A synthesis method of a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene and application in toluene and methylcyclohexane separation

Abstract

The application belongs to the technical field of hydrogen-bonded organic framework materials, and proposes a synthesis method of a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene, which comprises S1, ligand synthesis; S1-1, synthesis of 2,3,5,6-tetrabromothieno[3,2-b]thiophene; S1-2, synthesis of compound 4,4',4'',4'''-(2,3,5,6-tetraphenylthieno[3,2-b]thiophene) tetracyano by using a Suzuki-Miyaura coupling reaction; S2, single crystal synthesis of HOF-TT-1. The application also includes an application of the fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene in separation of toluene and methylcyclohexane, and HOF-TT-1 can efficiently adsorb and separate a toluene and methylcyclohexane mixed solution after being activated, the adsorption efficiency of toluene is 89.7%, a reversible fluorescence change is accompanied, and the HOF-TT-1 has excellent thermal stability and acid-base stability, and is a high-elasticity material that can cyclically regenerate, adsorb and separate the toluene and methylcyclohexane mixed solution.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen-bonded organic framework materials, and particularly relates to a synthesis method of a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene and application thereof in separation of toluene and methylcyclohexane. BACKGROUND

[0002] In modern industry, the separation and purification of chemicals is the core link to ensure product quality and achieve efficient production. Among them, cycloaliphatic compounds are mainly obtained by hydrogenation of corresponding aromatic hydrocarbons, so they have similar molecular structures and similar physical and chemical properties. The traditional distillation method is low in efficiency in this separation process, and it is difficult to meet the growing industrial demand. Among them, toluene (Tol) and methylcyclohexane (MCH) are very important fine organic chemicals and organic solvents, and their boiling point difference is only 9℃, 110℃ and 101℃ respectively, which brings greater challenges to efficient separation. Therefore, researchers are urgently seeking novel and efficient separation technologies. Among them, adsorption separation technology shows broad prospects. By applying porous materials, this method not only improves the separation efficiency, but also has the advantages of energy saving, economy and environmental protection. At present, a variety of porous materials such as zeolites, metal-organic frameworks, covalent organic frameworks, porous organic polymers, porous organic cages and macrocyclic-based non-porous adaptive crystals have been widely studied and applied in adsorption separation. The unique properties of these materials make efficient separation possible, providing a new solution for the sustainable development of related industries.

[0003] In recent years, a new type of crystalline porous material, hydrogen-bonded organic framework (HOFs), has attracted much attention. It is mainly combined by intermolecular hydrogen bonds, π-π stacking, electrostatic forces, van der Waals forces and other intermolecular weak interaction forces. It is favored by researchers due to its advantages such as mild synthesis conditions, high crystallinity and solvent processability, easy repair and regeneration, and is widely used in gas adsorption separation, proton conduction, heterogeneous catalysis, fluorescence and conduction. Among them, in the separation of mixed gases, it has been applied to the separation of CO2 / CH4, H2 / N2, Xe / Kr, C2H2 / C2H4, C2H2 / C2H6, etc. However, there are fewer HOFs successfully applied in liquid separation. Among them, Liang et al. synthesized a hydrogen-bonded organic framework for efficient adsorption and separation of benzene by using a non-planar benzothiazine derivative with three cyano groups due to the difference in the surface electrostatics of benzene and cyclohexane. However, there are still few hydrogen-bonded organic framework materials for efficient adsorption and separation of toluene and methylcyclohexane. SUMMARY

[0004] The present application aims at the technical problems of the hydrogen-bonded organic framework in liquid separation, and provides a synthesis method of a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene and application thereof in separation of toluene and methylcyclohexane.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: the present application provides a synthesis method of a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene, which specifically comprises the following steps:

[0006] S1, synthesis of a ligand;

[0007] S1-1, synthesis of 2,3,5,6-tetrabromothieno[3,2-b]thiophene, i.e., Br4TT;

