A crystalline polymer containing quadruple hydrogen bonds and a preparation method thereof

Abstract

The present invention relates to a crystalline polymer containing quadruple hydrogen bonds and a preparation method thereof. Using 3,5-bis(ethyl benzoate) aniline and 2-amino-6-propyl-4[1H]pyrimidinone as raw materials, through a condensation reaction and a hydrolysis reaction, a dicarboxylic acid containing ureidopyrimidinone is obtained, and then through a crystallization method, a crystalline polymer is obtained. In the crystalline polymer, there is a strong quadruple hydrogen bond interaction between ureidopyrimidinone units. Compared with the prior art, the preparation method of the present invention has a simple process route, mild reaction conditions, high yield, and good repeatability. The crystalline polymer of the present invention has luminescent properties, and the maximum emission wavelength is 410 nm. The present invention has important theoretical significance for exploring crystalline polymers based on multiple hydrogen bonds and related properties, and also lays a foundation for the application of crystalline polymers containing multiple hydrogen bonds.

Description

Technical Field

[0001] The present invention belongs to the technical field of crystalline polymers and relates to a crystalline polymer containing quadruple hydrogen bonds and a preparation method thereof. Background Art

[0002] Crystalline materials are widely used in various fields of production and life and play a very important role. The chemical bonding methods often used to construct crystalline materials include covalent bonds, coordination bonds, and metal bonds, etc. Using hydrogen bonds as the main bonding method to construct crystalline materials, especially crystalline polymer materials, is a research field that has just developed in the past decade and is a research hotspot in the fields of chemistry and materials. Compared with other traditional bonding methods, the force of hydrogen bonds is weaker, but the reversibility of their bonding is stronger. Therefore, the crystalline polymers formed by hydrogen bond linkage have some unique advantages: such as the preparation method is simple, and they can be easily obtained through the natural evaporation of a saturated solution, the diffusion from a poor solvent to a good solvent, or the recrystallization process; the reversibility of hydrogen bonds improves the regeneration ability of the crystalline polymers prepared through them, and thus they have a certain structural self-healing ability; the crystalline polymers formed by hydrogen bond linkage do not contain metal elements and have better biocompatibility and lower cytotoxicity. These characteristics make the crystalline polymers formed by hydrogen bond linkage show broad application prospects in many fields such as gas storage / separation, catalysis, sensing, proton conduction, optoelectronic materials, and biomedicine.

[0003] When preparing crystalline polymers formed by hydrogen bond linkage, the strength of hydrogen bonds is an important factor that must be considered. It determines the structural stability of the crystalline polymers. The method of increasing the number of hydrogen bond linkages has been proven to play an important role in regulating the stability of crystalline materials. Arranging multiple hydrogen bonds between two functional modules will result in multiple hydrogen bonds with higher binding constants. Then, using organic modules containing multiple hydrogen bonds as structural units, crystalline polymers are further constructed through hydrogen bond interactions. The AADD-DDAA self-associating quadruple hydrogen bond is a very classic multiple hydrogen bond. In chloroform solution, its binding constant can be as high as 6×10 7 M -1 . Although the synthesis technology of molecular modules containing AADD-DDAA self-associating quadruple hydrogen bonds has been relatively mature, it has not been widely used in the construction of crystalline polymers. Therefore, starting from this point to explore crystalline polymers based on multiple hydrogen bonds and related properties has important theoretical significance and also lays a foundation for the application of crystalline polymers containing multiple hydrogen bonds. Summary of the Invention

[0004] The object of the present invention is to provide a crystalline polymer material containing quadruple hydrogen bonds and a preparation method thereof, which overcomes the above-mentioned defects. The stability of the crystalline polymer is achieved through the AADD-DDAA self-associating quadruple hydrogen bonds, the hydrogen bonds of multiple carboxyl groups, and the π-π stacking interaction of aromatic rings. The crystalline polymer has good thermal stability and great application potential in the field of fluorescent materials.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] The first object of the present invention is to provide a crystalline polymer containing quadruple hydrogen bonds. The structural unit of the crystalline polymer containing quadruple hydrogen bonds is 1-(1,3-bis(4-benzoic acid phenyl))-3-(6-propyl-4[1H]pyrimidinone-2-yl)urea; the 1-(1,3-bis(4-benzoic acid phenyl))-3-(6-propyl-4[1H]pyrimidinone-2-yl)urea includes a ureidopyrimidinone unit and a carboxyl group; dimers are formed by the AADD-DDAA self-associating quadruple hydrogen bonds between the ureidopyrimidinone units, and the dimers are further combined through the hydrogen bonds between the carboxyl groups to form the crystalline polymer containing quadruple hydrogen bonds.

