A visible light-responsive thienyl azobenzene compound

Abstract

The present application provides a visible light responsive thienyl azobenzene compound, which belongs to the technical field of azo compounds. 3-aminothiophene-2-carboxylic acid methyl ester and nitrosobenzene are added to glacial acetic acid as raw materials, and the reaction is stirred at a temperature of 40-60°C until the nitrosobenzene reaction is complete. Deionized water is added to the reaction system, extracted, the organic phases are combined, the organic phases are washed, dried, and separated by column chromatography to obtain the finished product visible light responsive thienyl azobenzene compound. The above-mentioned compound is based on readily available raw materials and has mild reaction conditions. By adjusting the types of substituents on the benzene ring of the thienyl azobenzene molecule, not only the yield of bidirectional visible light isomerization can be improved, but also the yield of the product can be significantly improved. Z The half-life of the isomers is achieved at the monthly level of half-life.

Description

Technical Field

[0001] The present application relates to a visible light responsive thienyl azobenzene compound, belonging to the technical field of azo compounds. Background Art

[0002] Azobenzene (Ph-N=N-Ph) is one of the most classic photoswitch molecules. It has attracted much attention due to its simple structure, significant geometric changes during photoisomerization, and easily regulated photoswitch performance, especially its reversible and fast response. Photoisomerization reaction, azobenzene compounds have great development potential in the fields of photoresponsive materials, photopharmacology, photodynamic drive and solar energy storage.

[0003] In practical applications, key properties of photoswitch molecules, including excitation wavelength, isomer ratio, and thermal stability, are crucial to the overall performance of the system. However, traditional azobenzene compounds struggle to balance these key properties. Conventional molecules often require harmful ultraviolet light for isomerization. Although visible-light isomerization can be achieved through substituent modification, this often significantly reduces the thermal stability of the Z isomer. Recently, the paper "Visible-Light-Activated Heteroaryl Azoswitches: Toward a More Colorful Future" (J. Am. Chem. Soc. 2024, 146, 19609-19620) foresaw the rise of heterocyclic azo molecules, providing unprecedented development opportunities for this highly anticipated field. By replacing the benzene ring at one end of the azobenzene with a heterocyclic ring and combining it with substituent modification, the photoswitch properties of the azo molecules can be significantly improved and enhanced. However, the development and application of heterocyclic azobenzene molecules still face challenges, mainly including the lack of rational molecular design, the difficulty in balancing photoswitch performance, limited synthetic methods, and the difficulty of derivatization. Summary of the Invention

[0004] In view of this, the present application provides a visible light-responsive thienyl azobenzene compound, which is not only compatible with visible light isomerization and long half-life, but also endowed with easy synthesis and easy derivatization.

[0005] Specifically, this application is implemented through the following solutions:

[0006] A visible light-responsive thienyl azobenzene compound, whose structural formula is represented by:

[0007] The thienyl azobenzene compound responds to E→Z isomerism and Z→E isomerism under visible light conditions, and the half-life of the Z isomer is ≥1.2 days.

[0008] Furthermore, as a preference:

[0009] The structural formula of the visible light responsive thienyl azobenzene compound is any one of the following structures:

[0010] The Z isomer half-life is 1.2 days, the wavelengths of the E→Z isomer light are 350 and 549 nm, and the wavelength of the Z→E isomer light is 400 nm;

[0011] The Z isomer half-life is 40.3 days, the wavelengths of the E→Z isomer light are 350 and 549 nm, and the wavelength of the Z→E isomer light is 407 nm;

[0012] The Z isomer half-life is 217.2 days, the wavelengths of the E→Z isomer light are 350, 549, and 600 nm, and the wavelength of the Z→E isomer light is 407 nm;

[0013] The Z isomer half-life is 23.2 days, the wavelengths of the E→Z isomer light are 350, 549, and 600 nm, and the wavelength of the Z→E isomer light is 407 nm;

[0014] The half-life of the Z isomer is 1.4 days, the wavelength of the E→Z isomer light is 350 and 549 nm, and the wavelength of the Z→E isomer light is 407 nm.

[0015] The thienyl azobenzene compound of the above structure achieves visible light response at a specific wavelength through heterocyclic thiophene-2-carboxylic acid methyl ester, and effectively regulates the half-life of the Z isomer by flexibly adjusting the substituents on the benzene ring.

[0016] The preparation method of the above-mentioned visible light responsive thienyl azobenzene compound is as follows: 3-aminothiophene-2-carboxylic acid methyl ester and nitrosobenzene are added to glacial acetic acid as raw materials, and the mixture is stirred at 40-60°C until the nitrosobenzene is completely reacted. Deionized water is added to the reaction system, extraction is carried out, the organic phases are combined, washed, dried, and separated by column chromatography to obtain the finished visible light responsive thienyl azobenzene compound.

