A method for enhancing the photooxidative coupling reaction of 4-aminothiophenol and its application

Abstract

The present invention relates to a method for enhancing the photooxidative coupling reaction of 4-aminothiophenol and its application, the method comprising: adding 4-nitrothiophenol to the photocatalytic oxidative coupling reaction system of 4-aminothiophenol, performing a catalytic reaction under the mediation of 4-nitrothiophenol, and oxidizing 4-aminothiophenol to 4,4'-dimercaptoazobenzene. The present invention proposes for the first time to enhance the photooxidative coupling reaction of 4-aminothiophenol by the mediation of 4-nitrothiophenol, which can be judged by the phenomenon that the Raman characteristic peak intensity of the photooxidative coupling product 4,4'-dimercaptoazobenzene is significantly enhanced, and it is found that the Raman characteristic peak intensity under the method is significantly greater than the linear sum of the characteristic Raman peak intensities of 4,4'-dimercaptoazobenzene detected by the catalytic reaction of two thiophenols alone. The method provides a new idea for enhancing and regulating the photooxidative coupling of 4-aminothiophenol.

Description

Technical Field

[0001] The present invention belongs to the technical field of surface enhanced Raman scattering detection, relates to a method for photooxidative coupling reaction of 4-aminothiophenol and an application thereof, and in particular to a method for enhancing the photooxidative coupling reaction of 4-aminothiophenol and an application thereof. Background Art

[0002] In recent years, the localized surface plasmon resonance (LSPR) of nanometal structures has attracted considerable attention from scientists due to its wide range of applications. LSPR-based photocatalytic reactions are a research hotspot. The principle is that LSPR generates hot carriers, namely hot electrons and holes, during its non-radiative decay process. These hot carriers are used to regulate the redox reactions of adsorbates, thus playing a catalytic role. Surface-enhanced Raman scattering (SERS), a method that uses LSPR to generate a localized strong light field to enhance vibrational spectroscopy, has become an important method for studying plasmon catalysis due to its convenience, rapidity, and high sensitivity. Reactants, reaction intermediates, and products adsorbed on the surface of nanometal structures can all be detected using SERS.

[0003] 4-Aminothiophenol and 4-nitrothiophenol are important probe molecules in SERS detection. They can be adsorbed on the surface of most nanometal structures through sulfhydryl (-SH) groups and have strong SERS characteristic peak intensity. The reduction of 4-nitrothiophenol using the LSPR of nanometal structures is a typical heterogeneous catalytic model reaction. Each 4-nitrothiophenol molecule usually undergoes four-electron reduction to generate 4,4'-dimercaptoazobenzene, which has peaks at 1143, 1390 and 1433 cm -1 The band has additional characteristic peaks, corresponding to the CN symmetric stretching, N=N stretching and CH in-plane bending modes of 4,4'-dimercaptoazobenzene; when a strong reducing agent (such as sodium borohydride) is added, a six-electron reduction process can occur to generate 4-aminobenzenethiol.

[0004] The b2 vibration mode of 4-aminothiophenol molecules on the plasmonic metal surface is compared with the molecular Raman spectrum at 1143, 1390 and 1433 cm -1Enhanced Raman peaks appeared in three bands. After debates about the mechanism of molecular isomerization, photoinduced charge transfer (CT), and charge tunneling, they were ultimately confirmed to be characteristic peaks of 4,4'-dimercaptoazobenzene, the product of the plasmon-catalyzed photooxidative coupling of 4-aminothiophenol. The photooxidative coupling reaction of 4-aminothiophenol on plasmonic metal surfaces consists of two main stages, with the role of the oxidant or electron acceptor crucial throughout the entire reaction. The first is the photoreaction stage, where oxygen in the system is activated and dissociated on the nanostructure surface under illumination. This is followed by a thermochemical reaction, where the activated oxygen reacts with 4-aminothiophenol on the surface, ultimately converting it to 4,4'-dimercaptoazobenzene through oxidative dehydrogenation. This reaction can be used to further explore the role of hot electrons in plasmon catalysis, but it has high requirements for pH, plasmonic metal, test environment, and potential. Some studies have utilized tip-enhanced Raman scattering (TERS) to improve sensitivity and spatial resolution.

