Novel photo-responsive eutectic solvent

Abstract

The invention belongs to the technical field of eutectic solvents, and discloses a novel photo-responsive eutectic solvent which is composed of an azobenzene compound and a quaternary ammonium salt compound, and the molar ratio of the azobenzene compound to the quaternary ammonium salt compound is 1: (0.5-20). The novel photoresponsive deep eutectic solvent provided by the invention takes an azobenzene compound as a hydrogen bond donor and a quaternary ammonium salt compound as a hydrogen bond receptor, and other substances do not need to be additionally introduced to drive responsive DES.

Description

Technical Field

[0001] The present invention relates to the technical field of deep eutectic solvents, and in particular to a novel type of light-responsive deep eutectic solvents. Background Art

[0002] Deep eutectic solvents (DES) are usually composed of hydrogen bond acceptors and hydrogen bond donors in a certain stoichiometric ratio. As a compound similar to ionic liquids, deep eutectic solvents have some advantages of ionic liquids, such as lower vapor pressure, good chemical stability and thermal stability, strong solubility and strong modifiability. However, compared with ionic liquids, deep eutectic solvents are mainly formed by hydrogen bonds between hydrogen bond donors and hydrogen bond acceptors to form a homogeneous system. They have a simple preparation process, high atomic utilization, low raw material price, non-toxic and harmless, and biodegradable, which is conducive to large-scale production. Responsive deep eutectic solvents are deep eutectic solvents with specific functional groups. These functional groups can undergo reversible changes under external stimuli (such as temperature, pH value changes, etc.), thereby changing their physicochemical properties. This responsiveness makes different stimulus-responsive deep eutectic solvents have potential application value in the fields of smart materials, drug delivery systems, etc. For example, by adjusting the functional groups in the responsive deep eutectic solvent, the drug release process can be controlled, thereby improving the bioavailability and therapeutic effect of the drug. The emergence of responsive low eutectic solvents has expanded and optimized the application of DES in sample preparation. With its efficient extraction and separation effect, green extraction principle and multifunctional advantages, it has become one of the most promising and valuable research topics in the sample pretreatment process.

[0003] At present, the research on responsive low eutectic solvents mainly focuses on three aspects: (1) CO2 / N2 adsorption. CO2 / N2 has become a recognized trigger for switchable solvents. CO2 / N2 can significantly change the properties of certain switchable materials, including solvents, surfactants, catalysts, polymers, gels, etc. The most attractive advantage of CO2 / N2-driven DESs is that DESs can be recycled. (2) pH responsiveness. By adding appropriate proton donors and deprotonating agents to the solution system containing the analyte and adjusting the pH value of the system, the switching of DES is completed. Without additional equipment, the extraction and separation of the target analyte can be continuously completed in the solution system. (3) Temperature responsiveness. In the hydrophobic DESs system, water is added to form a mixed two-phase system, and the system temperature is changed to drive the formation of a homogeneous system, which is called temperature-responsive DES.

[0004] However, although changing the pH value of the system, adding water or alternately bubbling CO2 / N2 can have a specific response effect on the properties of the responsive low eutectic solvent, these response pathways require the introduction of additional substances to complete the phase switching, which may have a negative impact on the analysis of certain specific targets. Summary of the invention

[0005] The present invention aims to provide a new type of photoresponsive low eutectic solvent, using azobenzene compounds as hydrogen bond donors and quaternary ammonium salt compounds as hydrogen bond acceptors, without the need to introduce additional substances to drive DES, thereby solving the problems in the background technology.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A novel photoresponsive low eutectic solvent is composed of an azobenzene compound and a quaternary ammonium salt compound, wherein the molar ratio of the azobenzene compound to the quaternary ammonium salt compound is 1:0.5-20.

[0008] Furthermore, the azobenzene compound is one or more of H, hydroxyl, carboxyl, sulfonic acid and amino groups on both benzene rings; the quaternary ammonium salt compound is one or more of monoquaternary ammonium salt, diquaternary ammonium salt and triquaternary ammonium salt.