[0017] The structural formula of the 3-aminothiophene-2-carboxylic acid methyl ester is:

[0018] The nitrosobenzene structural formula is: R is any possible group such as H, halogen, amino, etc.

[0019] The above preparation method has readily available raw materials, mild reaction conditions and simple synthesis. By modifying the substituents on the benzene ring of nitrosobenzene, a variety of visible light-controlled heterocyclic azobenzene photoresponsive functional molecules with long half-lives can be derived.

[0020] More preferred:

[0021] The nitroso group is any one of the following structures:

[0022]

[0023] The extraction is performed using dichloromethane for 2 to 3 times.

[0024] The washing includes washing with a saturated sodium bicarbonate solution or a saturated saline solution, and the sodium bicarbonate solution is preferably a 10% sodium bicarbonate solution.

[0025] The drying refers to drying the organic phase with anhydrous sodium sulfate.

[0026] The PE:EA ratio of the column chromatography separation is 10 to 20:1.

[0027] The reaction expression of the above process is as follows:

[0028]

[0029] The aforementioned thienyl azobenzene compounds are used as visible light-responsive photoswitch molecules. Since visible light accounts for the vast majority of sunlight, visible light responsiveness is a key performance indicator for the efficient utilization of solar energy. Furthermore, the high photoisomerization yield of azo molecules helps increase the energy density of light-to-chemical energy conversion, while their long half-life effectively enables stable energy storage. Therefore, thienyl azobenzene compounds, as advantageous core photoswitch molecules, have significant potential for molecular thermal energy storage applications.

[0030] The thienyl azobenzene compound provided in the present application can realize E→Z isomerization under 549nm green light irradiation, and can realize Z→E isomerization under 400nm blue light irradiation. By adjusting the types of substituents on the benzene ring of the thienyl azobenzene molecule, we found that not only can the yield of bidirectional visible light isomerization be improved, but also the half-life of the Z isomer can be significantly improved to the monthly level. To date, such a high thermal stability of the Z isomer has not been achieved in the field of visible light-controlled heterocyclic azo molecules, and previous reports have been limited to the daily level. In general, the present invention provides a convenient path for the development and application of long half-life visible light-controlled heterocyclic azobenzene functional molecules, and the major breakthrough in half-life is of great significance to the future development of visible light-responsive optical switch molecules. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the technical solutions in the embodiments of this application will be further described in detail below in conjunction with the embodiments of this application. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit the technical solutions of this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0032] Example 1

[0033] In this example, the synthesis of thienyl azobenzene compound methyl-3-(phenyldiazo)thiophene-2-carboxylate 1 is carried out, and the reaction formula is expressed as follows:

[0034]

[0035] The specific process is as follows:

[0036] Methyl 3-aminothiophene-2-carboxylate (0.86 g, 5.5 mmol, 1.1 eq.) and nitrosobenzene (0.54 g, 5 mmol, 1 eq.) were added to 5 mL of glacial acetic acid and stirred at 40°C. TLC monitoring indicated complete reaction of the nitrosobenzene, and the reaction was terminated. An appropriate amount of deionized water was then added to the reaction system, and the system was extracted three times with dichloromethane. The organic phases were combined. The organic phases were washed with sodium bicarbonate solution and saturated brine, respectively. The resulting organic phase was then dried over anhydrous sodium sulfate. Column chromatography (PE:EA = 10:1) afforded the product as a yellow solid (0.15 g, 12%).

[0037] 1 H NMR (400MHz, CDCl3) δ7.98 (d, J = 2.4Hz, 1H), 7.96 (d, J = 1.7Hz, 1H), 7.51 (d, J = 7.5Hz, 3H), 7.47 (s, 2H), 3.98 (s, 3H); 13 C NMR(101MHz, CDCl3)δ161.8,156.6,152.9,131.7,130.3,129.9,129.2,123.3,118.7,52.5.HRMS calculated for[C 12 H 10 N2O2S+Na] + :269.0355,found:269.0356.mp58.3-59.1℃.

