Use of a cationic cyclodextrin material in the recognition and light-controllable coating-release of azo compounds

Abstract

The application provides application of a cationic cyclodextrin material in identification and light-controllable coating-releasing of azo compounds. The cationic cyclodextrin material is combined with azo compounds in a water solution under white light irradiation, and can be dissociated from the azo compounds under ultraviolet light irradiation, and the cationic cyclodextrin material has a structure as shown in formula (I), wherein X represents a coordination anion, and the anion charge number is 4. The cationic cyclodextrin material has different identification abilities for azo compounds under different light irradiation conditions, coating and dissociation of the cationic cyclodextrin material and the azo compounds can be realized by changing the light irradiation conditions, and the cationic cyclodextrin material has a good application prospect in the field of wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of adsorption materials technology, and in particular to the application of a cationic cyclophosphine material in the recognition and light-controlled coating-release of azo compounds. Background Technology

[0002] Azo compounds are the most diverse and widely used class of synthetic dyes, applied to coloring materials in various aspects of daily life. However, the use of azo dyes and their synthesis processes, as well as wastewater discharge, have a widespread bioaccumulation and food chain transmission potential, posing a potential carcinogenic risk to humans. While some azo compounds are not carcinogenic, their toxicity is similar to that of nitro compounds and aromatic amines. Therefore, the treatment of azo dyes is increasingly attracting our attention, and finding suitable identification and capture materials to mitigate their impact on humans and the environment is crucial. Traditional techniques and materials for capturing azo compounds are diverse, such as electrochemical desorption of chromophores, photocatalysis, biological treatment, precipitation, coagulation, membrane filtration, and activated carbon adsorption. In comparison, organic adsorbents, due to their controllable molecular release, high stability, absence of heavy elements, and easy availability, have become a promising and practical alternative for achieving efficient and recyclable capture of micropollutants.

[0003] In recent years, some macrocyclic molecules have been used as crosslinking agents to generate porous organic polymers and covalent organic framework materials containing macrocycles, some of which have shown considerable promise in removing micropollutants from water. Although these materials exhibit higher removal capacity due to their much larger surface area than traditional activated carbon adsorbents, their further development is limited by their difficult synthesis, low removal efficiency, high economic cost, single capture mode, and weak interaction.

[0004] Therefore, there is a need to develop a new substance that can recognize and encapsulate azo compounds. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing adsorption materials for azo pollutants, such as high difficulty in synthesis, low removal efficiency, high economic cost, single capture method (most of which are physical adsorption, mainly depending on the size of the specific surface area) and weak interaction, and to provide a new substance for recognizing and coating azo compounds.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An application of a cationic cycloazo material in the recognition and photocontrolled coating-release of azo compounds, wherein the cationic cycloazo material, under white light irradiation, binds to azo compounds in aqueous solution to form a complex, and the complex dissociates under ultraviolet light irradiation; the cationic cycloazo material has a structure as shown in formula (I):

[0008]

[0009] In formula (I), X represents a coordinating anion with a charge of 4.

[0010] Cationic cycloazo compounds are prepared from commercially available raw materials through a simple two-step reaction, possessing electron-deficient cavities. A negatively charged azo compound can bond within the electron-deficient cavity, forming a BPy-Box. 4+ It possesses a distorted quadrilateral conformation and a unique inherent cavity. (As shown in Formula I), it may provide suitable and diverse binding sites for azo compounds through host-guest interactions, π··· anion interactions, electrostatic interactions, CH···π interactions and π···π interactions, thus exhibiting high binding capacity.

[0011] The inventors of this invention have also discovered that under ultraviolet light irradiation (such as UV = 365 nm ultraviolet light), the trans-azo compound isomerizes into the cis-azo compound, forming a host-guest complex. The ADASS will separate, remaining on the outside. Under white light irradiation, the cis-azo compound will recombine into the trans-azo compound, restoring the host-guest system and achieving photocontrollable coating and release of the guest. This indicates that by changing the light conditions, the cationic cycloazo material can achieve controllable adsorption and dissociation of azo materials, showing great application potential in the treatment of dye wastewater.

[0012] Preferably, the azo compounds include, but are not limited to, at least one of p-diaminoazobenzene, methyl orange, and sodium azobenzene-4,4'-dicarboxylate.

