Synthesis method of thieno [3, 2-b] thiophene-based fluorescent hydrogen bond organic framework material and application of thieno [3, 2-b] thiophene-based fluorescent hydrogen bond organic framework material in separation of toluene and methylcyclohexane

Abstract

The invention belongs to the technical field of hydrogen bond organic framework materials, and provides a synthesis method of a thieno [3, 2-b] thiophene-based fluorescent hydrogen bond organic framework material, which comprises the following steps: S1, ligand synthesis; the preparation method comprises the following steps: S1-1, synthesizing 2, 3, 5, 6-tetrabromo thieno [3, 2-b] thiophene; s1-2, synthesizing a compound 4, 4 ', 4' ', 4 '''-(2, 3, 5, 6-tetraphenyl thieno [3, 2-b] thiophene) tetracyano group by adopting a Suzuki-Mipu coupling reaction; and S2, carrying out single crystal synthesis to obtain the HOF-TT-1. The invention further discloses application of the fluorescent hydrogen bond organic framework material based on thieno [3, 2-b] thiophene in separation of methylbenzene and methylcyclohexane, HOF-TT-1 can efficiently adsorb and separate a mixed solution of methylbenzene and methylcyclohexane after being activated, the methylbenzene adsorption efficiency is 89.7%, reversible fluorescence change is accompanied, and the fluorescent hydrogen bond organic framework material has excellent thermal stability and acid-base stability, and can be used for preparing the fluorescent hydrogen bond organic framework material based on thieno [3, 2-b] thiophene. The material is a high-elasticity material capable of cyclically regenerating, adsorbing and separating a mixed solution of toluene and methylcyclohexane.

Description

Technical Field

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

[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 is mainly obtained by hydrogenating the corresponding aromatic hydrocarbons, so they have similar molecular structures and similar physical and chemical properties. The traditional distillation method is inefficient in this separation process and it is difficult to meet the growing industrial needs. Among them, toluene (Tol) and methylcyclohexane (MCH) are very important fine organic chemicals and organic solvents. Their boiling point difference is only 9℃, 110℃ and 101℃ respectively, which brings greater challenges to efficient separation. Therefore, researchers are eager to seek novel and efficient separation technologies. Among them, adsorption separation technology shows broad prospects. By applying porous materials, this method can not only improve 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 non-porous adaptive crystals have been widely studied and applied in adsorption separation. The unique properties of these materials make efficient separation possible and provide new solutions for the sustainable development of related industries.

[0003] In recent years, a new type of crystalline porous material, hydrogen-bonded organic frameworks (HOFs), has attracted much attention. They are mainly bonded by intermolecular hydrogen bonds, π-π stacking, electrostatic forces, van der Waals forces and other weak intermolecular interactions. They are favored by researchers because of their mild synthesis conditions, high crystallinity and solvent processability, easy repair and regeneration, and are widely used in gas adsorption and separation, proton conduction, heterogeneous catalysis, fluorescence and conduction. Among them, in the separation of mixed gases, they have been applied to the separation of CO2 / CH4, H2 / N2, Xe / Kr, C2H2 / C2H4, C2H2 / C2H6, etc. However, there are few HOFs that have been successfully applied to liquid separation. Among them, Liang et al. synthesized a hydrogen-bonded organic framework for benzene through a non-planar thiazine derivative with three cyano groups due to the electrostatic difference on the surface of benzene and cyclohexane, and achieved efficient adsorption and separation of benzene. However, there are still few hydrogen-bonded organic framework materials used for efficient adsorption and separation of Tol and MCH. Summary of the invention

[0004] In view of the technical problems existing in the above-mentioned hydrogen-bonded organic framework in liquid separation, the present invention proposes a synthesis method of a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene and its application in the separation of toluene and methylcyclohexane.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is that the present invention provides a method for synthesizing a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene, which specifically comprises the following steps:

[0006] S1, ligand synthesis;

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

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

[0009] S2, single crystal synthesis;

[0010] S2-1, dissolve the compound CN4TT synthesized in S1-2 in N,N-dimethylformamide, and add it into a Teflon hydrothermal synthesis reactor after ultrasonic vibration for 10-15 minutes;

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

[0012] S2-3. Obtain yellow needle-shaped crystals suitable for single crystal X-ray diffraction testing, namely HOF-TT-1.