[0038] Example 2

[0039] This example synthesizes methyl 3-((2,6-difluorophenyl)diazo)thiophene-2-carboxylate 2, and the reaction formula is as follows:

[0040]

[0041] The specific process is as follows:

[0042] Methyl 3-aminothiophene-2-carboxylate (0.86 g, 5.5 mmol, 1.1 eq.) and 1,3-difluoro-2-nitrosobenzene (0.72 g, 5 mmol, 1 eq.) were added to 5 mL of glacial acetic acid and stirred at 40°C overnight. An appropriate amount of deionized water was then added to the reaction system, and the reaction system was extracted three times with dichloromethane. The organic phases were combined. The organic phases were washed with sodium bicarbonate solution and saturated brine, respectively. The resulting organic phase was then dried over anhydrous sodium sulfate. Column chromatography (PE:EA = 20:1) afforded the product as a red solid (0.33 g, 23%).

[0043] 1 H NMR (400MHz, CD3CN) δ7.68(d,J=4.0Hz,1H),7.55-7.47(m,1H),7.37(d,J=4.0Hz,1H),7.18(t,J=8.0Hz,2H),3.88(s,3H); 13 C NMR(101MHz,CD3CN)δ162.2,157.9(d,J=4.0Hz),157.5,155.3(d,J=5.0Hz),133.1(t,J =10.6Hz),132.9,132.0,131.8(t,J=10.1Hz),118.9,113.9(dd,J=3.0,21.2Hz),53.2; 19 F NMR(376MHz,CD3CN)δ-122.14.HRMScalculated for[C 12 H8F2N2O2S+Na] + :305.0167,found:305.0164.mp106.6-107.5℃.

[0044] Example 3

[0045] This example synthesizes methyl 3-((2,6-dichlorophenyl)diazo)thiophene-2-carboxylate 3, and the reaction formula is as follows:

[0046]

[0047] The specific process is as follows:

[0048] Methyl 3-aminothiophene-2-carboxylate (0.86 g, 5.5 mmol, 1.1 eq.) and 1,3-dichloro-2-nitrosobenzene (0.87 g, 5 mmol, 1 eq.) were added to 5 mL of glacial acetic acid and stirred at 40°C overnight. An appropriate amount of deionized water was then added to the reaction system, and the reaction system was extracted three times with dichloromethane. The organic phases were combined. The organic phases were washed with sodium bicarbonate solution and saturated brine, respectively. The resulting organic phase was then dried over anhydrous sodium sulfate. Column chromatography (PE:EA = 20:1) afforded the product as a red solid (0.25 g, 16%).

[0049] 1 H NMR (400MHz, CD3CN) δ7.72(d,J=4.0Hz,1H),7.54(d,J=8.0Hz,2H),7.41(d,J=4.0Hz,1H),7.36(t,J=8.0Hz,1H),3.87(s,3H); 13 C NMR(101MHz,CD3CN)δ162.0,156.3,134.0,132.3,130.7,130.5,127.3,119.0,53.3.HRMS calculated for[C 12 H8Cl2N2O2S+Na] + :336.9576,found:336.9573.mp94.2-94.9℃.

[0050] Example 4

[0051] In this example, methyl 3-((2,6-dibromophenyl)diazo)thiophene-2-carboxylate 4 was synthesized, and the reaction formula is as follows:

[0052]

[0053] The specific process is as follows:

[0054] Methyl 3-aminothiophene-2-carboxylate (0.86 g, 5.5 mmol, 1.1 eq.) and 1,3-dibromo-2-nitrosobenzene (1.3 g, 5 mmol, 1 eq.) were added to 5 mL of glacial acetic acid and stirred at 40°C overnight. An appropriate amount of deionized water was then added to the reaction system, and the reaction system was extracted three times with dichloromethane. The organic phases were combined. The organic phases were washed with sodium bicarbonate solution and saturated brine, respectively. The resulting organic phase was then dried over anhydrous sodium sulfate. Column chromatography (PE:EA = 20:1) afforded the product as a red solid (0.20 g, 10%).

[0055] 1H NMR (400MHz, CD3CN) δ7.75-7.71(m,3H),7.43(d,J=4.0Hz,1H),7.20(t,J=8.0Hz,1H),3.88(s,3H); 13 C NMR(101MHz,CD3CN)δ162.0,155.8,151.0,134.2,134.1,132.3,131.3,119.0,115.3,53.3.HRMS calculated for[C 12 H8Br2N2O2S+Na] + :424.8565,found:424.8562.mp101.5-101.8℃.

[0056] Example 5

[0057] This example synthesizes methyl 3-((2-cyanophenyl)diazo)thiophene-2-carboxylate 5, and the reaction formula is as follows:

[0058]

[0059] The specific process is as follows:

[0060] Methyl 3-aminothiophene-2-carboxylate (0.86 g, 5.5 mmol, 1.1 eq.) and 2-nitrosobenzonitrile (0.66 g, 5 mmol, 1 eq.) were added to 5 mL of glacial acetic acid and stirred at 40°C overnight. An appropriate amount of deionized water was then added to the reaction system, and the reaction system was extracted three times with dichloromethane. The organic phases were combined and washed with sodium bicarbonate solution and saturated brine, respectively. The resulting organic phase was then dried over anhydrous sodium sulfate. Column chromatography (PE:EA = 15:1) afforded the product as a red solid (0.44 g, 33%).