[0009] The beneficial effects of the technical solution are:

[0010] 1. The present invention uses azobenzene compounds as hydrogen bond donors to form a new type of light-responsive low eutectic solvent with quaternary ammonium salt compounds. Compared with the three traditional responsive low eutectic solvents, no additional substances need to be introduced to drive DES, which solves the negative impact of temperature responsiveness, CO2 / N2 adsorption and pH responsive low eutectic solvents on the solvent due to the need to introduce additional substances;

[0011] 2. The raw materials of the present invention are widely available, low in cost, and simple in preparation method. No inorganic acid or alkali is required, and the product can be recycled and reused repeatedly. It will not cause the generation of a large amount of three wastes in the post-treatment process. Therefore, it can greatly reduce costs and reduce environmental pollution, which is conducive to the development of green chemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of the hydrogen bond network of the azobenzene compounds and the quaternary ammonium salt compounds included in the present invention;

[0013] Figure 2 is the structural formula of 4,4'-dihydroxyazobenzene (HBD) in the present invention;

[0014] Figure 3 is the structural formula of tetrabutylammonium chloride (TBAC) in the present invention;

[0015] Figure 4 The 4,4'-dihydroxyazobenzene of the present invention 1 HNMR spectrum;

[0016] Figure 5 The tetrabutylammonium chloride of the present invention 1 HNMR spectrum;

[0017] Figure 6 The present invention is a mixture of [4,4'-dihydroxyazobenzene][tetrabutylammonium chloride] (TBAC-DES) low eutectic solvent and 4,4'-dihydroxyazobenzene (HBD) 1 HNMR comparison spectra;

[0018] Figure 7 The [4,4'-dihydroxyazobenzene][tetrabutylammonium chloride] deep eutectic solvent (TBAC-DES) of the present invention is irradiated under UV for 6 hours before and after 1 HNMR comparison spectra;

[0019] Figure 8 The light response ultraviolet-visible spectrum change diagram of 4,4'-dihydroxyazobenzene (HBD) of the present invention;

[0020] In the figure, (A) is the photoresponse result of HBD at 365nm, and (B) is the photoresponse result of HBD at 440nm;

[0021] Fig. 9 This is a graph showing the change in the light response UV-visible spectrum of the [4,4'-dihydroxyazobenzene][tetrabutylammonium chloride] deep eutectic solvent (TBAC-DES) of the present invention;

[0022] In the figure, (C) is the light response result of TBAC-DES at 365nm, and (D) is the light response result of TBAC-DES at 440nm. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

[0024] A new type of photoresponsive deep eutectic solvent, composed of 4,4'-dihydroxyazobenzene and tetrabutylammonium chloride, wherein the optimal molar ratio of 4,4'-dihydroxyazobenzene and tetrabutylammonium chloride DES is 1:2; the schematic diagram of the hydrogen bond network of azobenzene compounds and quaternary ammonium salt compounds is shown in Figure 1 As shown, the structural formula of 4,4'-dihydroxyazobenzene is as follows Figure 2 As shown, the structural formula of tetrabutylammonium chloride is as follows Figure 3 As shown;

[0025] The preparation method comprises the following steps:

[0026] S1. Weigh 4,4'-dihydroxyazobenzene and tetrabutylammonium chloride according to a molar ratio of 1:1, grind and mix them in a round-bottom flask, gradually heat under stirring, and after obtaining a mixture liquid, cool and observe the changes in the properties of the mixture. If a stable DES cannot be formed, continue to add tetrabutylammonium chloride to the round-bottom flask according to the molar ratio, and heat under repeated stirring until a stable DES is formed. It was found that at a molar ratio of 1:1, HBD and HBA become unstable yellow liquids. Gradually increase the amount of quaternary ammonium salt until the molar ratio is 1:2, and the orange-red viscous liquid obtained can remain stable, and stable 4,4'-dihydroxyazobenzene and tetrabutylammonium chloride DES can be obtained;

[0027] S2. The DES obtained in S1 was placed in a vacuum drying oven for drying, the vacuum degree was controlled at 0.09 MPa, the temperature was 80° C., and the drying was performed for 6 h to obtain a novel light-responsive low eutectic solvent, namely, [4,4'-dihydroxyazobenzene][tetrabutylammonium chloride] low eutectic solvent.

