Carbazole modified conjugated column [5] arene derivative and synthesis and application thereof in iodine adsorption separation

Abstract

The invention discloses a carbazole modified conjugated column [5] arene derivative, which is obtained by carrying out Suzuki coupling reaction on a carbazole compound with a pi conjugated group and column [5] arene. Compared with traditional unmodified ethyoxyl pillar [5] arene, the modified ethyoxyl pillar [5] arene has the advantages that a non-porous structure is converted into a porous structure, the specific surface area is greatly increased, a one-dimensional pore channel is also formed in a stacking mode, and the modified ethyoxyl pillar [5] arene can be used as a novel adsorption material to adsorb iodine, can adsorb iodine steam and can also adsorb iodine from an organic solvent or water. Compared with the previously reported iodine adsorption material, the carbazole modified ethyoxyl pillar [5] arene is very simple to synthesize, and the raw materials are very cheap; the iodine is easily dissolved in the organic solvent, so that the adsorbed iodine can be released in the organic solvent, and the iodine can be repeatedly used for multiple times. Therefore, the composite material is expected to be used as a novel adsorbent in the future for selective adsorption and separation of certain specific components in environments such as environmental pollutants, noble metals and nuclear wastes.

Description

Technical Field

[0001] The present invention relates to a conjugated column [5] aromatic hydrocarbon derivative and a synthesis method thereof. The present invention also relates to the application of the conjugated column [5] aromatic hydrocarbon derivative as an adsorption material in adsorption separation, belonging to the technical field of compound synthesis and the field of adsorption material. Background Art

[0002] As a clean and efficient energy source, nuclear power has attracted much attention in meeting the world's growing energy demand and carbon neutrality goals. However, since the accidents at the Fukushima nuclear power plant in Japan and the Chernobyl nuclear power plant in the Soviet Union, how to safely and effectively use nuclear energy has become the focus of attention of many scientific researchers. As radioactive waste, especially volatile and metabolism-related radioactive nuclides iodine. Among them, iodine (129) has a long radioactive half-life (1.57×10 7 Years), and in the nuclear industry production process, iodine (129) is a very common nuclear waste, so its adsorption and storage are very important. In addition, iodine (131) has a short half-life (8.02 days) and has side effects on human metabolism, and it should accumulate rapidly. Capturing iodine requires in-depth design of eco-friendly and economical materials. Most of the porous organic metal frameworks currently studied can also be used as iodine adsorption materials, but their relatively low thermal stability and humidity stability limit their practical application, because nuclear power plants contain a lot of water vapor and the temperature of volatile nuclear waste is usually relatively high. Therefore, the development of new adsorbents with high iodine capture capacity and strong chemical and thermal stability remains a challenge.

[0003] Pillarene, as a new class of supramolecular host compounds, has shown excellent results in host-guest chemistry. Many host-guest chemical systems have been well developed by modifying the structure of pillarene. Pillar[5]arene provides a good macrocyclic cavity structure, so it has a certain assembly ability and can be used to encapsulate small guest molecules. The present invention found through N2 adsorption isothermal test and cultured single crystal structure that carbazole-modified ethyl pillar[5]arene has changed from a non-porous structure to a porous structure compared with traditional unmodified fully ethoxy pillar[5]arene, and greatly increased the specific surface area. It also formed a one-dimensional pore in the stacking mode. Thermogravimetric test experiments also showed that it has good thermal stability and can be used as a new adsorption material to capture iodine. It can not only adsorb iodine vapor in the air, but also adsorb iodine from organic solvents or water. Compared with previously reported iodine adsorption materials, the synthesis of carbazole-modified ethoxy pillar[5]arene is very simple and the raw materials are relatively cheap, and the thermal stability is high; iodine is easily soluble in organic solvents, so the adsorbed iodine can be released in organic solvents, and it can be reused many times. Summary of the invention

[0004] The purpose of the present invention is to provide a carbazole-modified conjugated column [5] aromatic derivative and a synthesis method thereof; Another object of the present invention is to provide a carbazole-modified conjugated column [5] aromatic hydrocarbon derivative for use as an adsorption material in iodine capture.