[0013] Among them, under room temperature (25°C) and white light irradiation conditions, the binding constant of BPy-Box·4Cl of the present invention in water and p-diaminoazobenzene (AD) (in the trans configuration under white light conditions) is K. a =2.294×10 3 M -1 The binding constant between methyl orange (MO) (in the trans configuration under white light) and methyl orange (MO) is K. a =5.434×10 3 M -1 The binding constant between it and sodium azobenzene-4,4'-dicarboxylate (ADASS) (in the trans configuration under white light conditions) is as high as K. a =4.8×10 4 M -1 .

[0014] Preferably, the concentration of the azo compound in the aqueous solution is 10. -3 ~10 4 g / L.

[0015] Preferably, X is selected from 4PF6. - 4Cl - 4Br - 4I - 4CF3COO - 2SO4 2- At least one of them.

[0016] The cationic cyclophosphine material was prepared by a method comprising the following steps:

[0017] S1,3,3'-bipyridine and α,α'-dibromo-p-xylene are mixed in a solvent, heated under reflux, and then excess hexafluorophosphate is added to precipitate the product (which is also an ion exchange reaction), thus giving intermediate BB1·2PF6.

[0018] S2. The intermediates BB1·2PF6 and α,α'-dibromo-p-xylene obtained in step S1 are mixed in a solvent and subjected to a reflux reaction. After the reaction is complete, a coordinating anion salt is added for an ion exchange reaction. The precipitate obtained by separation is the cationic cyclophosphide material (BPy-Box·4X).

[0019] In this invention, the solvents used in steps S1 and S2 can be the same or different. The solvents include, but are not limited to, one or a combination of several of the following: acetonitrile, dichloromethane, N,N-dimethylformamide, N,N-dimethylacetamide, dioxane, ethanol, methanol, tetrahydrofuran, mesitylene, and chloroform.

[0020] Preferably, in steps S1 and S2, the temperature of the reflux reaction is independently selected from 0 to 150°C, and the time of the reflux reaction is independently selected from 0.1 to 1000 h.

[0021] It should be noted that in steps S1 and S2, the temperature of the ion exchange reaction is independently selected from 0 to 150 °C.

[0022] Preferably, the molar ratio of 3,3'-bipyridine to p-dibenzyl bromide in step S1 is: 3,3'-bipyridine: p-dibenzyl bromide = (1:1000) to (1000:1).

[0023] Preferably, the molar ratio of BB1·2PF6 and p-dibenzyl bromide in step S2 is BB1·2PF6: p-dibenzyl bromide = (1:100) to (100:1).

[0024] Preferably, the hexafluorophosphate includes, but is not limited to, ammonium hexafluorophosphate (NH4PF6).

[0025] In the preparation method of the present invention, the atmosphere mixed in steps S1 and S2 can be an air atmosphere or an inert gas atmosphere.

[0026] The mixing methods include, but are not limited to, stirring and ultrasonication.

[0027] This invention uses a two-step method to prepare the material, which not only improves the utilization rate of raw materials and the yield, but also makes the prepared cationic cyclophosphine material more stable, with better iodine adsorption and recycling effects.

[0028] Preferably, a catalyst may be added in step S2 as needed, including but not limited to tetrabutylammonium iodide.

[0029] Preferably, in the preparation of cationic cyclophosphine materials, the present invention may also use a template, which is added to the reaction system in step S2. The template includes, but is not limited to, aromatic compounds, such as one or a combination of several of naphthalene, anthracene, phenanthrene, and pyrene.

[0030] In this invention, the above reaction can be carried out in a closed container commonly used in the art, including but not limited to glass bottles, round-bottom flasks, or pressure-resistant bottles.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] The cationic cyclosporine material of this invention exhibits different recognition performances for azo compounds under different light conditions. By changing the light conditions, the coating and dissociation of the cationic cyclosporine material with azo compounds can be achieved, which has great application prospects in the field of wastewater treatment. Attached Figure Description

[0033] Figure 1 This is a synthetic route diagram for the cationic cyclophosphine material BPy-Box·4Cl in Example 2;

[0034] Figure 2 The 1H NMR spectrum of the cationic cyclophosphine material BPy-Box·4PF6 in Example 1 is shown below.

[0035] Figure 3 The carbon NMR spectrum of BPy-Box·4PF6, a cationic cyclophosphine material from Example 1;

[0036] Figure 4 The 1H NMR spectrum of the cationic cyclophosphine material BPy-Box·4Cl in Example 2 is shown below.