[0007] Furthermore, the ureidopyrimidinone unit adopted in the present invention not only has a high self-association constant, but also has a rigid planar structure due to the presence of intramolecular hydrogen bonds. Introducing formylphenyl in the form of ureido substitution can not only utilize the strong hydrogen bond action of the ureidopyrimidinone unit, but also further connect the structural units through the hydrogen bond action of the carboxyl group to form a two-dimensional extended structure. The two-dimensional extended structure is further combined through the π-π stacking interaction between the aromatic rings to form a crystalline polymer.

[0008] Furthermore, the crystalline polymer containing quadruple hydrogen bonds has a high crystallinity, and the X-ray powder diffraction pattern shows obvious diffraction peaks.

[0009] Furthermore, the crystalline polymer containing quadruple hydrogen bonds has high thermal stability, and thermogravimetric analysis shows that it can be stable up to 250°C.

[0010] Furthermore, the crystalline polymer containing quadruple hydrogen bonds has luminescent properties, and its maximum emission peak wavelength is 410 nm.

[0011] Furthermore, the crystalline polymer containing quadruple hydrogen bonds is in the form of needle-like or ribbon-like microcrystals and can still maintain its complete structure up to 250°C.

[0012] The second object of the present invention is to provide a preparation method of a crystalline polymer containing quadruple hydrogen bonds, including the following steps:

[0013] S1. Preparation of 3,5-bis(ethyl benzoyl)aniline: Mix 3,5-dibromoaniline and 4-ethoxycarbonylphenylboronic acid in a Schlenk flask, add tetrahydrofuran and aqueous sodium carbonate solution, then deoxygenate by bubbling nitrogen for at least 30 minutes. Then add tetrakis(triphenylphosphine)palladium, and continue to deoxygenate by bubbling nitrogen for at least 30 minutes. Heat to 80 °C and react for at least 72 hours. After the reaction is completed, separate the organic phase and dry it with anhydrous MgSO4. Concentrate the filtrate and perform silica gel column chromatography to obtain pale yellow solid 3,5-bis(ethyl benzoyl)aniline;

[0014] S2. Preparation of 2-amino-6-propyl-4[1H]pyrimidinone: Mix ethyl butyrylacetate and guanidine carbonate, add anhydrous ethanol, and heat to 70 °C under nitrogen protection and react for at least 8 hours. After the reaction is completed, after the first post-treatment, filter by suction to obtain white solid 2-amino-6-propyl-4[1H]pyrimidinone;

[0015] S3. Preparation of 2-(1-imidazolylcarbonylamino)-6-propyl-4[1H]pyrimidinone: Mix 2-amino-6-propyl-4[1H]pyrimidinone obtained in step S2 and N,N'-carbonyldiimidazole, add dimethyl sulfoxide, and heat to 60 °C under nitrogen protection and react for 4 hours. After the reaction is completed, after the second post-treatment, obtain white solid 2-(1-imidazolylcarbonylamino)-6-propyl-4[1H]pyrimidinone;

[0016] S4. Preparation of 1-(1,3-bis(4-ethyl benzoyl)phenyl)-3-(6-propyl-4[1H]pyrimidin-2-yl)urea: Mix 3,5-bis(ethyl benzoyl)aniline obtained in step S1 and 2-(1-imidazolylcarbonylamino)-6-propyl-4[1H]pyrimidinone obtained in step S3, add dry N,N'-dimethylformamide and a small amount of triethylamine, and react at 70 °C under nitrogen protection for at least 24 hours. After the reaction is completed, after the third post-treatment, obtain white solid 1-(1,3-bis(4-ethyl benzoyl)phenyl)-3-(6-propyl-4[1H]pyrimidin-2-yl)urea;

[0017] S5. Preparation of 1-(1,3-bis(4-benzoyl)phenyl)-3-(6-propyl-4[1H]pyrimidin-2-yl)urea: To 1-(1,3-bis(4-ethyl benzoyl)phenyl)-3-(6-propyl-4[1H]pyrimidin-2-yl)urea obtained in step S4, successively add tetrahydrofuran, methanol, deionized water and lithium hydroxide. After ultrasonic treatment, heat to 80 °C and react for at least 8 hours. After the reaction is completed, after the fourth post-treatment, obtain 1-(1,3-bis(4-benzoyl)phenyl)-3-(6-propyl-4[1H]pyrimidin-2-yl)urea;

[0018] S6. Preparation of Crystalline Polymer Containing Quadruple Hydrogen Bonds: The crystalline polymer is prepared by the method of heating for dissolution and cooling for crystallization. An appropriate amount of N,N'-dimethylformamide is added to 1-(1,3-bis(4-carboxyphenyl)phenyl)-3-(6-propyl-4[1H]pyrimidin-2-yl)urea obtained in step S5, and it is heated until completely dissolved. After natural cooling and standing for 24 h, white microcrystalline powder can be observed to precipitate at the bottom of the test tube, and the microcrystalline powder of the white crystalline polymer is obtained, which is the crystalline polymer containing quadruple hydrogen bonds.

