A diarylethene hydrogen-bonding organic framework single crystal, a synthesis method thereof and application thereof

Abstract

The application belongs to the technical field of hydrogen-bonded organic framework materials, and provides a diaryene hydrogen-bonded organic framework single crystal, a synthesis method thereof and application thereof, wherein the diaryene hydrogen-bonded organic framework single crystal is composed of 1,2-di[2-methyl-3-thiophenyl-5-pyridine] perfluorocyclopentene and tetrafluoro terephthalic acid, has good photochromic properties, has fast response and good reversibility, and overcomes the shortcomings of existing materials in the photochromic performance; the synthesis method is reasonable in design and simple in method, and is suitable for industrial scale production; the application of the diaryene hydrogen-bonded organic framework single crystal can efficiently separate a liquid mixture of pyridine and toluene, overcomes the problems of high energy consumption and complex operation in the traditional separation method, provides a low-energy-consumption, high-efficiency and environmentally-friendly separation solution, and is also suitable for the fields of environmental protection and fine chemical industry.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen-bonded organic framework materials technology, and particularly relates to a diarylene hydrogen-bonded organic framework single crystal, its synthesis method and its application. Background Technology

[0002] Organic solid-state photochromic materials, as important functional materials, are widely used in sensors, display technology, and stealth materials. Diarylenes have become a research hotspot due to their excellent photochromic properties. Especially in the design and regulation of molecular structure, there is still significant room for improvement in the photochromic performance of diarylene materials. Therefore, how to improve the performance of materials through rational molecular engineering design, particularly in regulating their photochromic behavior, remains a major challenge in the research of organic photochromic materials.

[0003] Hydrogen-bonded organic frameworks (HOFs), as an emerging class of functional materials, have shown broad application prospects in multiple fields due to their tunable molecular structure and high stability. Hydrogen bonding provides them with excellent self-assembly capabilities and structural control potential; however, the application of existing HOFs in photochromic materials is still immature. Although some studies have explored the photochromic properties of HOFs, the instability of intermolecular hydrogen bonding and their sensitivity to the external environment lead to insufficient stability and controllability in practical applications.

[0004] In the field of separation science, the separation of mixtures of pyridine and toluene is an important technology in chemical processes, widely used in fine chemicals, environmental protection, and other fields. Traditional separation methods, such as solvent extraction, distillation, and membrane separation, often suffer from high energy consumption, complex operation, and high cost, making it difficult to meet the growing demand for efficient separation. Summary of the Invention

[0005] This invention addresses the technical problems existing in the separation of mixtures of pyridine and toluene by proposing a diarylene hydrogen-bonded organic framework single crystal, its synthesis method, and its application. This invention can prepare materials that possess both excellent photochromic properties and potential separation applications, and exhibit good separation performance, high efficiency, and environmental friendliness in the separation of mixtures.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a diarylene hydrogen-bonded organic framework single crystal, its synthesis method and its application are provided by the present invention; wherein, the diarylene hydrogen-bonded organic framework single crystal is formed by assembling 1,2-di[2-methyl-3-thienyl-5-pyridine]perfluorocyclopentene (PDTE) and tetrafluoroterephthalic acid (TA); the diarylene hydrogen-bonded organic framework single crystal belongs to the monoclinic crystal system, the space group is C2 / c, and the cell parameters are a=21.437(8), b=8.418(3), c=19.277(7); α=90°, β=114.343(6)°, γ=90°;

[0007] The structural formula of the 1,2-bis[2-methyl-3-thienyl-5-pyridine]perfluorocyclopentene is:

[0008]

[0009] The structural formula of the tetrafluoroterephthalic acid is:

[0010]

[0011] This invention provides a method for synthesizing a single crystal of a diarylene hydrogen-bonded organic framework, comprising the following steps:

[0012] S1. A certain molar ratio of 1,2-bis[2-methyl-3-thienyl-5-pyridine]perfluorocyclopentene (PDTE) and tetrafluoroterephthalic acid (TA) is added to a 100mL single-necked flask. A certain volume of organic solvent is added to the flask, and the mixture is heated for a certain period of time until the raw materials are completely dissolved to obtain the reaction solution.