[0005] 1. Carbazole modified column [5] aromatic derivatives and their synthesis methods The structural formula of the carbazole modified column [5] aromatic derivative is: The column[5]arene derivative is prepared by Suzuki coupling reaction of trifluoromethanesulfonate-modified column[5]arene (P5-OTf) with 4-(9H-carbazole-9-yl)phenylboronic acid to obtain a carbazole-modified conjugated column[5]arene derivative as a white solid, labeled as P5CBZ. The specific synthesis method is as follows: Synthesis of carbazole-modified conjugated column [5] aromatic derivative P5CBZ: Using toluene, ethanol and water as a mixed solvent, tetrakis(triphenylphosphine)palladium, lithium bromide and potassium carbonate as co-catalysts, the intermediate compound P5-OTf and 4-(9H-carbazole-9-yl)phenylboronic acid are refluxed at 95-105°C for 24-36 hours under nitrogen protection at a molar ratio of 1:2.0~1:2.4, dissolved in distilled water, extracted with dichloromethane, dried over anhydrous sodium sulfate, and the organic phase separated by column chromatography to obtain a white solid, which is the conjugated column [5] aromatic derivative P5CBZ.

[0006] The amount of tetrakis(triphenylphosphine)palladium used is 0.1 to 0.2 times the molar amount of the intermediate compound; the amount of lithium bromide used is 0.2 to 0.3 times the molar amount of the intermediate compound; the amount of potassium carbonate used is 8 to 12 times the molar amount of the intermediate compound. In the mixed solvent, the volume ratio of toluene, ethanol and water is 8:1:1.

[0007] The structural formula of column[5]arene trifluoromethanesulfonate (P5-OTf) is: Column [5] Aryl trifluoromethanesulfonate (P5-OTf) is from the literature: Adv. Mater. 2018, 30,1800177.

[0008] 2. Characterization of column[5] aromatic derivatives (1) Cultivation of single crystals Single crystals of the column[5]arene derivative P5CBZ were grown in dichloromethane solution and the crystal packing pattern was analyzed ( Figure 1 ). It was found that a one-dimensional pore was formed in the stacking mode, which achieved a transition from a non-porous structure to a porous structure compared to the traditional unmodified fully ethoxylated pentaaromatic hydrocarbons.

[0009] (2) Low temperature nitrogen adsorption-desorption isotherm test The crystal porosity of P5CBZ crystals and EtP5 crystals in N2 adsorption / desorption isothermal experiments at 77 K, the apparent BET surface area of ​​the two crystals, the pore distribution, pore contribution and pore volume of the crystals calculated by the BJH model were measured, and they were systematically compared. Through comparative analysis, it was found that compared with the traditional unmodified fully ethoxylated columnar[5]arene, the carbazole-modified ethoxylated columnar[5]arene achieved the transformation from a non-porous structure to a porous structure, and greatly increased the pore size, specific surface area, etc. ( Figure 2 ).

[0010] 3. Conjugated column [5] capture of iodine vapor by aromatic derivative P5CBZ 3.1 Solid vapor adsorption kinetics test Before the test, weigh the mass of a 2 mL empty bottle, take 5 mg of the activated macrocyclic P5CBZ and put it in a small bottle, then put it into a 10 mL sample bottle at 75 °C under normal pressure, and put 5 mg of iodine in the bottle. Every two hours, take out the small bottle, wipe the iodine off the bottle wall, and record the total mass of the small bottle and the macrocyclic after iodine adsorption on the electronic analytical balance. Repeat the operation until 24 hours, and it is found that the macrocyclic has been saturated with adsorption ( Figure 3 ).

[0011] 3.2 Heat loss analysis Before the thermogravimetric experiment, the conjugated column [5] aromatic derivative P5CBZ was activated by heating in vacuum at 80 °C. Then, 5 mg of the sample was placed in a 2 mL vial. The vial was opened and placed in a 5 mL vial containing 5 mg of iodine. The iodine vapor adsorption experiment was carried out at 75 °C ( Figure 4 ), after saturated adsorption, heat loss analysis was performed. The N2 flow rate was set to 40 mL / min, and the instrument was heated to 800 °C at 25 °C / min. The test found that there was no obvious weight loss at 25-400 °C. When the temperature was greater than 400 °C, it was the melting point / decomposition point of the macrocyclic P5CBZ, indicating that it has good thermal stability and is suitable for high temperature environments in nuclear power plants.

[0012] 3.3 Powder X-ray Diffraction In order to study the crystal structure transformation of the conjugated columnar [5]arene derivative P5CBZ before and after the adsorption of iodine vapor, we carried out powder X-ray diffraction analysis of its macrocycle before and after the adsorption of iodine vapor, such as Figure 5As shown in the figure, it can be clearly observed that the crystal structure of P5CBZ changes before and after the adsorption of iodine vapor, and the characteristic peaks of the macrocycle disappear completely (III-P5CBZ crystal before adsorption, IV-P5CBZ crystal after adsorption), confirming that the iodine element causes the macrocycle to lose its crystallinity and the good dispersion of iodine in the columnar [5] aromatic hydrocarbon. At the same time, it also indirectly explains the strong interaction between the iodine element and the columnar [5] aromatic hydrocarbon, which completely changes the crystal phase structure of the macrocycle through strong charge transfer.