[0019] Preferably, in step S2, the operation of the first post-treatment adopts at least one of silica gel column chromatography, rotary evaporation, vacuum filtration, acetone washing, and centrifugation.

[0020] Preferably, in step S3, the operation of the second post-treatment adopts at least one of silica gel column chromatography, rotary evaporation, vacuum filtration, acetone washing, and centrifugation.

[0021] Preferably, in step S4, the operation of the third post-treatment adopts at least one of silica gel column chromatography, rotary evaporation, vacuum filtration, acetone washing, and centrifugation.

[0022] Preferably, in step S5, the operation of the fourth post-treatment adopts at least one of silica gel column chromatography, rotary evaporation, vacuum filtration, acetone washing, and centrifugation.

[0023] Preferably, the total duration of nitrogen bubbling is not less than 1 hour before and after adding tetrakis(triphenylphosphine)palladium; in step S1, the molar ratio of 3,5-dibromoaniline, 4-ethoxycarbonylphenylboronic acid, and tetrakis(triphenylphosphine)palladium is 1:2.5:0.1.

[0024] Preferably, in step S2, the molar ratio of ethyl butyrylacetate and guanidine carbonate is 1:1.

[0025] Preferably, in step S3, the molar ratio of 2-amino-6-propyl-4[1H]pyrimidinone and N,N'-carbonyldiimidazole is 1:(6 - 8).

[0026] More preferably, in step S3, the molar ratio of 2-amino-6-propyl-4[1H]pyrimidinone and N,N'-carbonyldiimidazole is 1:6.

[0027] Preferably, in step S3, ultradry dimethyl sulfoxide (DMSO) (dimethyl sulfoxide with a water content of less than 50 ppm) is used.

[0028] Preferably, in step S3, the most suitable reaction time is 4 hours.

[0029] Preferably, in step S4, the volume ratio of N,N′-dimethylformamide (DMF) to triethylamine is 10:1; the molar ratio of 3,5-bis(ethyl benzoate)aniline to 2-(1-imidazolylcarbonylamino)-6-propyl-4[1H]pyrimidinone in the feed is 1:1.15.

[0030] Preferably, in step S5, the volume ratio of tetrahydrofuran (THF), methanol and deionized water is 3:1:1; in step S5, before the heating reaction, the ultrasonic time is not less than 1 hour.

[0031] Preferably, in step S6, the feed amount is (15 - 20) mg of 1-(1,3-bis(4-benzoic acid)phenyl)-3-(6-propyl-4[1H]pyrimidinone-2-yl)urea and 1 mL of N,N′-dimethylformamide.

[0032] More preferably, in step S6, the feed amount is 15 mg of 1-(1,3-bis(4-benzoic acid)phenyl)-3-(6-propyl-4[1H]pyrimidinone-2-yl)urea and 1 mL of N,N′-dimethylformamide.

[0033] Preferably, the heating and dissolving temperature is 120 °C, and the heating and dissolving time does not exceed 5 minutes.

[0034] Compared with the prior art, the present invention has the following characteristics:

[0035] 1) The method for preparing a crystalline polymer containing quadruple hydrogen bonds provided by the present invention results in a crystalline polymer containing quadruple hydrogen bonds with high crystallinity and thermal stability, and exhibits fluorescence properties.

[0036] 2) In the structure of the crystalline polymer containing quadruple hydrogen bonds provided by the present invention, there is an AADD-DDAA self-associating quadruple hydrogen bond, which plays a stabilizing role in the polymer structure and provides a reference for the synthesis of polymers with high crystallinity or hydrogen-bonded organic framework compounds.

[0037] 3) The method for preparing a crystalline polymer containing quadruple hydrogen bonds provided by the present invention has a simple route process, mild reaction conditions, high yield, and good repeatability.