[0013] S2. After cooling the reaction solution to room temperature, filter it and transfer it into a 10mL glass vial. Seal the vial with plastic wrap and make a number of small holes in the plastic wrap with a syringe. Let it stand at room temperature for a period of time to evaporate, and obtain diarylene hydrogen-bonded organic framework single crystal PDTE-TA.

[0014] Preferably, in step S1, the molar ratio of 1,2-bis[2-methyl-3-thienyl-5-pyridine]perfluorocyclopentene to tetrafluoroterephthalic acid is 1:1.

[0015] Preferably, the organic solvent is anhydrous ethanol, and the volume of the organic solvent is 3-5 mL.

[0016] Preferably, in step S1, the heating temperature is 70°C and the heating time is 9 hours.

[0017] Preferably, the plastic wrap has 1-8 small holes with a diameter of less than 3 mm.

[0018] Preferably, the reaction solution is allowed to stand at room temperature for 9-14 days to evaporate.

[0019] The present invention provides an application of a diarylene hydrogen-bonded organic framework single crystal. The diarylene hydrogen-bonded organic framework single crystal is activated at 100°C for 8 hours to obtain an activated crystal. The activated crystal is used to separate polar and non-polar substances in a liquid mixture of polar and non-polar substances. The activated crystal is placed in the liquid mixture of polar and non-polar substances and the adsorption and separation of volatile gases are carried out at room temperature for 0-44 hours.

[0020] Preferably, the mixture of polar and nonpolar substances is a mixture of pyridine and toluene.

[0021] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0022] 1. The present invention provides a diarylene hydrogen-bonded organic framework single crystal. The diarylene hydrogen-bonded organic framework single crystal contains a diarylene structure with photo-switching properties during synthesis. The diarylene photochromic structural unit is not affected in the hydrogen-bonded organic framework and can still exhibit photochromic properties. It has fast response and good reversibility, overcoming the shortcomings of existing materials in photochromic performance.

[0023] 2. The present invention provides a method for synthesizing single crystals of diarylene hydrogen-bonded organic frameworks, which is reasonably designed and simple, and suitable for industrial-scale production.

[0024] 3. The application of a diarylene hydrogen-bonded organic framework single crystal provided by this invention can efficiently separate liquid mixtures of pyridine and toluene, overcoming the problems of high energy consumption and complex operation in traditional separation methods. It provides a low-energy, high-efficiency and environmentally friendly separation solution, and is also applicable to environmental protection, fine chemical industry and other fields. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a synthetic route diagram for PDTE-TA obtained in Example 1;

[0027] Figure 2 The crystal structure diagram of PDTE-TA obtained in Example 1 is shown.

[0028] Figure 3 Thermogravimetric analysis of PDTE-TA obtained in Example 1;

[0029] Figure 4The infrared spectrum of PDTE-TA obtained in Example 1;

[0030] Figure 5 The X-ray diffraction pattern of PDTE-TA obtained in Example 1;

[0031] Figure 6 The UV absorption spectrum of PDTE-TA prepared in Example 1 is shown.

[0032] Figure 7 The nitrogen gas adsorption diagram is shown for PDTE-TA prepared in Example 1.

[0033] Figure 8 The PDTE-TA prepared in Example 1 adsorbs pyridine and toluene vapors respectively. 1 H NMR;

[0034] Figure 9 The time-dependent solid-gas adsorption isotherm of PDTE-TA adsorption of pyridine and toluene mixed vapor obtained in Example 1;

[0035] Figure 10 The above is a gas chromatogram of the adsorption of pyridine and toluene mixed vapors by PDTE-TA prepared in Example 1.

[0036] Figure 11 This is a cyclic adsorption-regeneration diagram of the adsorption of pyridine and toluene mixed vapors by PDTE-TA prepared in Example 1. Detailed Implementation

[0037] 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.

[0038] 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.

[0039] Example 1, as Figure 1As shown, the present invention provides a method for synthesizing a single crystal of a diarylene hydrogen-bonded organic framework: S1, [1,2-bis[2-methyl-3-thienyl-5-pyridine]perfluorocyclopentene and tetrafluoroterephthalic acid in a 1:1 molar ratio are added to a 100 mL round-bottom flask, 4.0 mL of anhydrous ethanol solution is added to the round-bottom flask, and the mixture is heated to 70 °C and refluxed and stirred at this temperature for 9 h. After heating is stopped, a clear blue reaction solution is obtained.

