A method for preparing a high specific surface porous silica gel carrier by using water-soluble pillar[5]arene as a porogen and application thereof

Abstract

The application provides a method for preparing a high specific surface area porous silica gel carrier by using a water-soluble pillar[5]arene as a porogen and application thereof. The water-soluble pillar[5]arene is prepared by modifying a short-chain full-brominated pillar[5]arene with trimethylamine, and the water-soluble pillar[5]arene is used as a porogen to prepare a porous silica gel carrier with high specific surface area, narrow particle size and pore distribution range and stable performance by using tetraethyl orthosilicate as a silicon source by a template method, and a chromatographic column filled with the carrier realizes high-efficiency separation of phenylalanine and tryptophan. The porous silica gel carrier prepared by using the water-soluble pillar[5]arene as the porogen has a high specific surface area of 504 m 2 / g, the separation degree of phenylalanine and tryptophan reaches 1.41, and the porous silica gel carrier is extremely valuable in research in the application of chromatographic fillers in macromolecular separation or high-performance catalyst carrier.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of inorganic porous material preparation, and particularly relates to a method for preparing a high specific surface area porous silica gel carrier by using a water-soluble pillar[5]arene as a porogen, which is suitable for a biological macromolecule separation filler or a high-performance catalyst carrier. BACKGROUND

[0002] High specific surface area porous silica is widely used in separation analysis, chemical industry, catalysis and environmental protection due to its advantages such as high purity, low density, high specific surface area and many active silicon hydroxyl groups. In addition, high specific surface area porous silica has rich pore structure and active sites, and can improve the catalytic performance of reactions and is widely used in heterogeneous catalytic reactions. Common methods for synthesizing high specific surface area porous silica include sol-gel method, supercritical fluid drying method and template method. Among them, the silica is improved by using the template method, such as adding a new pore expander to further increase the pore size, porosity or specific surface area, so that the porous silica material with the pore structure, porosity or specific surface area required in many fields can be prepared.

[0003] Pillar[n]arene is a new generation of supramolecular macrocyclic oligomer, which has attracted widespread attention due to its highly symmetrical rigid structure and easy functionalization modification function. The water-soluble pillar[5]arene is a macrocyclic oligomer with a rigid framework and excellent electronic properties. The water-soluble pillar[5]arene prepared by functionalization modification of pillar[5]arene has great research and application value in the fields of catalytic materials, adsorption materials, separation materials and sensing materials. In view of this, the present application uses water-soluble supramolecular pillar[5]arene as a porogen to synthesize a new type of high specific surface area porous silica, which is expected to play an important role in the fields of biological macromolecule separation or new type of catalytic carrier. SUMMARY

[0004] The purpose of the present application is to provide a method for preparing a high specific surface area porous silica gel carrier by using water-soluble pillar[5]arene as a porogen and application thereof.

[0005] I. Preparation of high specific surface area porous silica gel carrier

[0006] (1) Synthesis of short-chain fully brominated pillar[5]arene: under the condition of normal pressure, room temperature and nitrogen atmosphere, bis(2-bromoethoxy)benzene, paraformaldehyde and boron trifluoride ether are dissolved in 1,2-dichloroethane, and stirred for 2-2.5 hours. After the reaction is completed, methanol is used for quenching, and column chromatography is used for purification to obtain short-chain fully brominated pillar[5]arene. The molar ratio of bis(2-bromoethoxy)benzene, paraformaldehyde and boron trifluoride ether is 1: (0.5-1.0): (0.5-1.0).

[0007] The synthesis route of short-chain fully brominated pillar[5]arene is as follows:

[0008]

[0009] (2) Synthesis of water-soluble pillar[5]arene: short-chain perbrominated pillar[5]arene was dispersed in anhydrous acetone, and a solution of trimethylamine in ethanol was added. The mixture was refluxed at 75-80 °C for 10-12 h. After distillation under reduced pressure, the water-soluble pillar[5]arene was obtained after washing. The molar ratio of short-chain perbrominated pillar[5]arene to trimethylamine was 1:10-1:15.

[0010] The synthetic route is as follows:

[0011]

[0012] (3) Preparation of porous silica gel carrier: water-soluble pillar[5]arene was mixed with ammonia, cyclohexane, and tert-butanol as a porogen, and tetraethyl orthosilicate was added as a silicon source. The mixture was stirred at 40-50 °C and 300-400 rpm for 10-12 h. After washing, drying, and calcination, a high specific surface area porous silica gel carrier was obtained. The porous silica gel was then dispersed in 50 mL of toluene, and 1.0 mL of 8-(trimethoxysilyl)octylamine was added. After mechanical stirring at 100 °C for 12 h, the mixture was packed into a 25 cm chromatographic column for high-performance separation of amino acids. The mass ratio of water-soluble pillar[5]arene to tetraethyl orthosilicate was 1:2-1:5, and the volume ratio of water, cyclohexane, and tert-butanol was 1:(1-2):(0.1-0.2).