[0038] 4) The method for preparing a crystalline polymer containing quadruple hydrogen bonds provided by the present invention uses the AADD-DDAA self-associating quadruple hydrogen bond for the construction of a crystalline polymer. Starting from this, it has important theoretical significance for exploring crystalline polymers based on multiple hydrogen bonds and related properties, and also lays a foundation for the application of crystalline polymers containing multiple hydrogen bonds. Description of the Drawings

[0039] Figure 1 Schematic diagram of the structural unit used in Examples 1 to 3 of the present invention;

[0040] Figure 2 Schematic diagram of the dimer formed by the structural units adopted in the first to third embodiments of the present invention through quadruple hydrogen bonding;

[0041] Figure 3 Schematic diagram of the structure of the crystalline polymer containing quadruple hydrogen bonds in the first to third embodiments of the present invention;

[0042] Figure 4 Flow chart of the synthesis method of the structural unit of the crystalline polymer containing quadruple hydrogen bonds in the first to third embodiments of the present invention;

[0043] Figure 5 X-ray powder diffraction pattern of the crystalline polymer containing quadruple hydrogen bonds in Embodiment 1 of the present invention;

[0044] Figure 6 Scanning electron microscope photograph of the crystalline polymer containing quadruple hydrogen bonds in Embodiment 1 of the present invention;

[0045] Figure 7 Thermogravimetric analysis spectrum of the crystalline polymer containing quadruple hydrogen bonds in Embodiment 1 of the present invention;

[0046] Figure 8 Fluorescence spectrum of the crystalline polymer containing quadruple hydrogen bonds in Embodiment 1 of the present invention. Detailed implementation manners

[0047] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the accompanying drawings and the following embodiments are only used to illustrate the present invention, rather than limiting the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made. These all belong to the protection scope of the present invention.

[0048] In the present technical solution, if the preparation means, materials, structures or composition ratios and other features are not clearly stated, they are all regarded as common technical features disclosed in the prior art.

[0049] The present technical solution provides a crystalline polymer containing quadruple hydrogen bonds and a preparation method thereof. Using 3,5-bis(ethyl benzoate) aniline and 2-amino-6-propyl-4[1H] pyrimidinone as raw materials, through condensation reaction and hydrolysis reaction, a dicarboxylic acid containing ureidopyrimidinone is obtained, and then through a crystallization method, a crystalline polymer is obtained. In the crystalline polymer, there is a strong quadruple hydrogen bonding between the ureidopyrimidinone units.

[0050] In the following examples, the raw materials used are all commercially available.

[0051] Example 1

[0052] In this embodiment, referring to Figure 1-4 , a crystalline polymer containing quadruple hydrogen bonds, 1-(1,3-bis(4-carboxyphenyl)phenyl)-3-(6-propyl-4[1H]pyrimidin-2-yl)urea, is provided. This structural motif can form dimers through the AADD-DDAA self-associative quadruple hydrogen bonds between the ureidopyrimidinone units, and the dimers further combine through hydrogen bonds between the carboxyl groups to form a crystalline polymer.

[0053] This crystalline polymer has a high crystallinity, and the X-ray powder diffraction pattern shows obvious diffraction peaks. Regular appearance can be observed in the scanning electron microscope photograph; this crystalline polymer has high thermal stability, and thermogravimetric analysis shows that it can be stable up to 250 °C; this crystalline polymer has luminescent properties, and its maximum emission peak wavelength is 410 nm, referring to Figure 5-8 .

[0054] In this embodiment, a preparation method of a crystalline polymer containing quadruple hydrogen bonds adopts the following synthesis steps:

[0055] a. Preparation of 3,5-bis(ethyl benzoate)aniline:

[0056] Mix 500 mg (2.0 mmol) of 3,5-dibromoaniline and 980 mg (5.0 mmol) of 4-ethoxycarbonylphenylboronic acid in a 200 mL Schlenk flask, add 100 mL of tetrahydrofuran and 50 mL of 2.0 mol·L -1 Na2CO3 solution, purge with N2 for 40 min to remove oxygen, add 230 mg (0.2 mmol) of tetrakis(triphenylphosphine)palladium, continue to purge with N2 for 40 min, most of the solid dissolves, and the mixture turns light yellow. Heat the mixture to 80 °C and react for 72 h. After stopping the reaction, let it stand and cool to room temperature. The solution layers, and the upper liquid is brownish-black. Separate the organic phase, extract the aqueous phase with ethyl acetate (3 × 50 mL), combine the extracts, dry with anhydrous MgSO4, and then remove the solvent under reduced pressure to obtain a black oily liquid. The crude product is separated and purified by silica gel column chromatography (ethyl acetate: petroleum ether = 1:5 as the eluent), and a pale yellow solid product is obtained after vacuum drying, with a yield of 45%; 1 1H NMR (400 MHz, DMSO-d6, ppm): δ 8.04 (d, J = 8.3 Hz, 4H), 7.82 (d, J = 8.3 Hz, 4H), 7.16 (s, 1H), 6.97 (d, J = 1.4 Hz, 2H), 5.48 (s, 1H), 4.34 (q, J = 7.1 Hz, 5H), 1.35 (t, J = 7.1 Hz, 7H); It can be known that 3,5-bis(ethyl benzoate)aniline is obtained;