[0040] S2. After cooling the reaction solution to room temperature, filter it and transfer it into a 10mL clean glass vial. Seal the vial with plastic wrap and poke 6 small holes in the plastic wrap with a syringe. Allow it to evaporate at room temperature for 9-14 days to obtain diarylene hydrogen-bonded organic framework single crystal PDTE-TA.

[0041] This invention conducted several measurements and experiments on PDTE-TA, specifically including the following measurements and experiments:

[0042] 1) Crystal measurement: Crystal measurement was performed on the PDTE-TA crystal material prepared in Example 1.

[0043] Test method: Measurements were performed at room temperature using a Bruker SMART APEX II single-crystal diffractometer, and refined using the SHELX-2014 program and full-matrix least squares method. All non-hydrogen atoms underwent anisotropic refinement. During the refinement process, disordered guest molecules were removed using the SQUEEZE program in PLATON.

[0044] like Figure 2 The PDTE-TA crystal structure diagram is shown. The diarylene hydrogen-bonded organic framework single crystal is assembled from 1,2-bis[2-methyl-3-thienyl-5-pyridine]perfluorocyclopentene and tetrafluoroterephthalic acid; the diarylene hydrogen-bonded organic framework single crystal belongs to the monoclinic crystal system, the space group is C2 / c, and the cell parameters are a=21.437(8), b=8.418(3), c=19.277(7); α=90°, β=114.343(6)°, γ=90°.

[0045] The structural formula of the 1,2-bis[2-methyl-3-thienyl-5-pyridine]perfluorocyclopentene is:

[0046]

[0047] The structural formula of the tetrafluoroterephthalic acid is:

[0048]

[0049] 2) Thermal stability test: The thermal stability of the PDTE-TA crystal material prepared in Example 1 was tested.

[0050] Test method: The thermal stability was investigated by heating from room temperature to 800℃ in a nitrogen atmosphere using a Netzsch STA 449C thermogravimetric analyzer at a heating rate of 10℃ / min.

[0051] like Figure 3 As shown, PDTE-TA underwent two mass losses, indicating that [1,2-bis[2-methyl-3-thienyl-5-pyridine]perfluorocyclopentene and tetrafluoroterephthalic acid decomposed, and were stable before decomposition at 200℃.

[0052] 3) Infrared spectroscopy test: The PDTE-TA crystal material prepared in Example 1 was subjected to infrared spectroscopy test.

[0053] Test method: Dry KBr was used to compress the sample into a tablet, and the infrared spectrum was recorded on a Bruker Vertex-70 Fourier transform infrared spectrometer in the wavenumber range of 4000-400 cm⁻¹. The infrared data of PDTE-TA, PDTE, and TA were compared.

[0054] like Figure 4 As shown, the change in the vibrational band of the -OH group (-COOH) in the PDTE-TA infrared spectrum indicates the formation of hydrogen bonds between PDTE and TA. Infrared spectroscopy verifies the formation of PDTE-TA crystals.

[0055] 4) X-ray diffraction test: X-ray diffraction test was performed on the PDTE-TA crystal material prepared in Example 1.

[0056] Test method: Powder X-ray diffraction (PXRD) characterization was performed at room temperature (5℃-50℃) in the 2θ range using Cu radiation on a Malvern Panalytical Empyrean X-ray diffractometer to determine the purity of the sample and whether the crystal structure has been altered.

[0057] like Figure 5 As shown, the spectra of the experimentally synthesized samples before and after illumination of the open-ring PDTE-TA-o and closed-ring PDTE-TA-c are in good agreement with the PXRD spectra simulated by Mercury single crystal data, indicating that the synthesized crystal PDTE-TA has high phase purity.

[0058] 5) Solid-state ultraviolet absorption spectroscopy test: The PDTE-TA crystal material prepared in Example 1 was subjected to solid-state ultraviolet absorption spectroscopy test.

