A Zn-MOF-PDMS chiral porous liquid material and its application

Abstract

The present invention relates to the technical field of chiral stationary phases of gas chromatography columns, and in particular to a Zn-MOF-PDMS chiral porous liquid material and its application. The Zn-MOF-PDMS chiral porous liquid material of the present invention has the characteristics of both chiral porous solid materials and liquid materials, and the synthetic raw materials are easily available, the synthetic method is relatively simple, and the column preparation cost is low; the chromatographic column of the present invention is applied to gas chromatography analysis, has a strong chiral separation ability, has good resolution performance for racemic compounds including epoxy compounds, aldehydes, alcohols, esters and ketones, and has the characteristics of fast separation speed, good resolution effect, good stability, and can be repeatedly used.

Description

Technical Field

[0001] The invention relates to the technical field of chiral stationary phases of gas chromatography columns, and in particular to a Zn-MOF-PDMS chiral porous liquid material and an application thereof. Background Art

[0002] Porous solid materials such as zeolites, MOFs and POCs need to be processed or integrated before application, which may change the material structure and reduce its performance in the process. In addition, solid materials have problems such as mechanical fatigue and physical aging, which will limit their application in industrial production. Therefore, porous solid materials are designed and synthesized to prepare new materials with permanent porosity and fluidity characteristics. Using them in the field of gas storage and separation can effectively overcome the above-mentioned shortcomings, thereby promoting the application and development of porous solid materials. Porous liquids are a new type of porous material that has developed rapidly in recent years and combines the permanent porosity of porous solids with the fluidity of liquids. The concept of porous liquid was first proposed by James in an article in 2007, and it is divided into three types according to the host system: Type I porous liquid is a pure liquid with permanent rigid pores that can be used by guest molecules but cannot self-fill; Type II porous liquid is a porous framework material dissolved in a larger volume of solvent, and the solvent molecules are blocked outside the porous molecular cavities; Type III porous liquid is a porous framework material uniformly dispersed in a steric hindered solvent, and the solvent molecules cannot enter the pores of the framework material; Type II and Type III are similar to solutions and colloidal suspensions, respectively, and Type I media have no boundary separating the porous solid material from the external medium and are true single-phase fluid systems.

[0003] The essential difference between porous liquids and porous solids lies in fluidity. Its excellent properties, such as fast mass transfer, stable kinetics and easy operation, can promote its application in storage and separation by transforming porous solid materials into free-flowing liquids with permanent porosity. Metal-organic frameworks (MOFs) have the advantages of high porosity, adjustable pores and stable chemical properties. They have attracted much attention in the synthesis of porous liquids. Therefore, new porous liquid materials based on MOFs have good development and application prospects, which is of great significance for promoting their development in many application fields. Summary of the invention

[0004] The purpose of the present invention is to address the deficiencies in the prior art and provide a Zn-MOF-PDMS chiral porous liquid material and its application as a gas chromatography stationary phase. The chiral porous liquid material based on Zn-MOF-PDMS is used as a chiral stationary phase of a chromatographic column, exhibiting excellent chiral separation performance, and can separate many chiral compounds including epoxides, aldehydes, alcohols, esters and ketones.

[0005] In order to achieve the above-mentioned object of the invention, on the one hand, the present invention provides a Zn-MOF-PDMS chiral porous liquid material, whose structure is shown in the following formula:

[0006]

[0007] On the other hand, the present invention provides a method for preparing a Zn-MOF-PDMS chiral porous liquid material, comprising the following steps:

[0008] S1. Preparation of chiral Zn-MOF: D-histidine, 2-methylimidazole and Zn(NO) in a molar ratio of 1:(7-8):(1-2) were mixed. 3 ) 2 6H 2 O mixed, stirred and reacted at 25°C for 20-30h, and Zn-MOF was obtained after washing and vacuum drying;

[0009] S2. Preparation of Zn-MOF-PDMS: Dissolve Zn-MOF and PDMS in a mass ratio of 1:(8-12) in toluene, react at 95-105°C, and after the reaction, vacuum dry to obtain Zn-MOF-PDMS.

[0010] On the other hand, the present invention provides the use of Zn-MOF-PDMS chiral porous liquid material as a gas chromatography stationary phase.

[0011] Furthermore, the Zn-MOF-PDMS chiral porous liquid material is used as a gas chromatography stationary phase to separate enantiomers.