[0028] The 4,4'-dihydroxyazobenzene, tetrabutylammonium chloride and the stable low eutectic solvent formed by them in Example 1 were dissolved in deuterated dimethyl sulfoxide and nuclear magnetic resonance hydrogen spectrum was performed ( 1 HNMR) detection, the results are as follows Figure 4-7 As shown. From the above H NMR spectrum ( 1 The results of HNMR (HNMR) test show that after the azobenzene compounds and quaternary ammonium salt compounds form a stable DES, the chemical position of "-OH" of 4,4'-dihydroxyazobenzene increases from 10.132ppm to 10.451ppm, and the chemical shift of "-H" adjacent to "-OH" on the benzene ring of 4,4'-dihydroxyazobenzene changes from 6.908ppm to 6.971ppm. This proves that the azobenzene compounds and quaternary ammonium salt compounds form a hydrogen bond network, and the "-OH" chemical shift decreases from 10.451ppm to 10.443ppm after UV irradiation, proving that the hydrogen bond effect of DES is affected after irradiation.

[0029] The [4,4'-dihydroxyazobenzene][tetrabutylammonium chloride] deep eutectic solvent of Example 1 and 4,4'-dihydroxyazobenzene were dissolved in tetrahydrofuran, respectively, and the change in the photoisomerization rate of azobenzene before and after forming DES was investigated. The results are as follows: Figure 8-9 As shown in the figure, the photoisomerization rate of azobenzene before and after forming DES was compared, and it was found that the photoisomerization rate of azobenzene HBD at 365nm increased from 6.26×10 -2 s is reduced to 5.15×10 -2 s, and the photoisomerization rate at 440 nm was 6.64×10 -2 s increases to 1.52×10 -1s proved that the hydrogen bond conjugation effect produced by the hydrogen bond formed after it formed DES with HBA led to a decrease in the photoisomerization rate of azobenzene HBD, and the TBAC-DES photoisomerization process could be cycled many times.

[0030] In summary, the present invention uses azobenzene compounds as hydrogen bond donors to form a new type of light-responsive low eutectic solvent with quaternary ammonium salt compounds. Compared with the traditional three types of switchable low eutectic solvents, no additional additives need to be introduced to drive DES, which solves the negative impact of temperature responsiveness, CO2 / N2 adsorption and pH responsiveness on the solvent due to the need to introduce additional substances. In addition, the raw material source of the present invention is wide, the cost is low, the preparation method is simple, the use of inorganic acids and alkalis is not required, and it can be recycled and reused repeatedly, and will not cause the generation of a large amount of three wastes in the post-treatment process. Therefore, it can greatly reduce costs and reduce pollution to the environment, which is conducive to the development of green chemistry.

[0031] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the technical solution of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A new type of photoresponsive deep eutectic solvent, characterized in that: The invention is composed of an azobenzene compound and a quaternary ammonium salt compound, wherein the molar ratio of the azobenzene compound to the quaternary ammonium salt compound is 1:0.5-20.

2. The novel photoresponsive deep eutectic solvent according to claim 1, characterized in that: The azobenzene compound is one or more of H, hydroxyl, carboxyl, sulfonic acid and amino groups on both benzene rings; the quaternary ammonium salt compound is one or more of monoquaternary ammonium salt, diquaternary ammonium salt and triquaternary ammonium salt.

Images