[0013] Preferably, 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, stirred at room temperature for 30 minutes, heated to 78°C and refluxed overnight; after the reaction is completed, the temperature is cooled to room temperature, the mixture is washed with water and methanol, and vacuum dried to obtain a white solid Br4TT.

[0014] Preferably, in step S1-2, Br4TT, 4-cyanophenylboronic acid, cesium carbonate and tetrakis(triphenylphosphine)palladium are added to a three-necked flask, and a tetrahydrofuran solution is added and stirred to dissolve, and the mixture is heated to 75° C. and heated to reflux for 24 h under a nitrogen atmosphere; after the reaction is completed and cooled to room temperature, the organic solvent is removed under vacuum; 200 mL of deionized water is added, and the mixture is extracted with dichloromethane, and the extract is dried over anhydrous magnesium sulfate; after filtering, dichloromethane is removed under vacuum, and the crude product is purified by a chromatographic silica gel column to obtain CN4TT;

[0015] Preferably, in step S1-1, the volume ratio of glacial acetic acid and chloroform is 1:1 and both are 60 ml, the mass and molar volume of thieno[3,2-b]thiophene are 5 g and 35.7 mmol, respectively, and the mass and molar volume of liquid bromine are 28.1 g and 175.8 mmol, respectively; in step S1-2, the masses of Br4TT, 4-cyanophenylboronic acid, cesium carbonate and tetrakis(triphenylphosphine) are 1.0 g, 1.5 g, 2.4 g and 127 mg, respectively, and the molar volumes are 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 molar volume of CN4TT are 60 mg and 0.11 mmol, respectively, and the volume of N,N-dimethylformamide is 8 ml.

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

[0017] The present invention provides an application of a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene in the separation of toluene and methylcyclohexane. The hydrogen-bonded organic framework material has excellent thermal stability and acid-base stability and is a highly elastic material that can be recycled and regenerated to absorb and separate a mixed solution of toluene and methylcyclohexane.

[0018] Compared with the prior art, the advantages and positive effects of the present invention are:

[0019] 1. The present invention provides a method for synthesizing a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene. The method is simple and can synthesize a thieno[3,2-b]thiophene derivative CN4TT having four cyano groups. The presence of highly polar cyano groups makes the nitrogen atom carry a partial negative charge, thereby making it a hydrogen bond acceptor, which can not only form a strong interaction force with Tol, but also is conducive to the construction of a hydrogen bond framework, and the yield of the constructed HOF-TT-1 is greater than 70%.

[0020] 2. The present invention provides an application of a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene in the separation of toluene and methylcyclohexane. After activation, it can efficiently adsorb and separate a mixed solution of toluene and methylcyclohexane. The toluene adsorption efficiency is 89.7%, accompanied by reversible fluorescence changes. At the same time, the HOFs material has excellent thermal stability and acid-base stability, and is a highly elastic material that can be regenerated and adsorbed to separate a mixed solution of toluene and methylcyclohexane. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 The synthetic route of CN4TT provided by the present invention;

[0023] Figure 2 A schematic diagram of the synthesis of the hydrogen-bonded organic framework material HOF-TT-1 provided by the present invention;

[0024] Figure 3 is the asymmetric unit structure diagram of HOF-TT-1 of the present invention;

[0025] Figure 4 is the spatial topology diagram of HOF-TT-1 of the present invention;

[0026] Figure 5 is the powder diffraction pattern of HOF-TT-1 of the present invention;

[0027] Figure 6 This is an infrared spectrum diagram comparing HOF-TT-1 of the present invention with the ligand CN4TT;

[0028] Figure 7 Thermogravimetric diagram of HOF-TT-1 of the present invention;

[0029] Figure 8 It is the solid ultraviolet absorption and fluorescence emission diagram of HOF-TT-1 of the present invention;

[0030] Fig. 9 is a nitrogen specific surface area diagram of HOF-TT-1 of the present invention;

[0031] Fig.10 The fluorescence response diagram of toluene and methylcyclohexane of HOF-TT-1 of the present invention;

[0032] Fig.11 This is the mixed adsorption hydrogen spectrum of toluene and methylcyclohexane of HOF-TT-1 of the present invention;

[0033] Fig.12 This is the efficiency diagram of cyclic adsorption separation of toluene and methylcyclohexane mixed solution by HOF-TT-1 of the present invention;

[0034] Fig.13 This is the crystal data of HOF-TT-1 of the present invention. DETAILED DESCRIPTION

[0035] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict. For the convenience of description, if the words "upper", "lower", "left" and "right" appear below, they only indicate that the upper, lower, left and right directions are consistent with the accompanying drawings themselves, and do not limit the structure.