[0005] Although much research has been conducted on the photooxidative coupling reaction of 4-aminothiophenol, the effect of 4-nitrothiophenol on the photooxidative coupling of 4-aminothiophenol has been largely unstudied. The present invention provides a novel method for enhancing the photooxidative coupling reaction of 4-aminothiophenol, which is of great significance for the study of its photooxidative pathway and mechanism. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the present invention aims to provide a method for photooxidative coupling reaction of 4-aminothiophenol and its application, and in particular to provide a method for enhancing photooxidative coupling reaction of 4-aminothiophenol and its application.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for enhancing the photooxidative coupling reaction of 4-aminothiophenol, comprising: adding 4-nitrothiophenol to a photocatalytic oxidative coupling reaction system of 4-aminothiophenol, and performing a catalytic reaction mediated by 4-nitrothiophenol to oxidize 4-aminothiophenol to 4,4'-dimercaptoazobenzene.

[0009] This study proposes, for the first time, the use of 4-nitrothiophenol to enhance the photooxidative coupling reaction of 4-aminothiophenol. This is demonstrated by a significant increase in the Raman peak intensity of the resulting photooxidative coupling product, 4,4'-dimercaptoazobenzene. Furthermore, the intensity of this Raman peak is significantly greater than the linear sum of the peak intensities of the 4,4'-dimercaptoazobenzene detected by the catalytic reactions of the two thiophenols alone. This method provides a new approach for enhancing and regulating the photooxidative coupling of 4-aminothiophenol.

[0010] Preferably, the photocatalyst used in the catalytic reaction includes plasmonic metal nanoparticles.

[0011] In the 4-aminothiophenol photocatalytic oxidative coupling reaction system involved in the method of the present invention, under light conditions, the photocatalyst will generate surface plasmon resonance when excited by short-wavelength, high-energy light. When the photocatalyst generates plasmon resonance, hot electrons will be generated. The hot electrons will be captured by 4-nitrothiophenol and more effectively transferred to the photooxidative coupling process of 4-aminothiophenol, thereby achieving the mediating effect of 4-nitrothiophenol on the photooxidative coupling reaction of 4-aminothiophenol.

[0012] Preferably, the plasmonic metal nanoparticles have a core-shell structure, wherein the core material is a gold nanorod and the shell material is selected from gold, silver or a gold-silver alloy, and silver or a gold-silver alloy is further preferred because when silver or a gold-silver alloy is used as the shell material of the plasmonic metal nanoparticles, the Raman characteristic peak intensity of 4,4'-dimercaptoazobenzene is more significant.

[0013] Preferably, the surface of the plasmonic metal nanoparticles is smooth or has threads, preferably has threads, because when plasmonic metal nanoparticles with threads are used as catalysts, the Raman characteristic peak intensity of 4,4'-dimercaptoazobenzene is more significant.

[0014] Smooth plasmonic metal nanoparticles are formed by directly coating gold nanorods with a metal or metal alloy, such as Au@AuAg, Au@Au, and Au@Ag. Threaded plasmonic metal nanoparticles are formed by first coating gold nanorods with L-cysteine ​​and then with a metal or metal alloy, such as Au@Cys@AuAg, Au@Cys@Au, and Au@Cys@Ag. Their preparation methods are described in a published patent (Patent Publication No. CN112300778A).

[0015] Preferably, the total concentration of 4-nitrothiophenol and 4-aminothiophenol in the catalytic reaction system is 80-120 μM, for example, 80 μM, 90 μM, 100 μM, 110 μM, 120 μM, etc. Other specific values ​​within this numerical range can be selected and will not be described in detail here.

[0016] Preferably, the molar ratio of 4-nitrothiophenol to 4-aminothiophenol is 1:9-9:1, for example, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, etc. Other specific values ​​within this numerical range can be selected and will not be detailed here. 1:3-9:1 is preferred.

