenylboronic acid pinacol ester, and 4-cyano-4-biphenylboronic acid.

[0027] According to some preferred embodiments of the present invention, the palladium catalyst is selected from tetra(triphenylphosphine)palladium.

[0028] According to some preferred embodiments of the present invention, the alkali is selected from potassium carbonate.

[0029] According to some preferred embodiments of the present invention, the organic solvent is selected from dioxane.

[0030] According to some preferred embodiments of the present invention, the molar ratio of compound I to the phenylboronic acid derivative is 1:4-13.

[0031] According to some preferred embodiments of the present invention, the molar amount of the palladium catalyst is 1-10% of the molar amount of compound I.

[0032] 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.

[0033] According to some preferred embodiments of the present invention, the volume ratio of water to organic solvent is 1:2-4.

[0034] The present invention further proposes the application of the above-mentioned azobenzene derivatives as colorants, smart color-changing agents or color-developing agents, including as one or more of colorants, photochromic agents, mechanochromic agents, thermochromic agents, gas-induced color-changing agents, solvent-induced color-changing agents and multi-response color-developing agents.

[0035] The above application is based on the following unexpected discovery:

[0036] When the azobenzene derivative is in the trans-cross configuration (hereinafter referred to as the cross configuration), it is purple; when it is in the trans-parallel configuration (hereinafter referred to as the parallel configuration), it is yellow. When the purple or nearly purple cross configuration azobenzene derivative is exposed to solvents or solvent atmospheres such as methanol, ethanol, diethyl ether, isopropanol, dichloromethane, chloroform, ethyl acetate, and acetone, it can be converted into the yellow parallel configuration. When the yellow parallel configuration azobenzene derivative is subjected to mechanical forces such as grinding or ball milling, it can be converted into the nearly purple cross configuration. When the temperature is changed, the yellow parallel configuration azobenzene derivative can be converted into the purple cross configuration.

[0037] The present invention has the following beneficial effects:

[0038] Most currently available overcrowded molecular structures are limited to alkenes or anthraquinones, while this invention provides a novel azobenzene derivative with an overcrowded structure. This derivative uses azobenzene as the central unit and introduces various functional groups as branches. By influencing the length of the branches and the groups involved, azo molecules with multiple configurations, such as trans-cross and trans-parallel configurations, are constructed based on the overcrowded state. This azobenzene derivative can achieve interconversion between structures through solvation chromaticity, mechanochromaticity, vapochromaticity, and thermochromaticity, possessing the potential to achieve functions similar to molecular machines. It can be applied as a novel ink or colorant, as well as a smart color-changing agent or developer. Attached Figure Description

[0039] Figure 1 The NMR spectrum of DTPD with R group as group 1.

[0040] Figure 2 (a) Microscopic image and (b) schematic diagram of the crystal structure of DTPD with R group as group 1.

[0041] Figure 3 The X-ray diffraction pattern of DTPD with R group as group 1.

[0042] Figure 4 The NMR spectrum of DPQD with R group as group 2.

[0043] Figure 5 (a) Microscopic image and (b) schematic diagram of the crystal structure of DPQD with R group as group 2.

[0044] Figure 6 The X-ray diffraction pattern of DPQD with R group as group 2.

[0045] Figure 7The NMR spectrum of DPTD with R group as the group 3.

[0046] Figure 8 (a) Microscopic image and (b) schematic diagram of the crystal structure of DPTD with R group as group 3.

[0047] Figure 9 The X-ray diffraction pattern of DPTD with R group as group 3.

[0048] Figure 10 The NMR spectrum of QPQD-Y with R group 4 is shown.

[0049] Figure 11 The NMR spectrum of QPQD-P with R group 4 is shown.

[0050] Figure 12 (a) Microscopic image and (b) schematic diagram of the structure of QPQD-Y crystal with R group as group 4.

[0051] Figure 13 (a) Microscopic image and (b) schematic diagram of the structure of QPQD-P with R group as group 4.