[0059] Test Method: When testing the UV absorption spectrum of solid samples using the SHIMADZU UV-2700i, first prepare the sample and ensure it is clean and homogeneous. Then, use the reflectance attachment for measurement, selecting an appropriate spectral range (200-800 nm). Collect spectral data using reflectance mode during testing. After testing, convert the data from reflectance to absorption on the instrument, then export the data and plot it using Origin.

[0060] like Figure 6 As shown, the change in the absorption characteristics of PDTE-TA before and after ultraviolet light irradiation indicates that the material has undergone photochromism.

[0061] 6) Nitrogen gas adsorption experiment: Nitrogen gas adsorption experiment was performed on the PDTE-TA crystal material prepared in Example 1.

[0062] Test method: The sample was placed in an oven at 100℃ for 8 hours to complete the activation. After activation, the sample was placed in a gas adsorption device. Nitrogen gas adsorption-desorption test was performed to measure the nitrogen adsorption-desorption from open ring to closed ring before and after PDTE-TA light irradiation.

[0063] like Figure 7 As shown, the opening and closing of the rings in the diarylene leads to changes in the material's pore size and structure, causing the specific surface area to change from 6.073 m² / g to 15.970 m² / g. This indicates that the opening and closing of the rings in the material can significantly lead to changes in the gas specific surface area.

[0064] 7) Single-component vapor adsorption experiment: The PDTE-TA crystal material prepared in Example 1 was subjected to single-component vapor adsorption experiments of pyridine and toluene.

[0065] Test method: The sample was placed in an oven at 100℃ for 8 hours to complete the activation. The activated sample was then subjected to adsorption of single-component pyridine and toluene: 1 mL of pyridine was added to a 20 mL sealed glass vial, and 10 mg of the activated sample was placed in a 5 mL open glass vial. The 5 mL open glass vial was then placed in the 20 mL sealed glass vial containing the pyridine solution. 1 mL of toluene was added to a 20 mL sealed glass vial, and 10 mg of the activated sample was placed in the 5 mL open glass vial. The 5 mL open glass vial was then placed in the 20 mL sealed glass vial containing the toluene solution. The 1H NMR spectra of the adsorption of pyridine and toluene over time were monitored.

[0066] like Figure 8 As shown, by comparing the 1H NMR of PDTE-TA adsorbing pyridine and toluene respectively, it was found that PDTE-TA can adsorb about 2 pyridine molecules, while the adsorption of toluene is almost negligible. That is, the adsorption capacity of PDTE-TA for pyridine is significantly stronger than that for toluene.

[0067] 8) Two-component vapor adsorption experiment: The PDTE-TA crystal material prepared in Example 1 was subjected to a two-component vapor adsorption experiment of pyridine and toluene.

[0068] Test method: The sample was placed in an oven at 100℃ for 8 hours to complete the activation. The activated sample was then subjected to adsorption of a two-component mixture of pyridine and toluene (volume ratio 1:1): 1 mL of pyridine and 1 mL of toluene were added to a 20 mL sealed glass vial. 10 mg of the activated sample was placed in a 5 mL open glass vial. The 5 mL open glass vial was then placed in the 20 mL sealed glass vial containing the pyridine and toluene mixture. The 1H NMR spectroscopy of the adsorption of the pyridine and toluene mixture was monitored over time.

[0069] like Figure 9 As shown, the time-dependent solid-gas adsorption isotherm of PDTE-TA adsorbing a mixture of pyridine and toluene vapors reveals that PDTE-TA can adsorb approximately two pyridine molecules, while the adsorption of toluene is negligible, indicating that PDTE-TA has good adsorption selectivity for pyridine.

[0070] 9) Two-component gas chromatography test: The PDTE-TA crystal material prepared in Example 1 was subjected to two-component gas chromatography test of adsorbed pyridine and toluene.

[0071] Test method: The sample was placed in an oven at 100℃ for 8 hours to complete the activation. The activated sample was then subjected to adsorption of a two-component mixture of pyridine and toluene (volume ratio 1:1): 20 mL of sealed glass vial was taken, 2 mL of pyridine and 2 mL of toluene were added, and 50 mg of the activated sample was placed in a 5 mL open glass vial. The 5 mL open glass vial was then placed in the 20 mL sealed glass vial containing the pyridine and toluene mixture. Using a Trace1300 gas chromatograph, the adsorption content of pyridine and toluene in the sample after the adsorption of the pyridine and toluene mixture (volume ratio 1:1) reached saturation was measured.