[0013] 3.4 UV absorbance test in iodine aqueous solution First, prepare 1mmol / L iodine aqueous solution, dilute to 250 μmol / L and place in a 10ml vial. Take different weights of activated column [5] aromatic hydrocarbon P5CBZ and place in 250 μmol / L iodine aqueous solution. Add a magnetic bar and start stirring. After different time periods, test the absorbance of iodine water. The change in absorbance determines that P5CBZ has a good adsorption effect on iodine in the aqueous phase ( Figure 6 ).

[0014] 3.5. Cyclic experiment of adsorption efficiency of P5CBZ after adsorption of iodine vapor.

[0015] The stability of column [5] aromatic hydrocarbon P5CBZ after adsorption of iodine vapor was explored below. Figure 7 As shown, P5CBZ was first allowed to adsorb iodine vapor at 75 °C to reach a saturated state, and the total mass of the macrocycle and the adsorbed iodine vapor was recorded. It was then released in n-hexane solvent. The figure shows that I2@P5CBZ tends to be stable with increasing times. The weight loss is large in the first few times, which may be due to the escape of iodine molecules physically adsorbed on the surface. After the fourth time, the weight loss tends to be flat and reaches a basically stable state.

[0016] Beneficial effects of the present invention: 1. The carbazole-modified conjugated column [5] arene derivative of the present invention is obtained by Suzuki coupling reaction of a carbazole compound having a π conjugated group with column [5] arene. The conjugated column [5] arene derivative provides a good cavity structure that can enclose guest molecules of suitable size; through adsorption isothermal test and cultured single crystal structure, it is found that the carbazole-modified ethyl column [5] arene is transformed from a non-porous structure to a porous structure compared with the traditional unmodified fully ethoxy column [5] arene, and the specific surface area is greatly increased. A one-dimensional pore channel is also formed in the stacking mode, and it can be used as a new adsorption material to adsorb guest molecules of matching size. Thermogravimetric test experiments also show that it has good thermal stability and can be used as a new adsorption material to adsorb iodine.

[0017] 2. Conjugated pillar[5]arene derivatives can not only adsorb iodine vapor in the air, but also adsorb iodine from organic solvents or water. Compared with previously reported iodine adsorption materials, the synthesis of carbazole-modified ethyl pillar[5]arene is very simple, the raw materials are relatively cheap, and the thermal stability is high; iodine is easily soluble in organic solvents, so the adsorbed iodine can be released in organic solvents, and it can be reused many times.

[0018] 3. Compared with the traditional unmodified ethoxylated column[5]arene as adsorption material, due to the limitation of its small cavity, it can only capture a small amount of iodine. However, the molecular stacking cavity of column[5]arene modified with large π-conjugated group carbazole becomes larger and forms a one-dimensional channel, which greatly enhances the adsorption performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the crystal stacking pattern of P5CBZ.

[0020] Figure 2 This is a low temperature nitrogen adsorption-desorption isotherm test.

[0021] Figure 3 Solid vapor adsorption kinetics test.

[0022] Figure 4 For thermal gravimetric test.

[0023] Figure 5 Powder X-ray diffraction.

[0024] Figure 6 It is the UV absorbance test in iodine aqueous solution.

[0025] Figure 7 This is a cyclic experiment of the adsorption efficiency of P5CBZ after adsorbing iodine vapor.

[0026] Figure 8 This is the H NMR spectrum of the conjugated column 5 aromatic derivative. DETAILED DESCRIPTION

[0027] The synthesis of P5CBZ of the present invention and its application as an adsorption material in iodine capture are further described below through specific examples.