[0057] b. Preparation of 2-amino-6-propyl-4[1H]pyrimidinone:

[0058] 0.95 mL (6.0 mmol) of ethyl butyrylacetate and 1.08 g (6.0 mmol) of guanidine carbonate were measured and placed in a 50 mL single-necked round-bottom flask. 20 mL of absolute ethanol was added, and the mixture was heated to 70 °C under nitrogen protection and reacted for 8 h. After removing the solvent by rotary evaporation, the product was cooled to 4 °C, filtered by suction, washed with cold acetone, the precipitate was collected, dried in vacuo to obtain a white solid with a yield of 68%; 1 1H NMR (600 MHz, DMSO-d6, ppm): δ 6.25 (s, 1H), 5.19 (s, 1H), 2.13 (t, J = 7.5 Hz, 2H), 1.53 (h, J = 7.4 Hz, 2H), 0.85 (t, J = 7.4 Hz, 3H); It can be known that 2-amino-6-propyl-4[1H]pyrimidinone was obtained;

[0059] c. Preparation of 2-(1-imidazolylcarbonylamino)-6-propyl-4[1H]pyrimidinone:

[0060] 500 mg (3.0 mmol) of 2-amino-6-propyl-4[1H]pyrimidinone prepared in the above step b and 2.63 g (18 mmol) of N,N'-carbonyldiimidazole were placed in a 10 mL single-necked round-bottom flask, 5 mL of ultra-dry DMSO was added, and the mixture was heated to 60 °C under nitrogen protection and stirred for 4 h. After the reaction was stopped, the mixture was brownish-red and turbid. After adding 200 mL of acetone, it was cooled overnight at 4 °C, filtered by suction, and the precipitate was washed with acetone to obtain a white solid with a yield of 80%; 1 1H NMR (400 MHz, DMSO-d6, ppm): δ 7.69 (s, 1H), 7.02 (d, J = 0.9 Hz, 2H), 6.40 (s, 2H), 5.33 (s, 1H), 2.21 - 2.11 (m, 2H), 1.51 (h, J = 7.4 Hz, 2H), 0.83 (t, J = 7.4 Hz, 3H); It can be known that 2-(1-imidazolylcarbonylamino)-6-propyl-4[1H]pyrimidinone was obtained;

[0061] d. Preparation of 1-(1,3-bis(4-ethyl benzoate)phenyl)-3-(6-propyl-4[1H]pyrimidinone-2-yl)urea:

[0062] Mix 100 mg (0.40 mmol) of 3,5-bis(ethyl benzoyl)aniline prepared in step a and 180 mg (0.46 mmol) of 2-(1-imidazolylcarbonylamino)-6-propyl-4[1H]pyrimidinone prepared in step c in a 25 mL single-necked round-bottom flask, add 5.00 mL of dry N,N′-dimethylformamide and 0.50 mL of triethylamine, and react at 70 °C for 24 h under nitrogen protection. After the reaction is completed, wash the precipitate with acetone (3 × 30 mL), and dry it under vacuum to obtain a white solid with a yield of 70%. The product has poor solubility in common solvents and a satisfactory NMR spectrum could not be obtained;

[0063] e. Preparation of 1-(1,3-bis(4-carboxyphenyl)phenyl)-3-(6-propyl-4[1H]pyrimidin-2-yl)urea:

[0064] Place 100 mg (0.18 mmol) of 1-(1,3-bis(4-ethyl benzoyl)phenyl)-3-(6-propyl-4[1H]pyrimidin-2-yl)urea prepared in step d in a 250 mL single-necked round-bottom flask, add 60 mL of tetrahydrofuran, and sonicate for 5 min. The system becomes milky and turbid. Add 20 mL of methanol, sonicate for 30 min, then add 20 mL of H2O and 221 mg (5.28 mmol) of LiOH·H2O, and continue to sonicate for 30 min. The solution becomes clear and transparent. Heat to 80 °C and react for 8 h. After stopping the reaction, cool to room temperature, filter through diatomaceous earth, add concentrated hydrochloric acid dropwise to the filtrate until pH = 1, and a white precipitate will precipitate immediately. Let it stand for sedimentation, centrifuge, and repeatedly wash the precipitate with distilled water until neutral, and dry it under vacuum to obtain a white product with a yield of 46%; 1 1H NMR (600 MHz, DMSO-d6, ppm): δ 12.89 (s, 1H), 10.09 (s, 1H), 8.06 (d, J = 8.2 Hz, 4H), 7.94 (d, J = 11.5 Hz, 3H), 7.89 (d, J = 8.2 Hz, 4H), 7.75 (s, 1H), 5.83 (s, 1H), 2.89 (s, 3H), 2.73 (s, 3H), 2.46 (s, 2H), 1.66 (d, J = 7.0 Hz, 2H), 0.94 (t, J = 7.3 Hz, 3H); It can be seen that 1-(1,3-bis(4-carboxyphenyl)phenyl)-3-(6-propyl-4[1H]pyrimidin-2-yl)urea is obtained;

[0065] f. Preparation of a crystalline polymer containing quadruple hydrogen bonds:

[0066] Weigh 15 mg of 1-(1,3-bis(4-benzoyl)phenyl)-3-(6-propyl-4[1H]pyrimidinone-2-yl)urea into a PYREX glass test tube, add 1.0 mL of N,N'-dimethylformamide, and ultrasonicate for 20 minutes to obtain a white turbid solution. Place it in a 120°C heating module to completely dissolve it. After 5 minutes, turn off the heating and cool it naturally. After standing at room temperature for 24 hours, white microcrystalline powder can be observed at the bottom of the test tube. Filter it and wash it with a small amount of acetone. The product is a crystalline polymer containing quadruple hydrogen bonds, with a yield of 65%. After the product is soaked in acetone for 2 days, it is vacuum dried for 24 hours, and the elemental analysis results are measured. The theoretical value [(C 28 H 26 N4O7·H2O) ∞ ]:C 63.39,H 4.94,N10.56; Found: C 63.00,H 5.05,N 10.29.

[0067] The obtained crystalline polymer containing quadruple hydrogen bonds was tested and analyzed (a certain amount of test samples were accumulated through multiple parallel experiments):

[0068] 1. Crystallinity of crystalline polymers:

[0069] About 30 mg of the crystalline polymer prepared in this example was used for X-ray powder diffraction test, with a scanning range of 3°<2θ<60° and a scanning step of 8° / min. Within the range of 3°<2θ<30°, a sharp diffraction peak of the sample can be observed, and the intensity is relatively high, indicating that the crystallinity of the sample is good. Figure 5 .

[0070] 2. Micromorphology of crystalline polymers:

[0071] After the crystalline polymer prepared in this example is dispersed, it is placed under a scanning electron microscope for observation, and a picture of the microscopic morphology of the sample can be obtained. The results show that the sample has a regular appearance, is needle-shaped or ribbon-shaped, and is micrometer-sized. Figure 6 .

[0072] 3. Thermal stability of crystalline polymers:

[0073] About 6 mg of the crystalline polymer prepared in this example was used for thermogravimetric analysis, with the scanning temperature range from room temperature to 600°C and the scanning rate of 10°C / min. The results showed that below 250°C, the sample lost less than 5% of its weight, which can be attributed to the small amount of solvent in the sample, indicating that the sample has high thermal stability. Figure 7 .

[0074] 4. Fluorescence property test of crystalline polymers:

[0075] Approximately 20 mg of the crystalline polymer prepared in this example was used for the test of solid-state fluorescence spectroscopy to obtain the excitation spectrum and emission spectrum. The results showed that the maximum excitation wavelength was 357 nm and the maximum emission wavelength was 410 nm. See Figure 8 .

[0076] In this example, a ureidopyrimidinone-based structural unit with quadruple strong hydrogen bonds was adopted. Strong dimers were formed through the quadruple hydrogen bond interaction of ureidopyrimidinone. There was a strong π-π stacking interaction between the aromatic rings of the groups. The structural stability of the crystalline polymer was achieved by the hydrogen bond interaction between carboxyl groups, and certain fluorescence characteristics were exhibited, thus showing broad application prospects for such polymers.