[0052] Figure 14 X-ray diffraction patterns of QPQD-Y and QPQD-P with R group 4.

[0053] Figure 15 Images showing the changes in QPQD-P with R group 4 after immersion in methanol.

[0054] Figure 16 Images showing the changes in QPQD-Y with R group 4 after ball milling.

[0055] Figure 17 The NMR spectrum of SPQD-Y with R group 5 is shown.

[0056] Figure 18 The NMR spectrum of SPQD-P with R group 5 is shown.

[0057] Figure 19 The diagram shows the crystal structures of SPQD-Y and SPQD-P with R group 5.

[0058] Figure 20 Images showing the changes in SPQD-Y after grinding, where R is the group 5.

[0059] Figure 21 Image of SPQD-Y with R group 5 after heating.

[0060] Figure 22 The NMR spectrum of an azo molecule with R group 6 is shown.

[0061] Figure 23 The NMR spectrum of an azo molecule with R group 7 is shown.

[0062] Figure 24 The NMR spectrum of an azo molecule with R group 8 is shown. Detailed Implementation

[0063] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention.

[0064] Unless otherwise specified, the methods or operations used in the following embodiments and comparative examples are conventional methods or operations in the art.

[0065] Example 1

[0066] Azo derivatives with overcrowded structures were prepared by the following steps:

[0067] (1) 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) were added to a 100 mL Schlenk flask, followed by 16 mL of dioxane and 4 mL of water to obtain the reaction mixture;

[0068] (2) After the reaction mixture was degassed by three cycles of freezing-vacuuming-thawing, it was replaced 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 DTPD was obtained by silica gel column chromatography.

[0069] The tested product DTPD yielded 375 mg, with a yield of 62%.

[0070] Its NMR spectrum is attached. Figure 1 As shown, the specific test results are as follows:

[0071] 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).

[0072] Its crystal microscope image and molecular structure diagram are attached. Figure 2 The X-ray diffraction pattern is shown in the attached figure. Figure 3 As shown, the crystal is a purple cuboid single crystal with an inverse cross structure. The azo bonds connect the benzene rings on both sides, which cross each other at a certain angle. Through experimental and simulated PXRD comparison analysis, the (001) plane of the lattice can be matched well, which proves that the crystal structure has good fitting properties.

[0073] The tests also revealed that the product molecules exhibit different stimulus responses, including solvent-induced color change, mechanochromic color change, gas-induced color change, and thermochromic color change.

[0074] The R basis selection in Example 1 is as follows:

[0075]

[0076] The reaction formula is:

[0077]

[0078] Example 2

[0079] Azo derivatives with overcrowded structures were prepared by the following steps:

[0080] (1) 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) were added to a 50 mL Schlenk flask, followed by 4 mL of dioxane and 1 mL of water to obtain the reaction mixture;

[0081] (2) After the reaction mixture was degassed by three cycles of freezing-vacuuming-thawing, it was replaced 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 DPQD was obtained by silica gel column chromatography.

[0082] The yield of the product DPQD was tested to be 105 mg, with a yield of 45%.

[0083] Its NMR spectrum is attached. Figure 4 As shown, the specific test results are as follows:

[0084] 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).

[0085] Its crystal microscope image and molecular structure diagram are attached. Figure 5 The X-ray diffraction pattern is shown in the attached figure. Figure 6 As shown, the crystal is a purple square plate-shaped single crystal. Single crystal X-ray diffraction revealed that the single crystal structure is an inverse cross-state, in which the azo bond connects the benzene rings on both sides and crosses each other at a certain angle. Through experimental and simulated PXRD comparison analysis, the (001) plane of the lattice can be well matched, proving that the crystal structure has good fitting properties.

[0086] The tests also revealed that the product molecules exhibit different stimulus responses, including solvent-induced color change, mechanochromic color change, gas-induced color change, and thermochromic color change.