[0028] Example 1: Synthesis of conjugated column 5 aromatic derivative P5CBZ Triflate-modified column[5]arene P5-OTf (296 mg, 0.3 mmol), 4-(9H-carbazol-9-yl)phenylboronic acid (74 mg, 0.6 mmol), Pd(PPh3)4 (35 mg, 0.03 mmol), LiBr (13 mg, 0.05 mmol) and K2CO3 (276 mg, 2.0 mmol) were added to toluene / EtOH / H2O (4 mL / 0.5 mL / 0.5 mL) and heated at 100 °C for 36 h under N2 protection. The reaction mixture was then cooled to room temperature and poured into water (30 mL). After extraction with CH2Cl2, the combined organic phases were dried over Na2SO4. P5CBZ was obtained by silica gel column chromatography (petroleum ether / CH2Cl2 / ethyl acetate = 50:1:2, v / v / v) as a white solid (98 mg, 63%). 1 H NMR (400 MHz, Chloroform- d ) δ 8.18 – 8.10 (m, 4H), 7.53 – 7.37 (m, 14H), 7.33 – 7.17 (m, 14H), 6.72 (s, 2H), 6.61 (s, 2H), 6.50 (s, 2H), 5.96 (s, 2H), 4.02 (s, 2H), 3.92 (s, 2H), 3.79 – 3.55 (m, 21H), 3.47(s, 3H), 1.49 (s,3H), 1.18 (s, 4H), 1.13 (d, J = 5.3 Hz, 10H), 0.89 – 0.82 (m,11H) ( Figure 8 ).

[0029] Its synthetic route is as follows: Example 2: Iodine capture test of conjugated column [5] aromatic derivative P5CBZ.

[0030] Before the test, the masses of two 2 mL empty bottles were weighed in advance, and 5 mg of activated macrocyclic P5CBZ crystals and 5 mg of activated macrocyclic EtP5 crystals were taken out respectively, placed in two small bottles, and then placed in two 10 mL sample bottles at 75 °C under normal pressure. 5 mg of iodine was placed in each bottle. Every two hours, the small bottles were taken out and the iodine on the bottle wall was wiped clean. The total mass of the small bottles and the macrocyclic after iodine adsorption was recorded on the electronic analytical balance, and compared after adsorption to saturation. It was found that the traditional unmodified ethoxylated column [5] aromatic EtP5 crystal can only adsorb a very small amount of iodine, but after testing, it was found that the carbazole-modified The crystal of the conjugated column [5] aromatic derivative P5CBZ has an iodine adsorption capacity of up to 3.1 g / g. This is far higher than that of unmodified ethoxy column [5] aromatics. The heat loss analysis of the P5CBZ by thermogravimetric analysis showed that the heat loss after adsorbing iodine vapor to saturation was as high as 30.1%. In the powder X-ray diffraction analysis, it can be clearly observed that the crystal structure of P5CBZ changes before and after the adsorption of iodine vapor. The characteristic peaks of the macrocycle disappear completely. The single substance causes the macrocycle to lose its crystallinity and the good dispersion of iodine in the column [5] aromatics. The absorbance test in iodine aqueous solution also shows that P5CBZ has a good adsorption effect on iodine in aqueous solution.

Claims

1. A carbazole-modified conjugated column [5] aromatic derivative, the structural formula of which is: 。 2. The method for synthesizing the carbazole-modified conjugated column [5] aromatic derivative as claimed in claim 1, comprising the following process steps: using toluene, ethanol and water as a mixed solvent, tetrakis(triphenylphosphine)palladium, triphenylphosphine and potassium carbonate as a common catalyst, reacting column [5] aromatic trifluoromethanesulfonate and 4-(9H-carbazole-9-yl)phenylboronic acid at a molar ratio of 1:1 to 1:1.2 under nitrogen protection at 95 to 105°C for 24 to 36 hours, dissolving with distilled water, extracting with dichloromethane, drying with anhydrous sodium sulfate, and separating the organic phase by column chromatography to obtain a white solid as the target product, the carbazole-modified conjugated column [5] aromatic derivative; The structural formula of column [5] aromatic trifluoromethanesulfonate is: 。 3. The method for synthesizing the carbazole-modified conjugated column [5] aromatic derivative according to claim 2, characterized in that: The amount of tetrakis(triphenylphosphine)palladium used is 0.1 to 0.2 times the molar amount of column[5]aryl trifluoromethanesulfonate; the amount of triphenylphosphine used is 0.2 to 0.3 times the molar amount of column[5]aryl trifluoromethanesulfonate; and the amount of potassium carbonate used is 8 to 12 times the molar amount of column[5]aryl trifluoromethanesulfonate.

4. The method for synthesizing the carbazole-modified conjugated column [5] aromatic derivative according to claim 2, characterized in that: In the mixed solvent, the volume ratio of toluene, ethanol and water is 8:1:

1.

5. Use of the carbazole-modified conjugated column [5] aromatic derivative as adsorbent material in iodine capture as claimed in claim 1.

6. The use of the carbazole-modified conjugated column [5] aromatic derivative as an adsorption material in iodine capture as claimed in claim 5, characterized in that: Carbazole-modified conjugated columns[5]arene derivatives are used to adsorb iodine vapor or iodine in organic solvents or water.

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