[0017] The present invention also creatively discovered that when the content of 4-aminothiophenol is slightly higher than that of 4-nitrothiophenol, the coupling reaction is more enhanced, exhibiting an asymmetric volcano-type reaction.

[0018] Preferably, the concentration of the photocatalyst used in the catalytic reaction in the reaction system is 0.12-0.3nM, such as 0.12nM, 0.15nM, 0.2nM, 0.25nM, 0.3nM, etc. Other specific point values ​​within this numerical range can be selected and will not be repeated here.

[0019] Preferably, the method specifically comprises the following steps:

[0020] (1) The photocatalyst is first dispersed in an aqueous solution containing a surfactant for incubation;

[0021] (2) The mixture is then mixed with a mixed aqueous solution of 4-nitrothiophenol and 4-aminothiophenol and incubated, and a catalytic reaction is carried out under laser irradiation.

[0022] Preferably, the surfactant comprises cetyltrimethylammonium bromide (CTAB) and / or cetyltrimethylammonium chloride (CTAC).

[0023] Incubating the photocatalyst in an aqueous solution containing a surfactant is beneficial to improving the stability of the photocatalyst.

[0024] Preferably, the concentration of the surfactant in the aqueous solution is 0.25-1mM, for example, 0.25mM, 0.3mM, 0.4mM, 0.5mM, 0.6mM, 0.7mM, 0.8mM, 0.9mM, 1mM, etc. Other specific point values ​​within this numerical range can be selected and will not be described here one by one.

[0025] Preferably, the incubation temperature in step (1) is 20-50°C, for example, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, etc., preferably 30-40°C; the incubation time is 10-120 min, for example, 10 min, 20 min, 30 min, 35 min, 40 min, 45 min, 50 min, 60 min, 80 min, 120 min, etc., preferably 30-60 min. Other specific values ​​within the above numerical range can be selected and will not be repeated here.

[0026] Preferably, the incubation temperature in step (2) is 20-70°C, for example, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 60°C, 70°C, etc., preferably 30-60°C; the incubation time is 0-300min, for example, 2min, 5min, 10min, 30min, 50min, 80min, 100min, 150min, 200min, 300min, etc.

[0027] Preferably, the wavelength of the laser is 514±2 nm.

[0028] Preferably, the laser exposure time is 10-60 s, such as 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, etc., preferably 30-60 s.

[0029] Other specific point values ​​within the above numerical range can be selected and will not be described in detail here.

[0030] In a second aspect, the present invention provides application of the method according to the first aspect in studying the photooxidation pathway and mechanism of 4-aminothiophenol.

[0031] In a third aspect, the present invention provides application of the method according to the first aspect in surface enhanced Raman scattering (SERS) detection.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] This invention proposes, for the first time, the use of 4-nitrothiophenol to enhance the photooxidative coupling reaction of 4-aminothiophenol. Under illumination, the photocatalyst in the 4-aminothiophenol photocatalytic oxidative coupling reaction system undergoes surface plasmon resonance when excited by short-wavelength, high-energy light. This plasmon resonance generates hot electrons, which are captured by 4-nitrothiophenol and more efficiently transferred to the photooxidative coupling process of 4-aminothiophenol. This enhanced photooxidative coupling reaction is confirmed by a significant increase in the Raman peak intensity of the photooxidative coupling product, 4,4'-dimercaptoazobenzene. This Raman peak intensity is significantly greater than the linear sum of the 4,4'-dimercaptoazobenzene peak intensities detected when the two thiophenols are catalyzed separately. This method provides a new approach for enhancing and regulating the photooxidative coupling of 4-aminothiophenol. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a transmission electron microscopy image of Au@Cys@AuAg prepared in Example 1;

[0035] Figure 2is a transmission electron microscopy image of Au@AuAg prepared in Example 2;

[0036] Figure 3 is a transmission electron microscopy image of Au@Au prepared in Example 3;

[0037] Figure 4 is a transmission electron microscopy image of Au@Ag prepared in Example 4;

[0038] Figure 5 1 is the UV-visible-near-infrared absorption and extinction spectra of the test solutions containing different photocatalysts obtained in Example 5;