[0036] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.

[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 thieno[3,2-b]thiophene, which specifically comprises the following steps:

[0038] S1, ligand synthesis;

[0039] S1-1. Synthesize 2,3,5,6-tetrabromothieno[3,2-b]thiophene, i.e., Br4TT. Specifically, dissolve thieno[3,2-b]thiophene in a mixed solution of glacial acetic acid and chloroform, slowly drop bromine, stir at room temperature for 30 minutes, heat to 78°C and reflux overnight; after the reaction is completed, cool to room temperature, wash the mixture with water and methanol, and vacuum dry to obtain white solid Br4TT;

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

[0041] S2, single crystal synthesis;

[0042] S2-1, dissolve the compound CN4TT synthesized in S1-2 in N,N-dimethylformamide, and add it into a Teflon hydrothermal synthesis reactor after ultrasonic vibration for 10-15 minutes;

[0043] S2-2, heating the Teflon hydrothermal synthesis reactor at 120°C for 11-13 hours, and then slowly cooling it to room temperature within 11-13 hours;

[0044] S2-3. A yellow needle-shaped crystal suitable for single crystal X-ray diffraction testing, namely HOF-TT-1, was obtained and 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 60 ml, the mass and molar volume of thieno[3,2-b]thiophene are 5 g and 35.7 mmol, respectively, the mass and molar volume of liquid bromine are 28.1 g and 175.8 mmol, respectively, and the obtained product is 15 g Br4TT with a yield of 93.2%.

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

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

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

[0049] Based on the study of the surface electrostatic potential (ESP) distribution of Tol and MCH, due to the sp 2 The electronegativity of carbon atom is higher than that of sp 3 Carbon atoms make the hydrogen atoms in Tol carry more positive charges than those in MCH; the present invention provides a thieno[3,2-b]thiophene derivative (CN4TT) with four cyano groups, the presence of high-polarity cyano groups makes the nitrogen atom carry a partial negative charge, thereby making it a hydrogen bond acceptor, which can not only form a strong interaction force with Tol, but also is conducive to the construction of a hydrogen bond framework, and the yield of the constructed HOF-TT-1 is greater than 70%.

[0050] like Figure 3 - As shown in Figure 13, the present invention has fully studied the chemical structure and physical properties of HOF-TT-1:

[0051] like Figure 3As shown, the single crystal diffractometer used MoKα radiation (λ = 0.71073A). All data were integrated with SAINTv8.34A and non-absorption correction was performed using SADABS2014 / 5. The structure was solved by Bruker direct method and F2 was refined using SHELXL full matrix least squares. The asymmetric unit structure diagram was obtained using OLEX2.

[0052] like Figure 4 As shown, the cif file of HOF-TT-1 is imported into the diamond software and drawn.

[0053] like Figure 5 As shown, the PXRD test was performed using Shimadzu Lab X XRD-6000, and the X-ray source was a copper target ( Rigaku, D / max 2500PC) measured angles from 5° to 50°, and the obtained data was imported into Origin to obtain this figure.

[0054] like Figure 6 As shown, this figure was obtained by using a SHIMADZU IR AFFITY-1 infrared spectrometer and importing the data obtained from spectral-grade KBr pellets into Origin for comparison.

[0055] like Figure 7 As shown, using a ceramic crucible, the temperature was raised from room temperature to 800°C in a nitrogen atmosphere at a heating rate of 10°C / min. Under this condition, the thermal decomposition performance test was carried out. It can be seen from the figure that HOF-TT-1 loses guest molecules in the temperature range of 100-150°C. When the temperature rises to 400°C, the thermogravimetric curve quickly becomes very steep, the weight loss is obvious, and the material begins to collapse. After 620°C, the skeleton is completely decomposed. The measured data can be imported into Origin for plotting.