[0077] Example Two

[0078] This example is basically the same as Example One, with the special feature being:

[0079] In this example, in step c, 500 mg (3.0 mmol) of 2-amino-6-propyl-4[1H]pyrimidinone and 3.50 g (24 mmol) of N,N'-carbonyldiimidazole were weighed and placed in a 10 mL single-neck round-bottom flask. 5 mL of ultra-dry DMSO was added, and the mixture was heated to 60 °C under nitrogen protection and reacted for 4 h, then the reaction was stopped. After adding 200 mL of acetone, it was cooled overnight at 4 °C, filtered by suction, and the precipitate was washed with acetone. After drying, white solid 2-(1-imidazolylcarbonylamino)-6-propyl-4[1H]pyrimidinone was obtained, with a yield of 65%.

[0080] Example Three

[0081] This example is basically the same as the previous examples, with the special feature being:

[0082] In this example, in step f, 20 mg of 1-(1,3-bis(4-benzoic acid phenyl)-3-(6-propyl-4[1H]pyrimidinone-2-yl)urea was weighed and placed in a PYREX glass test tube. 1 mL of N,N'-dimethylformamide was added, and after ultrasonic treatment for 20 min, a white turbid solution was obtained. It was placed in a 120 °C heating module to completely dissolve it. After 5 min, the heating was turned off and it was allowed to cool naturally. After waiting for 24 h, white microcrystalline powder could be observed to precipitate at the bottom of the test tube. It was filtered by suction, and the product was washed with a small amount of acetone, with a yield of 60%.

[0083] The above description of the embodiments is provided to enable those of ordinary skill in the art to understand and use the invention. Obviously, those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A crystalline polymer containing quadruple hydrogen bonds, and the structural unit of the crystalline polymer containing quadruple hydrogen bonds is 1-(1,3-bis(4-benzoic acid phenyl)-phenyl)-3-(6-propyl-4-[1 H pyrimidinone-2-yl)urea; The 1-(1,3-bis(4-carboxyphenyl)phenyl)-3-(6-propyl-4-[1 H pyrimidin-2-yl)urea contains a ureidopyrimidinone unit and a carboxyl group; Dimer is formed by AADD-DDAA self-associating quadruple hydrogen bonding between ureidopyrimidinone units, and the dimer further forms a two-dimensional extended structure through hydrogen bonding between carboxyl groups. The two-dimensional extended structure then combines through π-π stacking between aromatic rings to form the crystalline polymer containing quadruple hydrogen bonds.

2. The crystalline polymer containing quadruple hydrogen bonds according to claim 1, characterized in that, The maximum emission peak wavelength of the crystalline polymer containing quadruple hydrogen bonds is 410 nm.

3. A method for preparing a crystalline polymer containing quadruple hydrogen bonds as described in any one of claims 1 or 2, characterized in that, The preparation method includes the following steps: S1. Preparation of 3,5-bis(ethyl benzoylformate)aniline: Mix 3,5-dibromoaniline and 4-ethoxycarbonylphenylboronic acid, add tetrahydrofuran and aqueous sodium carbonate solution, then bubble with nitrogen to remove oxygen for at least 30 minutes. Then add tetrakis(triphenylphosphine)palladium, and continue to bubble with nitrogen to remove oxygen for at least 30 minutes. Heat to 80 °C and react for at least 72 hours. After the reaction is completed, separate the organic phase and dry it with anhydrous MgSO4. Concentrate the filtrate and perform silica gel column chromatography separation to obtain 3,5-bis(ethyl benzoylformate)aniline. S2. Preparation of 2-amino-6-propyl-4[1 H pyrimidinone: Ethyl butyrylacetate and guanidine carbonate were mixed, anhydrous ethanol was added, and the mixture was heated to 70 °C under nitrogen protection for at least 8 h. After the reaction was completed, through the first post-treatment, white solid 2-amino-6-propyl-4[1 H pyrimidinone was obtained by suction filtration; S3. Preparation of 2-(1-imidazolylcarbonylamino)-6-propyl-4[1 H pyrimidinone: Mix the 2-amino-6-propyl-4[1 H pyrimidinone obtained in step S2 with N,N'-carbonyldiimidazole, add dimethyl sulfoxide, and heat to 60 °C under nitrogen protection for 4 hours. After the reaction is completed, through the second post-treatment, 2-(1-imidazolylcarbonylamino)-6-propyl-4[1 H pyrimidinone is obtained; S4. Preparation of 1-(1,3-bis(4-ethyl benzoyl) phenyl)-3-(6-propyl-4[1 H pyrimidinone-2-yl) urea: Mix the 3,5-bis(ethyl benzoyl) aniline obtained in step S1 and the 2-(1-imidazolyl carbonyl amino)-6-propyl-4[1 H pyrimidinone obtained in step S3, add N,N'-dimethylformamide and triethylamine, react at 70 °C for at least 24 hours under nitrogen protection. After the reaction is completed, through the third post-treatment, 1-(1,3-bis(4-ethyl benzoyl) phenyl)-3-(6-propyl-4[1 H pyrimidinone-2-yl) urea is obtained; S5. Preparation of 1-(1,3-bis(4-carboxyphenyl)phenyl)-3-(6-propyl-4[1 H pyrimidin-2-yl)urea: To 1-(1,3-bis(4-ethoxycarbonylphenyl)phenyl)-3-(6-propyl-4[1 H pyrimidin-2-yl)urea obtained in step S4, tetrahydrofuran, methanol, deionized water and lithium hydroxide were added successively. After ultrasonic treatment, the mixture was heated to 80 °C and reacted for at least 8 hours. After the reaction was completed, after the fourth post-treatment, 1-(1,3-bis(4-carboxyphenyl)phenyl)-3-(6-propyl-4[1 H pyrimidin-2-yl)urea was obtained; S6. Preparation of crystalline polymer containing quadruple hydrogen bonds: The crystalline polymer is prepared by the method of heating, dissolving, cooling and crystallizing. N, N'-dimethylformamide is added to 1-(1,3-bis(4-carboxyphenyl)phenyl)-3-(6-propyl-4-[1 H pyrimidin-2-yl)urea obtained in step S5, and heated to dissolve all of 1-(1,3-bis(4-carboxyphenyl)phenyl)-3-(6-propyl-4-[1 H pyrimidin-2-yl)urea. After natural cooling and standing for 24 h, white microcrystalline powder is precipitated to obtain the microcrystalline powder of white crystalline polymer, which is the crystalline polymer containing quadruple hydrogen bonds.