[0008] S1-2, synthesis of compound 4,4',4'',4'''-(2,3,5,6-tetraphenylthieno[3,2-b]thiophene) tetracyano, i.e., CN4TT, by using a Suzuki-Miyaura coupling reaction;

[0009] S2, single crystal synthesis;

[0010] S2-1, dissolving the compound CN4TT synthesized in S1-2 in N,N-dimethylformamide, and then adding the mixture into a Teflon hydrothermal synthesis reactor after ultrasonic oscillation for 10-15 min;

[0011] S2-2, heating the Teflon hydrothermal synthesis reactor at 120 DEG C for 11-13 h, and then slowly cooling the reactor to room temperature within 11-13 h;

[0012] S2-3, obtaining yellow needle-shaped crystals suitable for single crystal X-ray diffraction test, i.e., HOF-TT-1.

[0013] As a preferred, in step S1-1, thieno[3,2-b]thiophene is dissolved in a mixed solution of glacial acetic acid and chloroform, liquid bromine is slowly added dropwise, stirring is carried out at room temperature for 30 min, heating is carried out to 78 DEG C for reflux overnight; after the reaction is completed, the mixture is cooled to room temperature, the mixture is washed with water and methanol, and vacuum drying is carried out to obtain white solid Br4TT.

[0014] As a preferred, in step S1-2, Br4TT, 4-cyanophenylboronic acid, cesium carbonate and tetrakis(triphenylphosphine)palladium are added into a three-necked flask, and tetrahydrofuran solution is added for stirring and dissolving, heating is carried out to 75 DEG C under nitrogen atmosphere for reflux for 24 h; after the reaction is completed and the temperature is cooled to room temperature, the organic solvent is removed under vacuum; 200 mL of deionized water is added, extraction is carried out with dichloromethane, and the extraction liquid is dried with anhydrous magnesium sulfate; after filtration, dichloromethane is removed under vacuum, and the crude product is purified by using a chromatographic silica gel column to obtain CN4TT;

[0015] As preferred, in step S1-1, the volume ratio of glacial acetic acid and chloroform is 1:1 and both are 60ml, the mass and the amount of substance of thieno[3,2-b]thiophene are 5 g and 35.7 mmol respectively, and the mass and the amount of substance of liquid bromine are 28.1 g and 175.8 mmol respectively; in step S1-2, the mass of Br4TT, 4-cyanobenzenboronic acid, cesium carbonate and tetra(triphenylphosphine) palladium is 1.0 g, 1.5 g, 2.4 g and 127 mg respectively, and the amount of substance is 2 mmol, 0.6 mmol, 17.6 mmol and 0.11 mmol respectively, and the volume of tetrahydrofuran solution is 100ml; in S2-1, the mass and the amount of substance of CN4TT are 60 mg and 0.11 mmol respectively, and the volume of N,N-dimethylformamide is 8ml.

[0016] The application provides an application of a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene in separation of toluene and methylcyclohexane, the hydrogen-bonded organic framework material has cyanic fluorescence, can efficiently adsorb and separate a toluene and methylcyclohexane mixed solution after activation, the toluene adsorption efficiency is 89.7 %, and reversible fluorescence change is accompanied.

[0017] The application provides an application of a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene in separation of toluene and methylcyclohexane, the hydrogen-bonded organic framework material has excellent thermal stability and acid-base stability, and is a high-elasticity material that can cyclically regenerate, adsorb and separate a toluene and methylcyclohexane mixed solution.

[0018] Compared with the prior art, the application has the advantages and positive effects that:

[0019] 1. The application provides a synthesis method of a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene, the method is simple, and a thieno[3,2-b]thiophene derivative CN4TT with four cyano groups is synthesized, the existence of the high-polarity cyano group makes the nitrogen atom have a partial negative charge, so that the nitrogen atom becomes a hydrogen-bonded acceptor, which not only can form a strong interaction force with toluene, but also is beneficial to the construction of a hydrogen-bonded framework, and the yield of the constructed HOF-TT-1 is greater than 70%.