[0012] Furthermore, the enantiomers are chiral compounds from epoxides, aldehydes, alcohols, esters and ketones.

[0013] In another aspect, the present invention provides a chromatographic column comprising the above-mentioned Zn-MOF-PDMS chiral porous liquid material as a stationary phase.

[0014] In a fifth aspect, the present invention provides a method for preparing the above-mentioned chromatographic column, comprising the following steps:

[0015] S1. Dissolve Zn-MOF-PDMS in methanol to prepare a 1-5 mg / mL stationary solution;

[0016] S2. Etching the inner wall of the capillary column with an aqueous solution of alkali, washing the inner wall with water and then washing the inner wall with an aqueous solution of acid to neutralize the residual alkali, and then washing the inner wall of the capillary column with water until the pH value of the effluent is 7, so that the inner wall of the capillary column is roughened;

[0017] S3. Fill the stationary liquid into the roughened capillary column and prepare it by static coating method.

[0018] It has been found that a Zn-MOF-PDMS chiral porous liquid material of the present invention can preferentially bind one enantiomer relative to the other enantiomer when in contact with a mixture of enantiomers. Therefore, the chiral porous material of the present invention can be used in a resolution method.

[0019] In another aspect, a method of separating a mixture of enantiomers comprises passing a composition comprising the mixture of enantiomers through the above-described chromatographic column.

[0020] Furthermore, the method for separating the enantiomeric mixture comprises contacting a composition containing the enantiomeric mixture with the above-mentioned material. The enantiomeric mixture interacts with the Zn-MOF-PDMS porous liquid to different degrees, so that its retention time in the column is different, so that different components are separated after passing through the column.

[0021] Furthermore, the method for separating the enantiomeric mixture comprises the following steps:

[0022] S1. passing a composition comprising a mixture of enantiomers through a chromatographic column comprising the Zn-MOF-PDMS chiral porous liquid material according to claim 1 as a stationary phase;

[0023] S2. contacting the composition comprising the mixture of enantiomers with the Zn-MOF-PDMS chiral porous liquid material according to claim 1, so that the components in the composition reach equilibrium on the chromatographic column;

[0024] S3. Separate the enantiomeric mixture by utilizing the different retention times of the components on the chromatographic column.

[0025] The Zn-MOF-PDMS chiral porous liquid materials can be used to separate a wide range of enantiomers with different structures. They can be used to separate racemic mixtures or compositions in which one enantiomer is present in excess. They are particularly useful for separating enantiomers of chiral compounds from epoxides, aldehydes, alcohols, esters and ketones.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The Zn-MOF-PDMS chiral porous liquid material of the present invention has the characteristics of both chiral porous solid materials and liquid materials, has good stability and film-forming properties, is very suitable for preparing capillary gas chromatography columns by static method, has low column preparation cost, good column preparation reproducibility, and the synthetic raw materials are easily available and the synthetic method is relatively simple;

[0028] (2) The chiral porous liquid capillary gas chromatography column of the present invention exhibits high enantioselectivity and excellent chiral separation performance, and can separate various types of racemic compounds including epoxides, aldehydes, alcohols, esters and ketones;

[0029] (3) The chromatographic column of the present invention has the characteristics of fast separation speed, good resolution effect, good stability, and can be repeatedly used. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of the synthesis of the Zn-MOF-PDMS chiral porous liquid material used in the present invention;

[0031] Figure 2 The inner wall and cross-section scanning electron microscope images of the chromatographic column prepared by the present invention;

[0032] Figure 3 The chromatogram is a repeatability and stability test chromatogram of the chromatographic column of the present invention;

[0033] Figure 4 The chromatogram is a separation chromatogram of some chiral compounds using the chromatographic column of the present invention. DETAILED DESCRIPTION

[0034] In order to make those skilled in the art better understand the technical scheme of the present invention, the present invention is described in detail below in conjunction with specific embodiments. The experimental methods for which specific conditions are not indicated in the following examples are usually carried out under normal conditions or according to the conditions recommended by the manufacturer. The test materials used in the following examples, unless otherwise specified, are purchased from conventional biochemical reagent stores. Unless otherwise specified, percentages and parts are calculated by weight. Unless otherwise defined, all professional and scientific terms used in the text have the same meaning as those familiar to those skilled in the art. In addition, any method and material similar to or equal to the recorded content can all be applied to the present invention. The preferred implementation methods and materials described in the text are only for demonstration purposes.