[0039] Figure 6 1 is the UV-visible-near-infrared absorption and extinction spectra of the test solutions containing the Au@Cys@AuAg catalyst and the Au@AuAg catalyst obtained in Example 5;

[0040] Figure 7 : is the Raman spectra of the test solutions containing different photocatalysts obtained in Example 5 under 514 nm laser light;

[0041] Figure 8 : is the Raman spectrum of the test solution containing Au@Cys@AuAg catalyst and Au@AuAg catalyst obtained in Example 5 under 514nm laser;

[0042] Figure 9 1 is a graph of UV-visible-near-infrared extinction spectra of the test solutions with different thiol ligand mixing ratios obtained in Example 6;

[0043] Figure 10 : is the Raman spectra of the test solutions with different thiol ligand mixing ratios obtained in Example 6 under 514 nm laser light;

[0044] Figure 11 is the Raman spectra of the test solution obtained in Example 7 under different wavelength lasers;

[0045] Figure 12 : is the Raman spectrum of the test solution obtained in Example 8 under different exposure times of 514 nm laser;

[0046] Figure 13 4-ATP, 4-NTP and 4-ATP + 4-NTP test solution obtained in Example 9 are UV-visible-near-infrared extinction spectra;

[0047] Figure 14 4-ATP, 4-NTP and 4-ATP+4-NTP test solution obtained in Example 9 are Raman spectra under 514 nm laser. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0049] The reagents and instruments used in the following examples are as follows:

[0050] Hexadecyltrimethylammonium bromide (CTAB) was purchased from Amresco; chloroauric acid (HAuCl4·3H2O) and silver nitrate (AgNO3) were purchased from Beijing Chemical Plant; ascorbic acid (AA) was purchased from Alfa Aesar; L-cysteine ​​(L-Cys) and 4-aminothiophenol (4-ATP) were purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.; and 4-nitrothiophenol (4-NTP) was purchased from Tokyo Institute of Technology (Shanghai) Chemical Industry Development Co., Ltd.

[0051] All solutions were incubated in a digital constant-temperature water bath (Jintan Kexi Instrument Co., Ltd.). UV-visible-near-infrared extinction spectra were measured using an Agilent Cary 60 spectrophotometer. Raman spectra were measured using a confocal laser Raman spectrometer (Renishaw-Invia Plus). Transmission electron microscopy images were captured using a Tecnai G2 20S-Twin microscope.

[0052] 4,4'-Dimercaptoazobenzene (DMAB) is the product of the photooxidative coupling reaction of 4-aminothiophenol (4-ATP) and the photoreduction reaction of 4-nitrothiophenol (4-NTP). The Raman spectrum characteristic peak of DMAB is 1143 cm -1 , 1390cm -1 and 1433cm -1 The amount of DMAB generated was evaluated by the intensity of these three characteristic peaks. 1143 / 1081 , I 1390 / 1081 and I 1433 / 1081 It is defined as the "DMAB ratio" and characterizes the azo coupling degree of 4-ATP.

[0053] Preparation Example 1

[0054] This preparation example provides a photocatalyst, which is a plasmonic metal nanoparticle with threads on the surface. The preparation method is as follows:

[0055] After incubating gold nanorods (AuNR) with a 15mM CTAB aqueous solution in a 30°C water bath for 30 minutes, 50μM L-Cys was added thereto, mixed evenly, and incubated in a 30°C water bath for 1 hour to obtain an incubation solution; 0.07mM AgNO3, 0.13mM HAuCl4 and 0.32mM AA aqueous solution were added to the incubation solution in sequence, mixed evenly to obtain a growth solution, which was grown in a 70°C water bath for 1 hour and centrifuged at 5000rpm for 8 minutes to obtain plasmonic metal nanoparticles with threads on the surface (hereinafter referred to as Au@Cys@AuAg).

[0056] The prepared catalyst was observed using a transmission electron microscope. Figure 1 shown.