[0087] The R-basis selection in Example 2 is as follows:

[0088]

[0089] The reaction formula is:

[0090]

[0091] Example 3

[0092] Azo derivatives with overcrowded structures were prepared by the following steps:

[0093] (1) 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 tetra(triphenylphosphine)palladium (0.04 mmol) and 0.829 g of potassium carbonate (6 mmol) were added to a 100 mL Schlenk flask, followed by 8 mL of dioxane and 2 mL of water to obtain the reaction mixture;

[0094] (2) After the reaction mixture was degassed by three cycles of freezing-vacuuming-thawing, it was replaced 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 DPTD was obtained by silica gel column chromatography.

[0095] The yield of the product DPTD was 210 mg, with a yield of 66%.

[0096] Its NMR spectrum is attached. Figure 7 As shown, the specific test results are as follows:

[0097] 1H NMR (400 MHz, (CD3)2SO, ppm): δ =7.10 (d, 4H), 7.34 (d, 2H), 7.48(t, 1H), 7.83 (d, 8H).

[0098] Its crystal microscope image and molecular structure diagram are attached. Figure 8 The X-ray diffraction pattern is shown in the attached figure. Figure 9 As shown, the crystal is a purple cuboid single crystal. Single-crystal X-ray diffraction revealed that the single crystal structure is an inverse cross-structure, in which the azo bonds connecting the two benzene rings intersect each other at a certain angle. Comparative analysis of experimental and simulated PXRD results demonstrates that this crystal structure exhibits good fit.

[0099] The tests also revealed that the product molecules exhibit different stimulus responses, including solvent-induced color change, mechanochromic color change, gas-induced color change, and thermochromic color change.

[0100] The R-basis selection in Example 3 is as follows:

[0101]

[0102] The reaction formula is:

[0103]

[0104] Example 4

[0105] Azo derivatives with overcrowded structures were prepared by the following steps:

[0106] (1) 0.198 g of compound 1 (0.4 mmol), 0.986 g of 4'-(4,4,5,5-tetramethyl-1,3,2-dioxoboronyl-2-yl)-[1,1'-biphenyl]-4-carboxaldehyde (3.2 mmol), 0.046 g of tetra(triphenylphosphine)palladium (0.04 mmol) and 0.829 g of potassium carbonate (6 mmol) were added to a 100 mL Schlenk flask, followed by the addition of 8 mL of dioxane and 2 mL of water to obtain the reaction mixture;

[0107] (2) After the reaction mixture was degassed by three cycles of freezing-vacuuming-thawing, it was replaced 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 QPQD.

[0108] The tested product QPQD yielded 262 mg, with a yield of 73%.

[0109] The dried product and the product in solution were tested, and their NMR spectra were similar, as shown in the attached figures. Figure 10 and 11 As shown, the dried product QPQD-Y has a yellow parallel structure, while the product QPQD-P in solution has a purple cross structure.

[0110] The specific spectral test results are as follows:

[0111] 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).

[0112] The crystal microscope image and molecular structure diagram of QPQD-Y are attached. Figure 12 As shown, the crystal is a yellow, square, plate-like crystal. Single-crystal X-ray diffraction revealed that the single-crystal structure is an anti-parallel state, where the azo bonds connecting the two benzene rings exhibit a parallel arrangement. The crystal microscope and molecular structure diagram of QPQD-P are attached. Figure 13 As shown, the crystal is a purple rectangular crystal. Single-crystal X-ray diffraction revealed that the single-crystal structure is an inverse cross-structure, in which the azo bonds connect the two benzene rings that cross each other at a certain angle.

[0113] The X-ray diffraction patterns of the two configurations are attached. Figure 14 As shown, experimental and simulated PXRD comparison analysis proves that the crystal structure has good fitting properties.

[0114] The tests also revealed that the product molecules exhibit different stimulus responses, including solvochromic, mechanochromic, gas-induced, and thermochromic reactions, such as:

[0115] The obtained product was subjected to solvent-induced color change investigation, and the results are attached. Figure 15 As shown, the product can be transformed from a purple cross-shaped configuration to a yellow parallel configuration when soaked in solvents such as methanol, ethanol, diethyl ether, and isopropanol, and the morphology of the crystal can maintain a rectangular shape without significant change.