[0013] II. Structural characterization

[0014] NMR of short-chain perbrominated pillar[5]arene 1 The H NMR resonance spectrum is shown in Figure 1. The peak at 6.91 ppm is the benzene ring H of short-chain perbrominated pillar[5]arene, the peak at 4.23 ppm is the methylene H adjacent to oxygen in the alkyl chain, and the peak at 3.84 ppm is the benzene ring bridging methylene H, indicating the successful synthesis of short-chain perbrominated pillar[5]arene. 1 H NMR (400 MHz, CDCl3, rt), δ(ppm): 6.91 (s, 10H), 4.23(t, 20H), 3.84(s, 10H), 3.63 (t, 20H). NMR of water-soluble pillar[5]arene 1 The H NMR resonance spectrum is shown in Figure 2. The peak at 6.84 ppm is the benzene ring H of short-chain perbrominated pillar[5]arene, the peak at 4.35-4.48 ppm is the methylene H adjacent to O in the alkyl chain, the peak at 3.70-3.82 ppm is the methylene H adjacent to N in the alkyl chain, and the peak at 3.22 ppm is the benzene ring bridging methylene H, and the peak at 3.11 ppm is the methyl H, indicating the successful synthesis of water-soluble pillar[5]arene. 1H NMR (400 MHz, D2O, rt), δ (ppm): 6.84 (s, 10H), 4.35~4.48 (d, 20H), 3.70~3.82 (d, 20H), 3.22 (s, 10H), 3.11 (s, 90H).

[0015] The infrared spectrum of water-soluble pillar[5]arene is shown in Figure 3 -1 The strong absorption peak is the C-H stretching vibration in the alkyl chain, 1574 cm -1 is the C=C stretching vibration peak of the benzene ring, 1460 cm -1 is the bending vibration of N-CH3, 1232 cm -1 The wide band is the C-N bond stretching vibration, 806 cm -1 is the vibration peak of the polysubstituted benzene ring, 731 cm -1 is the alkyl chain plane rocking vibration peak, and the infrared characterization confirms the successful preparation of water-soluble pillar[5]arene.

[0016] The morphology of the high specific surface area porous silica gel carrier prepared under the above optimal conditions with water-soluble pillar[5]arene as the pore-forming agent was characterized by scanning electron microscopy Figure 4 ), and it was found that the high specific surface area porous silica gel carrier prepared with water-soluble pillar[5]arene as the pore-forming agent showed a spherical morphology with a particle size of 3~5 µm, and further screening could obtain silica gel carriers of specific size suitable for chromatographic or catalyst carrier materials.

[0017] The N2 adsorption / desorption isotherm and pore size distribution of the high specific surface area porous silica gel carrier are shown in Figure 5 、 Figure 6 , which shows that the prepared material high specific surface area porous silica gel carrier has a mesoporous structure. The specific surface area is as high as 504 m 2 / g, and the pore size and porosity are high, which has good application prospect.

[0018] III. Separation performance as chromatographic packing material

[0019] The above high specific surface area porous silica gel carrier (5.0 g) prepared with water-soluble pillar[5]arene as the pore-forming agent was dispersed in 50 mL of methanol, and 300 mL of chromatographic methanol was used as the displacement liquid. The empty tube column with a length and pore size of 250 mm*4.6 mm was filled under a pressure of 45 MPa for 30 min to prepare a high specific surface area porous silica gel chromatographic column. Under the conditions of a mobile phase of methanol:water=80:20 by volume ratio, a detection wavelength of 254 nm, and a flow rate of 1.0 mL / min, good separation of phenylalanine and tryptophan was achieved Figure 7 ). ​

[0020] In summary, the present application prepares water-soluble pillar[5]arene by modifying the whole brominated pillar[5]arene with trimethylamine, and prepares a porous silica gel carrier with high specific surface area, particle size and narrow pore distribution range and stable performance by using the water-soluble pillar[5]arene as a porogen and tetraethyl orthosilicate as a silicon source template. The present application uses the water-soluble pillar[5]arene as a porogen template and tetraethyl orthosilicate as a silicon source, which overcomes the problem of insufficient specific surface area when using traditional small molecules or long alkyl chain molecules as a porogen to prepare porous microspheres with large pore size and specific surface area. The porous SiO2 prepared by the method has good morphology, high specific surface area up to 504 m 2 / g, narrow pore size (13 nm) and particle size (3-5 µm) distribution range, large pore volume (1.68 cm 3 / g), and the separation degree of phenylalanine and tryptophan reaches 1.41, which is expected to play an important role in the application of chromatographic packing in the separation of biomacromolecular proteins, serum and other target objects or high-performance catalyst carriers. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 NMR spectrum of short-chain whole brominated pillar[5]arene 1 H NMR resonance spectrum