[0072] like Figure 10 As shown, gas chromatography (GC) experiments determined that the proportion of pyridine in PDTE-TA was 97.4%, indicating that PDTE-TA has high adsorption selectivity and separation effect for pyridine.

[0073] 10) Repeated tests of adsorption of pyridine and toluene: In this example, repeated tests of adsorption of pyridine and toluene were conducted on the PDTE-TA crystal material prepared in Example 1 to study the repeatability of the material.

[0074] Test method: After PDTE-TA adsorbs a mixture of pyridine and toluene, the mixture can be removed by heating at 120℃ for 12 hours. The desorbed and recovered PDTE-TA can be used to repeat the experiment in step 9.

[0075] like Figure 11 As shown, the performance of PDTE-TA in separating a mixture of pyridine and toluene did not decrease after five recycling cycles. This indicates that the PDTE-TA material is sufficiently stable and can be reused.

[0076] Therefore, regarding the application of the diarylene hydrogen-bonded organic framework single crystal provided by the present invention, the activated diarylene hydrogen-bonded organic framework single crystal can be used to adsorb and separate pyridine and toluene in a liquid mixture of pyridine and toluene, and Experiment 9 shows that PDTE-TA has high adsorption selectivity and separation effect for pyridine.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A single crystal of a diarylene hydrogen-bonded organic framework, characterized in that, It is composed of 1,2-bis[2-methyl-3-thienyl-5-pyridine]perfluorocyclopentene and tetrafluoroterephthalic acid; the single crystal of the diarylene hydrogen-bonded organic framework belongs to the monoclinic crystal system, the space group is C2 / c, and the cell parameters are a = 21.437(8), b = 8.418(3), c = 19.277(7); α = 90°, β = 114.343(6)°, γ = 90°; The structural formula of the 1,2-bis[2-methyl-3-thienyl-5-pyridine]perfluorocyclopentene is: ； The structural formula of the tetrafluoroterephthalic acid is: 。 2. The method for synthesizing a single crystal of a diarylene hydrogen-bonded organic framework as described in claim 1, characterized in that, Includes the following steps: S1. A certain molar ratio of 1,2-bis[2-methyl-3-thienyl-5-pyridine]perfluorocyclopentene and tetrafluoroterephthalic acid is added to a 100 mL single-necked flask. A certain volume of organic solvent is added to the flask, and the mixture is heated for a certain period of time until the raw materials are completely dissolved to obtain a reaction solution. The molar ratio of 1,2-bis[2-methyl-3-thienyl-5-pyridine]perfluorocyclopentene to tetrafluoroterephthalic acid is 1:

1. The organic solvent is anhydrous ethanol, and the volume of the organic solvent is 3-5 mL. The heating temperature is 70°C, and the heating time is 9 h. S2. After cooling the reaction solution to room temperature, filter it and transfer it into a 10mL glass vial. Seal the vial with plastic wrap and poke a number of small holes in the plastic wrap with a syringe. Allow it to stand at room temperature for a period of time to evaporate. The time for the reaction solution to stand at room temperature to evaporate is 9-14 days to obtain a diarylene hydrogen-bonded organic framework single crystal PDTE-TA. The diarylene hydrogen-bonded organic framework single crystal PDTE-TA is a diarylene hydrogen-bonded organic framework single crystal as described in claim 1.

3. The method for preparing a single crystal of a diarylene hydrogen-bonded organic framework according to claim 2, characterized in that, The plastic wrap has 1-8 small holes, with a hole diameter of less than 3mm.

4. An application of a single crystal of a diarylene hydrogen-bonded organic framework, characterized in that, The single crystal of the diarylene hydrogen-bonded organic framework described in claim 1 is activated at 100°C for 8 hours to obtain an activated crystal, which is used to separate polar and nonpolar substances in a mixture of polar and nonpolar substances in a liquid.

5. The application of a single crystal of a diarylene hydrogen-bonded organic framework according to claim 4, characterized in that, The mixture of polar and nonpolar substances is a mixture of pyridine and toluene.

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