[0057] Preparation Example 2

[0058] This preparation example provides a photocatalyst, which is a plasmonic metal nanoparticle with a smooth surface. The preparation method is as follows:

[0059] After incubating gold nanorods (AuNR) with a 15mM CTAB aqueous solution in a 30°C water bath for 30 minutes, 0.07mM AgNO3, 0.13mM HAuCl4 and 0.32mM AA aqueous solution were added to the incubation solution in sequence and mixed evenly to obtain a growth solution. The solution was placed in a 70°C water bath for 1 hour and centrifuged at 5000rpm for 8 minutes to obtain smooth-surfaced plasmonic metal nanoparticles (hereinafter referred to as Au@AuAg).

[0060] The prepared catalyst was observed using a transmission electron microscope. Figure 2 shown.

[0061] Preparation Example 3

[0062] This preparation example provides a photocatalyst, which is a plasmonic metal nanoparticle with a smooth surface. The preparation method is as follows:

[0063] After incubating gold nanorods (AuNR) with a 15mM CTAB aqueous solution in a 30°C water bath for 30 minutes, 0.2mM HAuCl4 and 3mM AA aqueous solution were added to the incubation solution in sequence, mixed evenly to obtain a growth solution, which was placed in a 70°C water bath for 1 hour and centrifuged at 5000rpm for 8 minutes to obtain smooth-surfaced plasmonic metal nanoparticles (hereinafter referred to as Au@Au).

[0064] The prepared catalyst was observed using a transmission electron microscope. Figure 3 shown.

[0065] Preparation Example 4

[0066] This preparation example provides a photocatalyst, which is a plasmonic metal nanoparticle with a smooth surface. The preparation method is as follows:

[0067] After incubating gold nanorods (AuNR) with a 15mM CTAB aqueous solution in a 30°C water bath for 30 minutes, 0.2mM AgNO3 and 3mM AA aqueous solution were added to the incubation solution in sequence, mixed evenly to obtain a growth solution, which was placed in a 70°C water bath for 1 hour and centrifuged at 5000rpm for 8 minutes to obtain smooth-surfaced plasmonic metal nanoparticles (hereinafter referred to as Au@Ag).

[0068] The prepared catalyst was observed using a transmission electron microscope. Figure 4 shown.

[0069] Example 1

[0070] This example is used to explore the effect of the catalyst prepared in Preparation Examples 1-4 on the 4-ATP photooxidative coupling reaction. The specific operation method is as follows:

[0071] 0.2nM Au@Cys@AuAg, Au@Au, Au@AuAg and Au@Ag were dispersed in a 0.5mM CTAB aqueous solution, incubated at 30°C for 30 minutes, and then injected with a 50μM 4-ATP aqueous solution. After mixing, the mixture was incubated at 30°C for 180 minutes to obtain a test solution system. After recording the extinction of each test solution system using a UV-Vis-NIR absorption spectrometer, the test solution was placed under a 514nm laser for Raman spectroscopy and a 1143cm -1 , 1390cm -1 and 1433cm -1 The intensity of the three characteristic peaks was used to evaluate the amount of DMAB generated.

[0072] The UV-visible-near infrared absorption spectrum and Raman spectrum results of the test solution system are as follows: Figure 5-6 、 Figure 7-8 The results in the figure show that gold and silver, two plasmonic metals, respond differently to the photooxidative coupling reaction described herein, with silver responding more strongly to the reaction than gold. Furthermore, photocatalysts with threaded surfaces are more effective than those with smooth surfaces.

[0073] Example 2

[0074] This example is used to investigate the effect of different concentration ratios of 4-NTP and 4-ATP in the reaction system on the 4-NTP-mediated 4-ATP photooxidative coupling reaction of the catalyst prepared in Example 1. The specific operation method is as follows:

[0075] 0.2nM Au@Cys@AuAg was dispersed in a 0.5mM CTAB aqueous solution and incubated at 30°C for 30 minutes. The solution was then divided into seven equal parts and injected with a mixed solution of thiol ligands with different 4-NTP and 4-ATP concentration ratios (the total concentration of the thiol ligands was 100μM, of which the 4-NTP concentrations were 0μM, 10μM, 25μM, 50μM, 75μM, 90μM and 100μM, respectively). After mixing evenly, the solution was incubated at 30°C for 180 minutes to obtain a test solution system. After recording the extinction of each test solution system using a UV-Vis-NIR absorption spectrometer, the test solution was placed under a 514nm laser for Raman spectroscopy and a 1143cm -1 , 1390cm -1 and 1433cm -1 The intensity of the three characteristic peaks was used to evaluate the amount of DMAB generated.