[0035] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0036] The inventors constructed a metal organic framework Zn-MOF, and then reacted Zn-MOF with PDMS to synthesize type I chiral porous material Zn-MOF-PDMS (synthesis route see Figure 1 ) was used as the gas chromatography stationary phase to prepare a chiral porous liquid capillary gas chromatography column, which has good separation performance and enantiomeric selectivity for many different types of chiral compounds.

[0037] Example 1 Preparation of Zn-MOF-PDMS Chiral Porous Liquid Material

[0038] 0.1 g of D-histidine was weighed and dissolved in 53 mL of a mixed solution of deionized water / methanol (8 mL / 45 mL, V / V). Subsequently, 0.4 g of 2-methylimidazole and 0.36 g of Zn(NO 3 ) 2 6H 2 O were dissolved in D-histidine solution respectively; the two mixed solutions were poured into a 100 mL double-necked flask under stirring, reacted at 25 °C for 1 day, washed with methanol several times and vacuum dried to obtain white powder Zn-MOF;

[0039] 0.4 g Zn-MOF was dispersed in 15 mL toluene and ultrasonicated for 10 min. Then 4.0 g PDMS was added to the Zn-MOF toluene solution and stirred at 100 °C for 5 h. After the reaction was completed, the mixed solution was stirred at 80 °C to remove toluene and then vacuum dried at 80 °C to obtain the chiral porous liquid material Zn-MOF-PDMS.

[0040] Example 2 Preparation of chromatographic column

[0041] Take a quartz capillary column with a length of 15m and an inner diameter of 0.25mm, first rinse the capillary column with 1.0mol / L NaOH solution for 2 hours, then rinse the capillary column with ultrapure water until it is neutral, then rinse the capillary column with HCl (0.1mol / L) solution for 2 hours, and rinse it again with ultrapure water until it is neutral. Finally, connect one end of the capillary column to the injection port of the gas chromatograph, pass nitrogen gas and dry it at 120℃ for 6 hours to obtain a capillary column with a roughened inner wall;

[0042] The chiral porous liquid material Zn-MOF-PDMS prepared in Example 1 was dissolved in methanol to prepare a 3 mg / mL stationary phase solution, and the stationary phase solution was sucked into the capillary column using a vacuum system. When the stationary phase filled the entire capillary column, one end was then sealed with white latex. After the capillary column was placed for 3 days, the solvent was removed using a vacuum system in a constant temperature water bath at about 60°C to obtain a Zn-MOF-PDMS coated capillary column. Finally, the capillary column was aged: the temperature was increased from 30°C to 180°C at a heating rate of 3°C / min, and maintained for 2 hours under a nitrogen flow until the baseline of the chromatographic column was stable.

[0043] Example 3 Chromatographic separation effect test

[0044] The chromatographic separation effect of the chromatographic column on different types of racemic compounds was investigated. The chromatographic conditions were as follows: high-purity nitrogen as carrier gas, inlet temperature of 250°C, detector temperature of 250°C, split ratio of 40:1;

[0045] (a) n-butyl glycidyl ether, column temperature 190°C;

[0046] (b) Glycidol, column temperature 160°C;

[0047] (c) citronellal, column temperature 190 °C;

[0048] (d) β-citronellol, column temperature 200 °C;

[0049] (e) β-butyrolactone, column temperature 215 °C;

[0050] (f) 2-chlorocyclohexanone, column temperature 215°C;

[0051] (g) 1-methoxy-2-butanol, column temperature 170 °C;

[0052] (h) 1,2-butanediol, column temperature 190 °C;

[0053] (i) 1,3-Butanediol, column temperature 215 °C;

[0054] (j) methyl 2-bromopropionate, column temperature 160 °C;

[0055] (k) 1-(3-methylphenyl)ethanol, column temperature 170 °C;

[0056] (l) 1,2-propylene glycol, column temperature 190°C;

[0057] (m) 2,3-Butanediol, column temperature 215°C.

[0058] The results of separation of some racemic compounds by the chromatographic column are shown in Table 1.

[0059] Table 1

[0060]

[0061]

[0062] Depend on Figure 4 As can be seen from Table 1, the Zn-MOF-PDMS capillary gas chromatography column prepared in the present invention has a good chiral separation effect on many different types of racemic compounds including epoxy compounds, aldehydes, alcohols, esters and ketones.