[0116] The obtained product was subjected to mechanical stress analysis, and the results are attached. Figure 16 As shown, it can be seen that before and after ball milling, the product can change from a yellow parallel configuration to a nearly purple cross configuration.

[0117] The R-basis selection in Example 4 is as follows:

[0118]

[0119] The reaction formula is:

[0120]

[0121] Example 5

[0122] Azo derivatives with overcrowded structures were prepared by the following steps:

[0123] (1) 0.198 g of compound 1 (0.4 mmol), 0.878 g of [1,1':4',1''-triphenyl]-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, followed by 8 mL of dioxane and 2 mL of water to obtain the reaction mixture;

[0124] (2) After the reaction mixture was degassed by three cycles of freezing-vacuuming-thawing, it was replaced 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.

[0125] The tested product SPQD yielded 297 mg, with a yield of 68%.

[0126] The dried product and the product in solution were tested, and their NMR spectra were similar, as shown in the attached figures. Figure 17 and 18 As shown, the dried product SPQD-Y has a yellow parallel structure, while the product SPQD-P in solution has a purple cross structure.

[0127] The specific test results of the spectrum are as follows:

[0128] 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).

[0129] Its crystal molecular structure diagram is attached. Figure 19 As shown, SPQD-Y crystals are yellow, square-shaped, plate-like crystals. Single-crystal X-ray diffraction revealed that its single-crystal structure is an anti-parallel state, where the azo bonds connecting the two benzene ring faces are parallel. SPQD-P crystals are purple, rectangular-shaped crystals. Single-crystal X-ray diffraction revealed that its single-crystal structure is an anti-crossed state, where the azo bonds connecting the two benzene ring faces intersect each other at a certain angle.

[0130] The tests also revealed that the product molecules exhibit different stimulus responses, including solvochromic, mechanochromic, gas-induced, and thermochromic reactions, such as:

[0131] The obtained product underwent mechanochromic exploration, and the results are attached. Figure 20As shown, it can be seen that the product with the yellow parallel configuration can be transformed into a color close to purple after being stimulated by grinding mechanical force, indicating that its configuration has transformed into a new form close to the cross-state.

[0132] The thermochromic effects of the obtained product were investigated, and the results are attached. Figure 21 As shown, the product with the yellow parallel configuration successfully transformed into the purple cross configuration after heating.

[0133] The R-basis selection in Example 5 is as follows:

[0134]

[0135] The reaction formula is:

[0136]

[0137] Example 6

[0138] Azo derivatives with overcrowded structures were prepared by the following steps:

[0139] 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 (0.04 mmol) and 0.829 g of potassium carbonate (6 mmol) were added to a 100 mL Schlenk flask, followed by the addition of 8 mL of dioxane and 2 mL of water to obtain the reaction mixture.

[0140] (2) After the reaction mixture was degassed by three cycles of freezing-vacuuming-thawing, it was replaced 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.

[0141] The tested product yield was 162 mg, with a yield of 47%.

[0142] Its NMR spectrum is attached. Figure 22 As shown, the specific test results are as follows:

[0143] 1 H NMR (400 MHz, CDCl3, ppm): δ =2.41 (s, 6H), 7.01 (d, 4H), 7.46 (d,4H), 7.54 (d, 4H).

[0144] The tests also revealed that the product molecules exhibit different stimulus responses, including solvent-induced color change, mechanochromic color change, gas-induced color change, and thermochromic color change.

[0145] The R-basis selection in Example 6 is as follows:

[0146]

[0147] The reaction formula is:

[0148]

[0149] Example 7

[0150] Azo derivatives with overcrowded structures were prepared by the following steps:

[0151] (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, followed by 8 mL of dioxane and 2 mL of water to obtain the reaction mixture;

[0152] (2) After the reaction mixture was degassed by three cycles of freezing-vacuuming-thawing, it was replaced 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.