[0022] Figure 2 NMR spectrum of water-soluble pillar[5]arene 1 H NMR resonance spectrum

[0023] Figure 3 Infrared spectrum of water-soluble pillar[5]arene

[0024] Figure 4 Scanning electron microscope of high specific surface area porous silica gel carrier

[0025] Figure 5 N2 adsorption / desorption isotherm of high specific surface area porous silica gel carrier

[0026] Figure 6 Pore size distribution of high specific surface area porous silica gel carrier

[0027] Figure 7 Chromatographic separation of high specific surface area porous silica gel DETAILED DESCRIPTION

[0028] The present application will be described in detail below through specific embodiments.

[0029] Example 1

[0030] (1) Synthesis of short-chain perbromo pillar[5]arene: Dissolve bis(2-bromoethoxy)benzene (3.5 g, 10 mmol) into 100 mL dry 1, 2-dichloroethane solution under normal pressure and room temperature in nitrogen atmosphere, then add polyformaldehyde (1.8 g, 10 mmol), boron trifluoride etherate (4.0 g, 10 mmol), mechanically stir for 2 hours, then add 120 mL methanol to quench. Dissolve the obtained residue in 200 mL chloroform, then remove the organic solvent under vacuum. Separate the solid by column chromatography with petroleum ether: dichloromethane = 10:1 to obtain short-chain perbromo pillar[5]arene.

[0031] (2) Synthesis of water-soluble pillar[5]arene: Disperse short-chain perbromo pillar[5]arene (1.8 g, 10 mmol) into 100 mL anhydrous acetone, add 10 mL trimethylamine (6 g, 0.1 mol) ethanol solution, reflux at 75 ℃ for 10 h, then distill off the solvent under reduced pressure, wash the solid with 50 mL acetone for 2 times to obtain water-soluble pillar[5]arene;

[0032] (3) Preparation of high specific surface area porous silica gel carrier: Add 0.4 g pore-forming water-soluble pillar[5]arene, 20 mL ammonia water, 30 mL cyclohexane and 2.0 mL tert-butyl alcohol into a round-bottom flask in sequence, stir for 30 minutes, then add 1.0 mL tetraethyl orthosilicate. Stir at a rotation speed of 400 rpm and a temperature of 50 ℃ for 12 hours. After the reaction is completed, the solid is obtained by suction filtration, washed with 100 mL deionized water for 3 times, dried in a 50 ℃ oven for 12 hours, then calcined at 500 ℃ in a muffle furnace for 2-3 hours to obtain a white powder, which is the high specific surface area porous silica gel carrier. The specific surface area is 216 m 2 / g, the average pore size is 7.8 nm, and the pore volume is 0.34 cm 3 / g.

[0033] Disperse the high specific surface area porous silica gel carrier prepared above in 50 mL toluene, add 1.0 mL of 8-(trimethoxysilyl)octylamine, mechanically stir at 100 ℃ for 12 h, then pack a 25 cm chromatographic column. Under the conditions that the mobile phase is methanol: water = 80:20 by volume ratio, the detection wavelength is 254 nm, and the flow rate is 1.0 mL / min, the chromatographic separation of phenylalanine and tryptophan is carried out, the retention time of phenylalanine is 11.2 min, the retention time of tryptophan is 12.8 min, the separation factor of phenylalanine and tryptophan is 1.14, and the resolution reaches 1.23.

[0034] Example 2

[0035] Steps (1) and (2) are the same as in Example 1.

[0036] (3) Preparation of high specific surface area porous silica gel carrier: 0.4 g of water-soluble pillar[5]arene porogenic agent, 20 mL of ammonia water, 30 mL of cyclohexane and 2.0 mL of tert-butyl alcohol were sequentially added to a round-bottom flask, and 2.0 mL of tetraethyl orthosilicate was added after stirring for 30 minutes. Stirring was performed at a rotation speed of 400 rpm and a temperature of 50°C for 12 hours. After the reaction was completed, the solid was washed with 100 mL of deionized water for 3 times, dried in an oven at 50°C for 12 hours, and then calcined at 500°C in a muffle furnace for 2-3 hours to obtain a white powder, which was the high specific surface area porous silica gel carrier. The specific surface area was 303 m 2 / g, the average pore size was 8.1 nm, and the pore volume was 0.59 cm 3 / g.