[0037] Figure 5 The carbon NMR spectrum of the cationic cyclophosphine material BPy-Box·4Cl in Example 2 is shown below.

[0038] Figure 6The graph shows the spectral absorption changes of the complex of the cationic cycloazo material BPy-Box·4Cl and azo compounds in Example 2 after UV irradiation at 365 nm.

[0039] Figure 7 The graph shows the spectral absorption changes of the complex of the cationic cycloazo material BPy-Box·4Cl and azo compounds in Example 2 after white light irradiation.

[0040] Figure 8 The molecular model interaction diagram of the complex of the cationic cyclophosphine material BPy-Box·4Cl and methyl orange in Example 2 is obtained by density functional theory (DFT).

[0041] Figure 9 The molecular model interaction diagram of the complex of the cationic cyclophosphine material BPy-Box·4Cl and sodium azobenzene-4,4'-dicarboxylate in Example 2 was obtained by DFT calculation. Detailed Implementation

[0042] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and accompanying drawings. However, the embodiments do not limit the invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in this invention are conventional reagents, methods, and equipment in this technical field. Unless otherwise specified, all reagents and materials used in this invention are commercially available.

[0043] Example 1

[0044] This embodiment provides a cationic cyclophosphine material BPy-Box·4PF6, which is prepared by a method including the following steps:

[0045] S1. Under reflux (temperature 105℃), 1055.8 mg of p-dibenzyl bromide (4 mmol) was dissolved in 100 mL of anhydrous acetonitrile and added via a syringe pump over 24 hours to a 50 mL round-bottom flask containing 1499.4 mg of 3,3-bipyridine (9.6 mmol) of anhydrous acetonitrile. The mixture was stirred for 36 hours. The reaction was cooled to room temperature (25℃), and the solid was obtained by filtration under reduced pressure. The solid was washed three times with acetonitrile. The solid was dissolved in 30 mL of water, and excess NH4PF6 was added. The solid precipitated, was filtered under reduced pressure, and the solid was washed three times with water. The solid was freeze-dried to obtain 2.50 g of white solid, which was the intermediate BB1·2PF6.

[0046] S2. 75 mL of anhydrous acetonitrile was added to a round-bottom flask containing 93.9 mg of intermediate BB1·2PF6, 35.1 mg of p-dibenzyl bromide, and 9.8 mg of tetrabutylammonium iodide (TBAI). The reaction mixture was stirred and refluxed at 105 °C for 2.5 days. Then, the mixture was cooled to room temperature (25 °C), and an excess of the coordinating anion salt tetrabutylammonium chloride (TBACl) was added for an ion exchange reaction, precipitating a large amount of solid. The solid was then collected by centrifugation, washed three times with water, and purified as follows: The solid was dissolved in 20 mL of methanol (MeOH), and 2 mL of trifluoroacetic acid (TFA) and 2 g of diatomaceous earth were added. The mixture was then subjected to rotary distillation under reduced pressure. The evaporated sample was loaded dry and passed through an automated column press using a C14 column chromatography system. 18 The product was separated by elution with a gradient of acetonitrile and water containing 0.1% TFA on a reversed-phase column and concentrated to about 30 mL.

[0047] Then, after adding an excess of the coordinating anion salt ammonium hexafluorophosphate (NH4PF6), the sample was filtered under reduced pressure, washed three times with water, and freeze-dried to obtain 104.2 mg of purified cationic cyclophosphamide material BPy-Box·4PF6, with a yield of 72%.

[0048] The product was also characterized by nuclear magnetic resonance (NMR), and the resulting product was characterized by a hydrogen NMR spectrum as follows: Figure 2 As shown, the carbon NMR spectrum is as follows: Figure 3 As shown, the successful synthesis of the cationic cyclophosphine material BPy-Box·4PF6 is demonstrated.

[0049] Example 2

[0050] This embodiment provides a cationic cyclophosphine material BPy-Box·4Cl, the synthetic route of which is as follows: Figure 1 As shown in Example 1, 104.2 mg of BPy-Box·4PF6 prepared in Example 1 was further dissolved in 30 mL of acetonitrile, and an excess (1 g in this example) of the coordinating anion salt TBACl was added. A large amount of solid precipitated, which was filtered under reduced pressure, washed three times with acetonitrile, and dried under vacuum to obtain the cationic cyclophosphine material BPy-Box·4Cl. The yield of the product was 99%, and qualitative characterization is shown in [reference needed]. Figure 4 and Figure 5 .