[0020] 2. The application provides an application of a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene in separation of toluene and methylcyclohexane, the hydrogen-bonded organic framework material can efficiently adsorb and separate a toluene and methylcyclohexane mixed solution after activation, the toluene adsorption efficiency is 89.7 %, and reversible fluorescence change is accompanied, and the HOFs material has excellent thermal stability and acid-base stability, and is a high-elasticity material that can cyclically regenerate, adsorb and separate a toluene and methylcyclohexane mixed solution. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following embodiments are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0022] Figure 1 A synthesis route map of CN4TT provided by the present application is shown in the following figure.

[0023] Figure 2 A synthesis schematic diagram of HOF-TT-1, the hydrogen-bonded organic framework material provided by the present application, is shown in the following figure.

[0024] Figure 3 A structure diagram of the asymmetric unit of HOF-TT-1 of the present application is shown in the following figure.

[0025] Figure 4 A space topology diagram of HOF-TT-1 of the present application is shown in the following figure.

[0026] Figure 5 A powder diffraction diagram of HOF-TT-1 of the present application is shown in the following figure.

[0027] Figure 6 An infrared spectrum diagram of HOF-TT-1 of the present application compared with ligand CN4TT is shown in the following figure.

[0028] Figure 7 A thermogravimetric diagram of HOF-TT-1 of the present application is shown in the following figure.

[0029] Figure 8 A solid ultraviolet absorption and fluorescence emission diagram of HOF-TT-1 of the present application is shown in the following figure.

[0030] Figure 9 A nitrogen specific surface area diagram of HOF-TT-1 of the present application is shown in the following figure.

[0031] Figure 10 A fluorescence response diagram of HOF-TT-1 of the present application to toluene and methylcyclohexane is shown in the following figure.

[0032] Figure 11 A mixed adsorption hydrogen spectrum diagram of HOF-TT-1 of the present application to toluene and methylcyclohexane is shown in the following figure.

[0033] Figure 12 An efficiency diagram of HOF-TT-1 of the present application in the cyclic adsorption separation of toluene and methylcyclohexane mixed solution is shown in the following figure.

[0034] Figure 13 Crystal data of HOF-TT-1 of the present application is shown in the following figure. DETAILED DESCRIPTION

[0035] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" appearing below only indicate that they correspond to the upper, lower, left, and right directions in the accompanying drawings and do not limit the structure.

[0036] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0037] Examples, such as Figure 1 and Figure 2 As shown, the present invention provides a method for synthesizing a fluorescent hydrogen-bonded organic framework material based on thiopheno[3,2-b]thiophene, which specifically includes the following steps:

[0038] S1, ligand synthesis;

[0039] S1-1. Synthesis of 2,3,5,6-tetrabromothiopheno[3,2-b]thiophene, i.e., Br4TT; specifically, thiopheno[3,2-b]thiophene is dissolved in a mixed solution of glacial acetic acid and chloroform, liquid bromine is slowly added dropwise, the mixture is stirred at room temperature for 30 min, heated to 78°C and refluxed overnight; after the reaction is completed, the mixture is cooled to room temperature, washed with water and methanol, and dried under vacuum to obtain a white solid Br4TT;

[0040] S1-2. The compound 4,4',4'',4'''-(2,3,5,6-tetraphenylthiopheno[3,2-b]thiophene)tetracyano, i.e., CN4TT, was synthesized by the Suzuki-Miyaura coupling reaction. Specifically, Br4TT, 4-cyanobenzonic acid, cesium carbonate, and tetra(triphenylphosphine)palladium were added to a three-necked flask, and tetrahydrofuran solution was added and stirred to dissolve. The mixture was heated to 75°C and refluxed for 24 hours under a nitrogen atmosphere. After the reaction was completed and cooled to room temperature, the organic solvent was removed under vacuum. 200 mL of deionized water was added, and the mixture was extracted with dichloromethane. The extract was dried over anhydrous magnesium sulfate. After filtration, the dichloromethane was removed under vacuum, and the crude product was purified by silica gel column chromatography to obtain CN4TT.