4. The preparation method of a crystalline polymer containing quadruple hydrogen bonds according to claim 3, characterized in that, In step S2, the operation of the first post-treatment adopts at least one of silica gel column chromatography, rotary evaporation, vacuum filtration, acetone washing and centrifugation. In step S3, the operation of the second post-treatment adopts at least one of silica gel column chromatography, rotary evaporation, vacuum filtration, acetone washing and centrifugation. In step S4, the operation of the third post-treatment adopts at least one of silica gel column chromatography, rotary evaporation, vacuum filtration, acetone washing and centrifugation. In step S5, the operation of the fourth post-treatment adopts at least one of silica gel column chromatography, rotary evaporation, vacuum filtration, acetone washing and centrifugation.

5. The preparation method of a crystalline polymer containing quadruple hydrogen bonds according to claim 3, characterized in that, In step S1, the total duration of nitrogen bubbling before and after adding tetrakis(triphenylphosphine)palladium is not less than 1 hour. In step S1, the molar ratio of 3,5-dibromoaniline, 4-ethoxycarbonylphenylboronic acid and tetrakis(triphenylphosphine)palladium is 1:2.5:0.

1.

6. The preparation method of a crystalline polymer containing quadruple hydrogen bonds according to claim 3, wherein, In step S2, the molar ratio of ethyl butyrylacetate and guanidine carbonate is 1:

1.

7. The preparation method of a crystalline polymer containing quadruple hydrogen bonds according to claim 3, characterized in that, In step S3, the molar ratio of the feed of 2-amino-6-propyl-4[1 H pyrimidinone and N,N'-carbonyldiimidazole is 1:(6-8).

8. The preparation method of a crystalline polymer containing quadruple hydrogen bonds according to claim 3, characterized in that, In step S4, the volume ratio of N,N′-dimethylformamide and triethylamine is 10:

1. The molar ratio of the input of 3,5-bis(ethyl benzoyl)aniline and 2-(1-imidazolylcarbonylamino)-6-propyl-4[1 H pyrimidinone is 1:1.

15.

9. The preparation method of a crystalline polymer containing quadruple hydrogen bonds according to claim 3, characterized in that, In step S5, the volume ratio of tetrahydrofuran, methanol and deionized water is 3:1:

1. In step S5, before heating the reaction, the ultrasonic time is not less than 1 hour.

10. The preparation method of a crystalline polymer containing quadruple hydrogen bonds according to claim 3, characterized in that, In step S6, the feeding ratio of 1-(1,3-bis(4-carboxyphenyl)phenyl)-3-(6-propyl-4-[1 H pyrimidin-2-yl)urea to N,N′-dimethylformamide is (15 - 20 mg) : 1 mL; The heating and dissolution temperature is 120 °C, and the heating and dissolution time does not exceed 5 minutes.

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