[0056] like Figure 8 As shown, the UV-visible diffuse reflectance spectrum was obtained by UV-2600 UV-visible spectrophotometer. The fluorescence emission spectrum was obtained by F-380A spectrophotometer. The measured data can be imported into Origin for plotting.

[0057] like Fig. 9 As shown, the specific surface area was tested using the Autosorb iQ surface analyzer. The HOF-TT-1 material was first immersed in 5 mL of ethanol solution, and the ethanol was replaced every 12 hours for a total of 5 times. The material was filtered and placed in an oven to dry. 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 capacity was 35 cm3 / g.

[0058] like Fig.10As shown in the figure, the fluorescence emission spectrum was obtained by F-380A spectrophotometer. The measured data can be imported into Origin for plotting.

[0059] like Fig.11 As shown, the 1H NMR spectra were obtained on a Bruker AVANCE III 500 (500 MHz) spectrometer. Fig.12 As shown, the 1H NMR spectra of five cycles of adsorption were obtained on a Bruker AVANCE III 500 (500 MHz) spectrometer and plotted using Origin. Fig.13 As shown, the Crystalline HOF-TT-1 tabular report was generated using FinalCif software.

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

[0061] Furthermore, the final constructed HOF-TT-1 has excellent thermal stability and acid-base stability. Through cyclic adsorption experiments, it was found that HOF-TT-1 is a highly elastic material that can be recycled and regenerated to adsorb and separate mixed solutions of toluene and methylcyclohexane. Therefore, the hydrogen-bonded organic framework material HOF-TT-1 is simple to synthesize, has high separation efficiency, and excellent cyclic renewability. It can be used for the separation and purification of other important hydrocarbons and has great application potential in chemical production and purification.

[0062] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for synthesizing a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene, comprising the steps of: S1, ligand synthesis; S2, single crystal synthesis; characterized in that: Step S1 and step S2 specifically include: S1-1, synthesis of 2,3,5,6-tetrabromothieno[3,2-b]thiophene, i.e. Br4TT; S1-2, using Suzuki-Miyaura coupling reaction to synthesize compound 4,4',4",4"'-(2,3,5,6-tetraphenylthieno[3,2-b]thiophene)tetracyano, i.e. CN4TT; S2-1, dissolve the compound CN4TT synthesized in S1-2 in N,N-dimethylformamide, and add it into a Teflon hydrothermal synthesis reactor after ultrasonic vibration for 10-15 minutes; S2-2, heating the Teflon hydrothermal synthesis reactor at 120°C for 11-13 hours, and then slowly cooling it to room temperature within 11-13 hours; S2-3. Obtain yellow needle-shaped crystals suitable for single crystal X-ray diffraction testing, namely HOF-TT-1.

2. A method for synthesizing a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene according to claim 1, characterized in that: 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, stirred at room temperature for 30 minutes, heated to 78°C and refluxed overnight; after the reaction is completed, the temperature is cooled to room temperature, the mixture is washed with water and methanol, and vacuum dried to obtain a white solid Br4TT.

3. The method for synthesizing a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene according to claim 2, characterized in that: In step S1-2, Br4TT, 4-cyanophenylboronic acid, cesium carbonate and tetrakis(triphenylphosphine)palladium are added to a three-necked flask, and tetrahydrofuran solution is added and stirred to dissolve, and the temperature is raised to 75°C and heated to reflux for 24 hours under a nitrogen atmosphere; after the reaction is completed and cooled to room temperature, the organic solvent is removed under vacuum; 200 mL of deionized water is added, extracted with dichloromethane, and the extract is dried over anhydrous magnesium sulfate; after filtering, dichloromethane is removed under vacuum, and the crude product is purified by chromatography on a silica gel column to obtain CN4TT.

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

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

6. Application of a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene in the separation of toluene and methylcyclohexane, characterized in that: According to the method for synthesizing a fluorescent hydrogen-bonded organic framework material based on thieno[3,2-b]thiophene according to claim 4, HOF-TT-1 has excellent thermal stability and acid-base stability. HOF-TT-1 is a highly elastic material that can be recycled and regenerated to adsorb and separate a mixed solution of toluene and methylcyclohexane.

Images