[0051] Application examples

[0052] Irradiating aqueous solutions of a 1:1 0.05 mM cationic cyclophosphamide BPy-Box·4Cl: azobenzene-4,4'-dicarboxylate sodium salt host-guest complex, cationic cyclophosphamide BPy-Box·4Cl, and azobenzene-4,4'-dicarboxylate sodium salt with a UV=365 nm lamp at specific time points (0-60 min) with UV=365 nm irradiation with a UV lamp at 365 nm can reveal their changes with UV=365 nm irradiation (see...). Figure 6 The samples were then irradiated with white light, and the UV-Vis absorption spectra were measured at specific time points (0-60 min). The changes in these spectra with white light exposure can then be determined (see...). Figure 7 ).

[0053] Sodium azobenzene-4,4'-dicarboxylate underwent rapid cis-reflectoisomerization under 365 nm UV and white light irradiation. This is due to the interaction between cis-azobenzene-4,4'-dicarboxylate and the cationic cyclopane BPy-Box. 4+ The shapes do not match, and it is packaged in a BPy-Box. 4+ The sodium azobenzene-4,4'-dicarboxylate within the cavity undergoes a transformation from the trans to the cis configuration, leading to the dissociation of the host-guest complex. This dissociation was confirmed by NMR and UV-Vis spectroscopy. The trans-azo compound can interact with cationic cyclopanes (BPy-Box). 4+ It exhibits high binding capacity through host-guest interactions, π··· anion interactions, electrostatic interactions, CH····π interactions, and π···π interactions (see...). Figure 8 ,9).

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. The application of a cationic cycloazo material in the recognition and photocontrolled coating-release of azo compounds, characterized in that, The cationic cycloazo material, under white light irradiation, combines with azo compounds in aqueous solution to form a complex, which dissociates under ultraviolet light irradiation; the cationic cycloazo material has the structure shown in formula (I): Formula (I) In formula (I), X represents a coordinating anion with a charge of 4; The azo compounds include at least one of p-diaminoazobenzene, methyl orange, and sodium azobenzene-4,4'-dicarboxylate.

2. The application according to claim 1, characterized in that, X is selected from 4PF6 - 4Cl - 4Br - 4I - 4CF3COO - 2SO4 2- At least one of them.

3. The application according to claim 1, characterized in that, The preparation method of the cationic cyclophosphine material includes the following steps: S1. 3,3'-bipyridine and α,α'-dibromo-p-xylene were added to a solvent and mixed. After heating and refluxing, excess hexafluorophosphate was added to precipitate the product, thus giving intermediate BB1·2PF6. S2. The intermediates BB1·2PF6 and α,α'-dibromo-p-xylene obtained in step S1 are mixed in a solvent and then subjected to a reflux reaction. After the reaction is complete, a coordinating anion salt is added to carry out an ion exchange reaction. The precipitate obtained by separation is the cationic cyclophosphide material.

4. The application according to claim 3, characterized in that, The molar ratio of 3,3'-bipyridine to p-dibenzyl bromide in step S1 is: 3,3'-bipyridine : p-dibenzyl bromide = (1:1000) ~ (1000:1); Alternatively, the molar ratio of BB1·2PF6 and p-dibenzyl bromide in step S2 is BB1·2PF6: p-dibenzyl bromide = (1:100) ~ (100:1).

5. The application according to claim 3, characterized in that, The reflux reaction temperature in steps S1 and S2 is independently 105~150℃, and the reflux reaction time is independently 0.1~1000h.

6. The application according to claim 3, characterized in that, The solvents mentioned in steps S1 and S2 independently include one or a combination of several of the following: acetonitrile, dichloromethane, N,N-dimethylformamide, N,N-dimethylacetamide, dioxane, ethanol, methanol, tetrahydrofuran, mesitylene, and chloroform. Alternatively, step S2 may also include a catalyst, which may include tetrabutylammonium iodide.

7. The application according to claim 1, characterized in that, The concentration of the azo compound in the aqueous solution is 10. -3 ~10 4 g / L.

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