[0041] S2, Single crystal synthesis;

[0042] S2-1. Dissolve the compound CN4TT synthesized in S1-2 in N,N-dimethylformamide, sonicate for 10-15 min, and then add it to the Teflon hydrothermal synthesis reactor.

[0043] S2-2, heat the Teflon hydrothermal synthesis reactor at 120℃ for 11-13h, and then slowly cool to room temperature within 11-13h;

[0044] S2-3, obtain yellow needle-shaped crystals suitable for single crystal X-ray diffraction test, i.e. HOF-TT-1, which is characterized by single crystal X-ray crystallography.

[0045] More specifically, in step S1-1, the volume ratio of glacial acetic acid and chloroform is 1:1 and both are 60ml, the mass and amount of substance of thieno[3,2-b]thiophene are 5g and 35.7mmol respectively, the mass and amount of substance of liquid bromine are 28.1g and 175.8mmol respectively, and the obtained product 15g Br4TT has a yield of 93.2%.

[0046] In step S1-2, the mass of Br4TT, 4-cyanophenylboronic acid, cesium carbonate and tetra(triphenylphosphine) is 1.0g, 1.5g, 2.4g and 127mg respectively, and the amount of substance is 2mmol, 0.6mmol, 17.6mmol and 0.11mmol respectively, the volume of tetrahydrofuran solution is 100ml, and the obtained product is 0.9g CN4TT.

[0047] In S2-1, the mass and amount of substance of CN4TT are 60mg and 0.11mmol respectively, and the volume of N,N-dimethylformamide is 8ml.

[0048] In S2-3, the obtained product is 45mg HOF-TT-1 with a yield of 75%.

[0049] Based on the study of the surface electrostatic potential (ESP) distribution of Tol and MCH, since sp 2 The electronegativity of carbon atom is higher than that of sp 3 The hydrogen atom in Tol carries more positive charge than that in MCH; the thieno[3,2-b]thiophene derivative (CN4TT) provided by the application has four cyano groups, the existence of high-polarity cyano group makes the nitrogen atom carry partial negative charge, so as to become a hydrogen bond acceptor, which not only can form strong interaction force with Tol, but also is conducive to the construction of hydrogen bond framework, and the yield of constructed HOF-TT-1 is greater than 70%.

[0050] As Figure 3 As shown in 13, the chemical structure and physical properties of HOF-TT-1 are fully studied by the application:

[0051] As Figure 3The single crystal diffractometer used Mo Ka radiation (λ = 0.71073 A) as shown. All data were integrated using SAINT v8.34A and corrected for absorption using SADABS 2014 / 5. The structure was solved by direct methods using Bruker and refined on F2 using SHELXL full-matrix least squares. The asymmetric unit structure diagram was obtained by OLEX2.

[0052] As shown in Figure 4 The cif file of HOF-TT-1 was imported into diamond software to obtain the drawing.

[0053] As shown in Figure 5 The PXRD test was measured by Shimadzu Lab X XRD-6000, the X-ray source was copper target (λ = 1.5418 Å, Rigaku, D / max 2500 PC), the measurement angle was from 5° to 50°, and the obtained data was imported into Origin to obtain the figure.

[0054] As shown in Figure 6 The SHIMADZU IR AFFITY-1 infrared spectrometer was used, the data obtained by pressing KBr tablet was imported into Origin for plotting and comparison to obtain the figure.