[0153] The tested product yield was 219 mg, with a yield of 74%.

[0154] Its NMR spectrum is attached. Figure 23 As shown, the specific test results are as follows:

[0155] 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).

[0156] The tests also revealed that the product molecules exhibit different stimulus responses, including solvent-induced color change, mechanochromic color change, gas-induced color change, and thermochromic color change.

[0157] The R-basis selection in Example 7 is as follows:

[0158]

[0159] The reaction formula is:

[0160]

[0161] Example 8

[0162] Azo derivatives with overcrowded structures were prepared by the following steps:

[0163] (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, followed by 4 mL of dioxane and 1 mL of water to obtain the reaction mixture;

[0164] (2) After the reaction mixture was degassed by three cycles of freezing-vacuuming-thawing, it was replaced 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.

[0165] The tested product yield was 55 mg, with a yield of 31%.

[0166] Its NMR spectrum is attached. Figure 24 The specific test results are as follows:

[0167] 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).

[0168] The tests also revealed that the product molecules exhibit different stimulus responses, including solvent-induced color change, mechanochromic color change, gas-induced color change, and thermochromic color change.

[0169] The R-basis selection in Example 8 is as follows:

[0170]

[0171] The reaction formula is:

[0172]

[0173] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An azobenzene derivative having an overcrowded structure, characterized in that, It has the following structural formula: Wherein, R is selected from any of the following groups: Group 1: Group 2: Group 3: Group 4: Group 5: Group 6: Group 7: -NHBoc; Group 8:

2. The azobenzene derivative according to claim 1, characterized in that, The azobenzene derivative has multiple configurations, including a trans-parallel configuration and a trans-crossed configuration. The trans-parallel configuration refers to a molecular configuration where the dihedral angle between the two benzene rings connected by the trans-azo bond is close to or equal to 0°, resulting in a generally parallel state of the substituents at both ends. The trans-crossed configuration refers to a molecular configuration where the two benzene rings connected by the trans-azo bond intersect each other at a certain dihedral angle, resulting in a generally tetrahedral state of the substituents at both ends. The azobenzene derivative can switch between the trans-parallel and trans-crossed configurations, resulting in corresponding color changes.

3. The method for preparing the azobenzene derivative according to claim 1 or 2, characterized in that, It includes: (1) The compound shown in Formula I, namely compound I, phenylboronic acid derivative, palladium catalyst and base are added to a reaction vessel, followed by the addition of organic solvent and water to obtain a reaction mixture; (2) The reaction mixture was degassed and then heated at 90-110°C under an inert atmosphere. After the reaction was completed, it was cooled to room temperature, the solvent was removed and the mixture was purified to obtain the azobenzene derivative. The phenylboronic acid derivative is selected from one or more of the following: 4-formylphenylboronic acid, 4-biphenylboronic acid, 4-(4-pyridyl)phenylboronic acid pinacol ester, 4'-(4,4,5,5-tetramethyl-1,3,2-dioxoboronyl-2-yl)-[1,1'-biphenyl]-4-carboxaldehyde, [1,1':4',1”-triphenyl]-4-ylboronic acid, 4-methylbiphenylboronic acid, N-Boc-4-aminophenylboronic acid pinacol ester, and 4-cyano-4-biphenylboronic acid.

4. The preparation method according to claim 3, characterized in that, in, The palladium catalyst is selected from tetra(triphenylphosphine)palladium; and / or the base is selected from potassium carbonate; and / or the organic solvent is selected from dioxane.

5. The preparation method according to claim 3, characterized in that, in, The molar ratio of 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 compound I; and / or, the molar amount of the base is 5-20 times the molar amount of compound I; and / or, the volume ratio of water to the organic solvent is 1:2-4.

6. The application of the azobenzene derivative according to claim 1 or 2, or the azobenzene derivative prepared by the method according to any one of claims 3-5, characterized in that, The azobenzene derivative is one or more of the following: thermochromic agent, photochromic agent, mechanochromic agent, and solvochromic agent.

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