[0076] The UV-visible-near infrared absorption spectrum and Raman spectrum results of the test solution system are as follows: Figure 9 、 Figure 10 As shown in the figure, the Raman peak intensity of the reaction product of the 4-NTP and 4ATP mixture under 514nm laser light is significantly higher than that of the reaction products of 4-NTP or 4ATP alone. Furthermore, the degree of 4-ATP oxidation (expressed as DMAB signal intensity) is significantly enhanced at high 4-ATP coverage, exhibiting an asymmetric volcano pattern. This indicates that the photooxidative coupling reaction of 4-ATP can be enhanced under the mediation of 4-NTP.

[0077] Example 3

[0078] This example is used to investigate the effects of different wavelength lasers on the catalyst prepared in Example 1 on the 4-NTP-mediated 4-ATP photooxidative coupling reaction. The specific operation method is as follows:

[0079] 0.2nM Au@Cys@AuAg was dispersed in a 0.5mM CTAB aqueous solution and incubated at 30°C for 30 minutes. Then, a 50μM 4-NTP and 50μM 4-ATP sulfhydryl ligand mixed solution was injected, mixed evenly, and incubated at 30°C for 180 minutes to obtain a test solution system. The test solution was divided into three equal parts and subjected to Raman spectroscopy under 514nm, 633nm, and 785nm lasers, respectively. The Raman spectroscopy was also performed under 1143cm -1 , 1390cm -1and 1433cm -1 The intensity of the three characteristic peaks was used to evaluate the amount of DMAB generated.

[0080] The results are as follows Figure 11 The results in the figure show that the degree of 4-ATP photooxidative coupling reaction mediated by 4-NTP is stronger under 514nm laser.

[0081] Example 4

[0082] This example investigates the effects of different laser exposure times on the 4-NTP-mediated 4-ATP photooxidative coupling reaction of the catalyst prepared in Example 1. The specific operation method is as follows:

[0083] 0.2nM Au@Cys@AuAg was dispersed in a 0.5mM CTAB aqueous solution and incubated at 30°C for 30 minutes. Then, a 50μM 4-NTP and 50μM 4-ATP sulfhydryl ligand mixed solution was injected, mixed evenly, and incubated at 30°C for 180 minutes to obtain a test solution system. The test solution was divided into four equal parts and placed under a 514nm laser for Raman spectroscopy testing with laser exposure times of 10s, 20s, 30s, and 45s, respectively. The 1143cm -1 , 1390cm -1 and 1433cm -1 The intensity of the three characteristic peaks was used to evaluate the amount of DMAB generated.

[0084] The results are as follows Figure 12 As shown in the figure, the Raman characteristic peak intensity of the product of the reaction described in the present invention increases with exposure time under 514 nm laser, and the "DMAB ratio" also increases with exposure time, indicating that the 4-NTP-mediated 4-ATP oxidative coupling reaction is driven by light.

[0085] Example 5

[0086] This example investigates the relationship between the DMAB characteristic Raman peak intensities of a test solution system containing only one thiophenol and a test solution system containing two thiophenols at the same concentration. The specific operation method is as follows:

[0087] 0.2nM Au@Cys@AuAg was dispersed in a 0.5mM CTAB aqueous solution and incubated at 30°C for 30 minutes. The solution was then divided into three equal parts and injected with 50μM 4-ATP, 50μM 4-NTP, and a mixed solution of 50μM 4-ATP and 50μM 4-NTP sulfhydryl ligands, respectively. After mixing evenly, the solution was incubated at 30°C for 180 minutes to obtain a test solution system. After recording the extinction of each test solution system using a UV-Vis-NIR absorption spectrometer, the test solution was placed under a 514nm laser for Raman spectroscopy and a 1143cm -1 , 1390cm -1 and 1433cm -1 The intensity of the three characteristic peaks was used to evaluate the amount of DMAB generated.