[0055] As shown in Figure 7 The ceramic crucible was used, the temperature was increased from room temperature to 800℃ in nitrogen atmosphere, the heating rate was 10℃ / min, under this condition, the thermal decomposition performance test was carried out, from the figure, it can be seen that the guest molecules of HOF-TT-1 are lost in the temperature range of 100-150℃, when the temperature rises to 400℃, the thermogravimetric curve becomes very steep, the weight loss is obvious, the material begins to collapse, the skeleton is completely decomposed after 620℃, and the measured data is imported into Origin for plotting.

[0056] As shown in Figure 8 The UV-2600 ultraviolet visible spectrophotometer was used to obtain the ultraviolet visible diffuse reflectance spectrum. The F-380A spectrophotometer was used to obtain the fluorescence emission spectrum. The measured data was imported into Origin for plotting.

[0057] As shown in Figure 9 The Autosorb iQ specific surface area analyzer was used to test the specific surface area, first, the HOF-TT-1 material was soaked in 5 mL of ethanol solution, the ethanol was replaced every 12 hours, a total of 5 times, the material was filtered and placed in an oven for drying, and after activation treatment, it was used for nitrogen adsorption-desorption test. The measured BET specific surface area was 3.10 m2 / g, and the nitrogen adsorption amount was 35 cm3 / g.

[0058] As shown in Figure 10The fluorescence emission spectra were obtained by F-380A spectrophotometer. The measured data were imported into Origin for plotting.

[0059] As shown in FIG. 6, the 1H nuclear magnetic resonance spectrum was obtained on a Bruker AVANCE III 500 (500 MHz) spectrometer. Figure 11 As shown in FIG. 6, the 1H nuclear magnetic resonance spectrum was obtained on a Bruker AVANCE III 500 (500 MHz) spectrometer. Figure 12 As shown in FIG. 6, the 1H nuclear magnetic resonance spectrum was obtained on a Bruker AVANCE III 500 (500 MHz) spectrometer. Figure 13 As shown in FIG. 6, the 1H nuclear magnetic resonance spectrum was obtained on a Bruker AVANCE III 500 (500 MHz) spectrometer.

[0060] Through the experiment and analysis of the chemical structure and physical properties of the constructed HOF-TT-1, it is concluded that HOF-TT-1 has cyan fluorescence, has a significant fluorescence recognition ability for toluene after activation, can efficiently adsorb and separate toluene and methylcyclohexane mixed solution after activation, and through the solid vapor adsorption experiment, it is found that the efficiency of adsorbing and separating toluene is 89.7%, accompanied by reversible fluorescence change.

[0061] Further, the finally constructed HOF-TT-1 has excellent thermal stability and acid-base stability, and through the cycle adsorption experiment, it is found that HOF-TT-1 is a high-elasticity material that can cyclically regenerate and adsorb and separate toluene and methylcyclohexane mixed solution. Therefore, the hydrogen-bonded organic framework material HOF-TT-1 is simple in synthesis, high in separation efficiency, excellent in cyclic regeneration performance, and can be applied to the separation and purification of other important hydrocarbons, and has great application potential in chemical production purification.

[0062] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in other forms. Any skilled person in the art can modify or change the above disclosed technical content to equivalent embodiments applied to other fields, but any simple modification, equivalent change and modification made on the basis of the technical essence of the present application to the above embodiments still belongs to the protection scope of the present application.

Claims

1. A method for synthesizing a thieno[3,2-b]thiophene-based fluorescent hydrogen-bonded organic framework material, comprising steps of: S1, ligand synthesis; S2, single crystal synthesis; characterized in that, The step S1 and the step S2 further specifically comprise: S1-1, synthesizing 2,3,5,6-tetrabromothieno[3,2-b]thiophene, namely Br4TT; S1-2, synthesizing compound 4,4',4'',4'''-(2,3,5,6-tetraphenylthieno[3,2-b]thiophene) tetracyano, namely CN4TT, by using a Suzuki-Miyaura coupling reaction; S2-1, dissolving the compound CN4TT synthesized in S1-2 in N,N-dimethylformamide, and then adding the mixture into a Teflon hydrothermal synthesis reactor after ultrasonic oscillation for 10-15 min; S2-2, heating the Teflon hydrothermal synthesis reactor at 120 DEG C for 11-13 h, and then slowly cooling to room temperature within 11-13 h; S2-3, obtaining yellow needle-shaped crystals suitable for single crystal X-ray diffraction test, namely HOF-TT-1.