[0063] Example 4

[0064] In order to study the stability and repeatability of the Zn-MOF-PDMS capillary gas chromatography column prepared in Example 2, glycidol was selected as the analyte for testing. To explore the repeatability of the Zn-MOF-PDMS coated column, the selected analytes were tested at the beginning of the column, after 200 injections, and after 300 injections. To study the stability of the Zn-MOF-PDMS column, glycidol was kept at 200°C for 3h and 8h for separation and analysis on the Zn-MOF-PDMS column. The separation chromatogram is shown in the attached figure. Figure 3 Chromatographic conditions: high-purity nitrogen as carrier gas, injection port temperature 250°C, detector temperature 250°C, split ratio 40:1, column temperature 160°C.

[0065] Depend on Figure 3 It can be seen that for the capillary chiral column prepared in Example 2, the retention time and peak shape of the three chromatograms did not change significantly when glycidol was just started to be used on the chromatographic column, after the chromatographic column had been injected 200 times, and after 300 times. The chromatograms obtained when the chromatographic column just started to be injected, when the chromatographic column was retained at 200°C for 3h, and when it was retained for 8h were compared, and it can be seen that the obtained chromatograms did not change, indicating that the Zn-MOF-PDMS capillary column has good reproducibility and thermal stability, and has good practical application prospects.

[0066] Finally, it should be noted that the above description is only a preferred embodiment of the present invention. Under the guidance of the present invention, those skilled in the art can make a variety of similar expressions without violating the purpose and claims of the present invention, and such changes all fall within the protection scope of the present invention.

Claims

1. A Zn-MOF-PDMS chiral porous liquid material, characterized in that: Prepared by the following steps: S1. Preparation of chiral Zn-MOF: D-histidine, 2-methylimidazole and Zn(NO3)2‧6H2O in a molar ratio of 1:(7-8):(1-2) were mixed, stirred and reacted at 25°C for 20-30h, and Zn-MOF was obtained after washing and vacuum drying; S2. Preparation of Zn-MOF-PDMS: Dissolve Zn-MOF and PDMS in a mass ratio of 1:(8-12) in toluene, and react at 95-105°C for 5 h. After the reaction, stir the mixture at 80°C, remove the toluene, and vacuum dry to obtain Zn-MOF-PDMS; its structure is shown in the following formula: Formula I.

2. Use of the Zn-MOF-PDMS chiral porous liquid material according to claim 1 as a gas chromatography stationary phase.

3. The use according to claim 2, characterized in that: Used to separate enantiomers.

4. The use according to claim 3, characterized in that: The enantiomers are derived from chiral compounds of the class of epoxides, aldehydes, alcohols, esters and ketones.

5. A chromatographic column, characterized in that: The Zn-MOF-PDMS chiral porous liquid material according to claim 1 is used as a stationary phase.

6. The method for preparing a chromatographic column according to claim 5, characterized in that: The following steps are involved: S1. Dissolve Zn-MOF-PDMS in methanol to prepare a 1-5 mg / mL stationary solution; S2. Etching the inner wall of the capillary column with an aqueous solution of alkali, washing the inner wall with water and then washing the inner wall with an aqueous solution of acid to neutralize the residual alkali, and then washing the inner wall of the capillary column with water until the pH value of the effluent is 7, so that the inner wall of the capillary column is roughened; S3. Fill the stationary liquid into the roughened capillary column and prepare it by static coating method.

7. A method for separating a mixture of enantiomers, the method comprising passing a composition comprising the mixture of enantiomers through a chromatographic column according to claim 5 or a chromatographic column prepared by the method according to claim 6.

8. A method of separating a mixture of enantiomers, the method comprising contacting a composition comprising the mixture of enantiomers with a material prepared from the material of claim 1.

9. The method according to claim 8, characterized in that The following steps are involved: S1. passing a composition comprising a mixture of enantiomers through a chromatographic column comprising a Zn-MOF-PDMS chiral porous liquid material according to claim 1 as a stationary phase; S2. contacting a composition comprising a mixture of enantiomers with a Zn-MOF-PDMS chiral porous liquid material according to claim 1, so that the components in the composition reach equilibrium on the chromatographic column; S3. Separate a mixture of enantiomers by taking advantage of the different retention times of the components on the chromatographic column.

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