[0037] The high specific surface area porous silica gel carrier prepared above was dispersed in 50 mL of toluene, 1.0 mL of 8-(trimethoxysilyl)octylamine was added, and mechanical stirring was performed at 100°C for 12 hours, and then a 25 cm chromatographic column was packed. The retention time of phenylalanine was 10.5 min, the retention time of tryptophan was 12.2 min, the separation factor of phenylalanine and tryptophan was 1.16, and the resolution reached 1.36.

[0038] Example 3

[0039] Steps (1) and (2) were the same as in Example 1.

[0040] 0.8 g of water-soluble pillar[5]arene porogenic agent, 20 mL of ammonia water, 30 mL of cyclohexane and 2.0 mL of tert-butyl alcohol were sequentially added to a round-bottom flask, and 2.0 mL of tetraethyl orthosilicate was added after stirring for 30 minutes. Stirring was performed at a rotation speed of 400 rpm and a temperature of 50°C for 12 hours. After the reaction was completed, the solid was washed with 100 mL of deionized water for 3 times, dried in an oven at 50°C for 12 hours, and then calcined at 500°C in a muffle furnace for 2-3 hours to obtain a white powder, which was the high specific surface area porous silica gel carrier. The specific surface area was 504 m 2 / g, the average pore size was 13.0 nm, and the pore volume was 1.68 cm 3 / g.

[0041] The high specific surface area porous silica gel carrier prepared above was dispersed in 50 mL of toluene, 1.0 mL of 8-(trimethoxysilyl)octylamine was added, and mechanical stirring was performed at 100°C for 12 hours, and then a 25 cm chromatographic column was packed. The retention time of phenylalanine was 10.2 min, the retention time of tryptophan was 11.8 min, the separation factor of phenylalanine and tryptophan was 1.15, and the resolution reached 1.41.

Claims

1. A method for preparing a high specific surface area porous silica gel carrier using water-soluble columnar aromatics [5] as a pore-forming agent, characterized in that, Includes the following steps: (1) Synthesis of short-chain fully brominated aromatics[5]: Under normal pressure, room temperature and nitrogen atmosphere, bis(2-bromoethoxy)benzene, paraformaldehyde and boron trifluoride diethyl ether were dissolved in 1,2-dichloroethane and stirred for 2 to 2.5 hours. After the reaction was completed, the mixture was quenched with methanol and purified by column chromatography to obtain short-chain fully brominated aromatics[5]. (2) Synthesis of water-soluble column[5] aromatics: Short-chain fully brominated column[5] aromatics were dispersed in anhydrous acetone, and a trimethylamine ethanol solution was added. The mixture was refluxed at 75~80℃ for 10~12 hours, and then washed after vacuum distillation to obtain water-soluble column[5] aromatics. (3) Preparation of porous silica gel carrier: Water-soluble columnar aromatic hydrocarbons[5] were used as pore-forming agents and mixed with ammonia, cyclohexane and tert-butanol. Tetraethyl orthosilicate was added as a silicon source. The mixture was stirred and reacted at 40~50℃ and 300~400 rpm for 10~15 hours. After washing, drying and calcination, a high specific surface area porous silica gel carrier was obtained.

2. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of bis(2-bromoethoxy)benzene, paraformaldehyde, and boron trifluoride ether is 1:(0.5~1.0):(0.5~1.0).

3. The preparation method according to claim 1, characterized in that: In step (2), the molar ratio of short-chain fully brominated aromatic hydrocarbons [5] to trimethylamine is 1:10 to 1:

15.

4. The preparation method according to claim 1, characterized in that: In step (3), the mass ratio of water-soluble columnar aromatic hydrocarbons [5] to tetraethyl orthosilicate is 1:2 to 1:

5.

5. The preparation method according to claim 1, characterized in that: In step (3), the volume ratio of water, cyclohexane, and tert-butanol is 1:(1~2):(0.1~0.2).

6. The preparation method according to claim 1, characterized in that: In step (3), drying is performed at 50-55 ℃ for 10-15 hours; calcination is performed at 400-500 ℃ for 2-3 hours.

7. The application of the high specific surface area porous silica support prepared by the method according to any one of claims 1-6 in the separation of phenylalanine and tryptophan.

8. The application according to claim 7, characterized in that: Separation conditions for phenylalanine and tryptophan: The mobile phase was methanol:water = 80:20 (volume ratio), the detection wavelength was 254 nm, and the flow rate was 1.0 mL / min.

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