2. The method for synthesizing a fluorescent hydrogen-bonded organic framework material based on thiopheno[3,2-b]thiophene according to claim 1, characterized in that, In the step S1-1, thieno[3,2-b]thiophene is dissolved in a mixed solution of glacial acetic acid and chloroform, liquid bromine is slowly added dropwise, stirring is performed at room temperature for 30 min, heating is performed to 78 DEG C to reflux overnight, the mixture is washed with water and methanol after reaction is completed, and vacuum drying is performed to obtain white solid Br4TT.

3. The method for synthesizing a fluorescent hydrogen-bonded organic framework material based on thiopheno[3,2-b]thiophene according to claim 2, characterized in that, In the step S1-2, Br4TT, 4-cyanophenylboronic acid, cesium carbonate and tetrakis(triphenylphosphine)palladium are taken into a three-necked flask, and tetrahydrofuran solution is added to stir and dissolve, heating is performed to 75 DEG C to reflux for 24 h under a nitrogen atmosphere, the organic solvent is removed under vacuum after reaction is completed and cooling to room temperature, 200 mL of deionized water is added, extraction is performed with dichloromethane, the extraction liquid is dried with anhydrous magnesium sulfate, dichloromethane is removed under vacuum after filtration, and the crude product is purified by using a silica gel column to obtain CN4TT.

4. The method for synthesizing a fluorescent hydrogen-bonded organic framework material based on thiopheno[3,2-b]thiophene according to claim 3, characterized in that, In the step S1-1, the volume ratio of glacial acetic acid and chloroform is 1:1 and both are 60 ml, the mass and the amount of substance of thieno[3,2-b]thiophene are 5 g and 35.7 mmol respectively, and the mass and the amount of substance of liquid bromine are 28.1 g and 175.8 mmol respectively; in the step S1-2, the mass of Br4TT, 4-cyanophenylboronic acid, cesium carbonate and tetrakis(triphenylphosphine) is 1.0 g, 1.5 g, 2.4 g and 127 mg respectively, and the amount of substance is 2 mmol, 0.6 mmol, 17.6 mmol and 0.11 mmol respectively, and the volume of tetrahydrofuran solution is 100 ml; in S2-1, the mass and the amount of substance of CN4TT are 60 mg and 0.11 mmol respectively, and the volume of N,N-dimethylformamide is 8 ml.

5. Use of a thieno[3,2-b]thiophene-based fluorescent hydrogen-bonded organic framework material in the separation of toluene and methylcyclohexane, characterized in that, The HOF-TT-1 synthesized by the synthesis method of the thieno[3,2-b]thiophene-based fluorescent hydrogen-bonded organic framework material according to claim 4 has cyan fluorescence, can efficiently adsorb and separate a mixed solution of toluene and methylcyclohexane after being activated, the adsorption efficiency of toluene is 89.7 %, and is accompanied by reversible fluorescence change.

6. Use of a thieno[3,2-b]thiophene-based fluorescent hydrogen-bonded organic framework material in the separation of toluene and methylcyclohexane, characterized in that, The HOF-TT-1 synthesized according to the synthesis method of the thieno[3,2-b]thiophene-based fluorescent hydrogen-bonded organic framework material according to claim 4 has excellent thermal stability and acid-base stability, and the HOF-TT-1 is a high-elasticity material capable of cyclically regenerating and adsorbing and separating a mixture solution of toluene and methylcyclohexane.

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