[0061] 1 H NMR (400MHz, CD3CN) δ7.94(dd,J=20.0,8.0Hz,2H),7.81(t,J=8.0Hz,1H),7.72-7.69(m,2H),7.49(d,J=4.0Hz,1H),3.93(s,3H); 13 C NMR(101MHz,CD3CN)δ161.9,156.6,154.2,135.0,134.9,133.1,132.3,119.1,117.4,53.3.HRMS calculated for[C 13 H9N3O2S+Na] +:294.0308,found:294.0304.mp153.5-154.1℃.

[0062] Table 1: Comparison of optical switch performance parameters of thienyl azobenzene compounds with different structures

[0063]

[0064]

[0065] As can be seen from Table 1:

[0066] In terms of half-life, the thienyl azobenzene compounds synthesized in this application have a long half-life. Among the thienyl azobenzene compounds with several representative structures, the shortest half-life is 1.2 days, and the longest can reach 217.2 days, reaching a half-life of 7 months, achieving a monthly breakthrough in the half-life of visible light-controlled heterocyclic azobenzene compounds. The azobenzene compounds with the structure provided in this application achieve a significant half-life improvement, and when used as photoswitch molecules, they exhibit excellent effective and stable energy storage performance.

[0067] In terms of photoisomerization yield, E→Z isomerization can be achieved under both 350nm and 549nm illumination. Some azobenzene compounds can also undergo E→Z isomerization under 620nm illumination. The photoisomerization yield at 350nm is as low as 56.1% and as high as 97.5%. The photoisomerization yield at 549nm is as low as 34.2% and as high as 83.3%. The photoisomerization yield at 620nm remains between 46.2% and 46.8%. Z→E isomerization can be achieved under both 400nm and 407nm illumination, with a photoisomerization yield exceeding 90%. The photoisomerization yield at 407nm is as high as 96.2%. When used as a photoswitch molecule, its high photoisomerization yield is beneficial for improving the energy density of light-to-chemical energy conversion.

[0068] The thienyl azobenzene compounds of the above structure have significant advantages in half-life and visible light isomerization yield. Using thienyl azobenzene compounds as advantageous mother core photoswitch molecules has significant potential in the application of molecular thermal energy storage.

[0069] The above-described embodiments merely represent several feasible implementation methods of the present invention. The description thereof is relatively specific and detailed, but it should not be understood as limiting the scope of the invention. The embodiments are not intended to limit the scope of protection in the claims of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention. Any equivalent implementation or modification that does not depart from the scope of the present invention should be included in the technology of the present invention.

Claims

1. A visible light responsive thienyl azobenzene compound, characterized in that: Its structural formula is: The half-life of the Z isomer is 217.2 days, the wavelengths of the E→Z isomer light are 350, 549, and 600 nm, and the wavelength of the Z→E isomer light is 407 nm.

2. A method for preparing the visible light responsive thienyl azobenzene compound according to claim 1, characterized in that: 3-aminothiophene-2-carboxylic acid methyl ester and nitrosobenzene are added to glacial acetic acid, and the mixture is stirred at 40-60°C until the nitrosobenzene is completely reacted. Deionized water is added to the reaction system, and extraction is performed. The organic phases are combined, washed, dried, and separated by column chromatography to obtain a finished visible light-responsive thienyl azobenzene compound. The structural formula of the 3-aminothiophene-2-carboxylic acid methyl ester is: ; The nitrosobenzene structural formula is: .

3. The method for preparing a visible light responsive thienyl azobenzene compound according to claim 2, wherein: The extraction is performed using dichloromethane for 2 to 3 times.

4. The method for preparing a visible light responsive thienyl azobenzene compound according to claim 2, wherein: The washing includes washing with saturated sodium bicarbonate solution and saturated salt water.

5. The method for preparing a visible light responsive thienyl azobenzene compound according to claim 2, wherein: The drying refers to drying the organic phase with anhydrous sodium sulfate.

6. The method for preparing a visible light responsive thienyl azobenzene compound according to claim 2, wherein: The PE:EA ratio of the column chromatography separation is 10-20:

1.

7. The visible light responsive thienyl azobenzene compound according to claim 1, characterized in that: The visible light responsive thienyl azobenzene compound is used as a light switch molecule.

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