[0088] The UV-visible-near infrared absorption spectrum and Raman spectrum results of the test solution system are as follows: Figure 13 、 Figure 14 As shown in the figure, the results show that in the method of the present invention, the degree of 4-ATP oxidative coupling mediated by 4-NTP is stronger than the linear sum of the DMAB Raman characteristic peak intensities detected by the same concentration of 4-ATP and 4-NTP, further confirming the mediating role of 4-NTP in the 4-ATP photooxidative coupling reaction.

[0089] The applicant declares that while the above-described embodiments illustrate a method for enhancing the photooxidative coupling reaction of 4-aminothiophenol and its applications, the present invention is not limited to these embodiments, nor does it necessarily rely on these embodiments for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for raw materials in the product of the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

[0090] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0091] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for enhancing the photooxidative coupling reaction of 4-aminothiophenol, characterized in that: The method comprises: adding 4-nitrothiophenol into a photocatalytic oxidative coupling reaction system of 4-aminothiophenol, and performing a catalytic reaction under the mediation of 4-nitrothiophenol to oxidize 4-aminothiophenol into 4,4'-dimercaptoazobenzene.

2. The method according to claim 1, characterized in that The photocatalyst used in the catalytic reaction includes plasmon metal nanoparticles.

3. The method according to claim 2, characterized in that The plasmonic metal nanoparticles are of a core-shell structure, wherein the core material is a gold nanorod and the shell material is selected from gold, silver or a gold-silver alloy.

4. The method according to claim 2, characterized in that The surface of the plasmon metal nanoparticles is smooth or has threads.

5. The method according to claim 4, characterized in that The surface of the plasmon metal nanoparticles is threaded.

6. The method according to claim 1, characterized in that The total concentration of the 4-nitrothiophenol and 4-aminothiophenol in the catalytic reaction system is 80-120 μM.

7. The method according to claim 1, characterized in that The molar ratio of the 4-nitrothiophenol to the 4-aminothiophenol is 1:9-9:

1.

8. The method according to claim 7, characterized in that The molar ratio of the 4-nitrothiophenol to the 4-aminothiophenol is 1:3-9:

1.

9. The method according to claim 1, characterized in that The concentration of the photocatalyst used in the catalytic reaction in the reaction system is 0.12-0.3 nM.

10. The method according to claim 1, characterized in that The method specifically comprises the following steps: (1) The photocatalyst is first dispersed in an aqueous solution containing a surfactant for incubation; (2) The mixture is then mixed with a mixed aqueous solution of 4-nitrothiophenol and 4-aminothiophenol and incubated, and a catalytic reaction is carried out under laser irradiation.

11. The method according to claim 10, characterized in that The surfactant includes cetyltrimethylammonium bromide and / or cetyltrimethylammonium chloride.

12. The method according to claim 10, characterized in that The concentration of the surfactant in the aqueous solution is 0.25-1 mM.

13. The method according to claim 10, characterized in that The incubation temperature in step (1) is 20-50° C. and the incubation time is 10-120 min.

14. The method according to claim 13, characterized in that The incubation temperature in step (1) is 30-40°C.

15. The method according to claim 13, characterized in that The incubation time in step (1) is 30-60 minutes.

16. The method according to claim 10, characterized in that The incubation temperature in step (2) is 20-70° C. and the incubation time is 0-300 min.

17. The method according to claim 16, characterized in that The incubation temperature in step (2) is 30-60°C.

18. The method according to claim 10, wherein: The wavelength of the laser is 514±2 nm.

19. The method according to claim 10, characterized in that The exposure time of the laser is 10-60s.

20. The method according to claim 19, characterized in that The exposure time of the laser is 30-60s.

21. Use of the method according to any one of claims 1 to 20 in studying the photooxidation pathway and mechanism of 4-aminothiophenol.

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