HOFs material with X-ray response as well as preparation method and application of HOFs material

Abstract

The invention discloses a HOFs material with X-ray response as well as a preparation method and application of the HOFs material. Comprising construction unit molecules, the construction unit molecules are connected through intermolecular acting force, and the intermolecular acting force comprises a hydrogen bond; the structural general formula of the building unit molecule is as follows: in the formula, R1, R2, R3, R4 and R5 are respectively and independently selected from hydrogen, R1, R2, R3, R4 and R5 are respectively and independently selected from hydrogen, alkoxy, halogenated alkyl, benzoyl or thiol group, and the number of halogenations in the halogenated alkyl is from monosubstitution to maximum number substitution. In the process of preparing the HOFs material by using the organic construction unit compound with the structure involved in the scheme, an AIE group and a hydrogen bond functional group are introduced, and the organic framework X-ray scintillator with AIE characteristics is successfully constructed; the novel material shows the X-ray fluorescence response characteristic in direct proportion to the radiation intensity under the irradiation of X-rays with different intensities.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic photoelectric functional materials, and in particular to a HOFs material with X-ray response and a preparation method and application thereof. BACKGROUND

[0002] X-ray imaging technology has been widely used in many fields such as medical diagnosis, industrial flaw detection and security detection due to its unique advantages. In this technology system, the scintillator, as the core component, plays a crucial role. It is responsible for converting high-energy X-rays into easily detectable ultraviolet-visible light, and is the basis for achieving high-quality imaging.

[0003] At present, scintillators are mainly divided into two categories: inorganic and organic. Inorganic scintillators have many significant advantages, such as high light yield, which can generate a large amount of light signal; good response linearity, which can ensure the accuracy and stability of imaging. However, it also has some problems that cannot be ignored. The high cost restricts its large-scale application due to economic factors; the complex preparation process requires high technical requirements, which increases the difficulty and cost of production; the brittle texture is easy to damage during transportation, installation and use, which together restricts its further widespread application in the imaging field.

[0004] In contrast, organic scintillators exhibit unique advantages. It has good flexibility, which can adapt to different shapes and curved application scenarios; strong molecular designability, researchers can flexibly design and adjust the molecular structure according to specific needs; short fluorescence lifetime, which is beneficial to realize fast imaging and improve imaging efficiency. However, organic scintillators also face three major challenges in further development. First, there is an aggregation-caused quenching (ACQ) phenomenon, when the molecules are in an aggregated state, the luminescence efficiency will decrease sharply, which leads to a decrease in light yield in the solid state, and the imaging resolution also decreases. Second, the atomic number of the elements composing the organic scintillator is relatively low, and the absorption capacity of X-rays is weak, which leads to low sensitivity and poor detection limit in the imaging process, making it difficult to meet the needs of some high-precision detection. Third, the exciton utilization rate is low, and a large number of excitons cannot be effectively converted into light signals, which seriously restricts the improvement of luminescence efficiency. Therefore, in order to promote the development of organic scintillators, it is urgent to develop high-performance organic scintillators that can overcome the above problems and explore new material design strategies.

[0005] The emergence of AIE (aggregation-induced emission) materials brings new hope and effective path to solve the ACQ problem of traditional organic scintillators. Through careful and reasonable molecular structure design, the material is endowed with AIE characteristics. When the molecules are in an aggregated state, not only does the light-emitting quenching phenomenon not appear, but also the light-emitting efficiency can be significantly improved, thereby significantly improving the light yield and imaging resolution in the aggregated state. At present, AIE-type scintillators mainly include several categories such as traditional fluorescent type, TADF type (Thermally Activated Delayed Fluorescence), organic-inorganic hybrid type, metal cluster type and MOF type. For these different types of AIE-type scintillators, the performance optimization mainly depends on three strategies. One is to make full use of the AIE effect to inhibit the ACQ phenomenon and ensure that the light-emitting efficiency is still high in the aggregated state; the second is to construct a TADF structure to improve the utilization rate of excitons through special electronic structure, so that more excitons can be converted into light signals; the third is to introduce heavy atoms or metal components to enhance the X-ray absorption capacity of the material, thereby improving the imaging sensitivity and reducing the detection limit.

[0006] However, although certain progress has been made in the study of AIE-type scintillators, there are few reports on precise regulation of crystal structure to improve the performance of scintillators. As an important influencing factor of material performance, precise regulation of crystal structure is expected to open up new ways to further improve the performance of scintillators, which has become an important direction and problem to be solved in the current field of research. As a new type of porous crystalline material assembled by organic units through hydrogen bonds, HOFs (Hydrogen-bonded Organic Frameworks) has the characteristics of easy repair and framework regulation due to the weak interaction of hydrogen bonds. The performance response can be changed by regulating the framework, which shows great development potential in specific application scenarios of scintillators.

[0007] Therefore, if some AIE scintillators can be prepared into HOFs materials, it will have good application prospects. SUMMARY

[0008] The present application aims to at least solve one of the problems in the prior art. To this end, the present application proposes a compound which can be used to prepare a HOFs material.

[0009] The present application also proposes a HOFs material.

[0010] The present application also proposes the use of the above-mentioned compound in a HOFs material having an X-ray response.

[0011] According to one aspect of the present application, a compound is proposed, the structure of which is as follows:

[0012] wherein R1, R2, R3, R4 and R5 are independently selected from hydrogen, alkoxy, haloalkyl, benzoyl or thiol group, R1, R2, R3, R4 and R5 are not hydrogen at the same time and the number of methoxy groups in R1, R2, R3, R4 and R5 is 0 or 2-5, and the number of halogen in haloalkyl is mono-substituted to the maximum number of substitutions.

[0013] According to some embodiments of the present application, the alkoxy is C1-C6 alkoxy; and / or, the haloalkyl is C1-C6 haloalkyl.

[0014] According to some embodiments of the present application, R1, R2, R4 and R5 are hydrogen, and R3 is haloalkyl.

[0015] According to some embodiments of the present application, two of R2, R3 and R4 are alkoxy, and the other is hydrogen; R1 and R5 are hydrogen.

[0016] According to some embodiments of the present application, the halogen in haloalkyl is at least one of fluorine, chlorine, bromine or iodine.

[0017] According to some embodiments of the present application, the compound has a structure represented by one of the following formulas: .

[0018] According to another aspect of the present application, there is provided a method for preparing the compound as described above, comprising the following steps: Suzuki coupling reaction of tetra(4-bromophenyl)ethylene with phenylboronic acid having a corresponding functional group, to obtain the compound.

[0019] According to some embodiments of the present application, the reaction is carried out in the presence of a solvent, which is a mixture of toluene and ethanol or tetrahydrofuran.

[0020] According to some embodiments of the present application, the volume ratio of toluene to ethanol in the mixture of toluene and ethanol is 8.5-9.5:1.

[0021] According to some embodiments of the present application, the reaction temperature is 80-120℃, and the reaction time is 24-72 hours.

[0022] According to some embodiments of the present application, the reaction is carried out in a mixture of toluene and ethanol as the solvent, the reaction temperature is 100-120℃, and the reaction time is 24-48 hours.

[0023] According to some embodiments of the present application, the reaction is carried out in tetrahydrofuran as the solvent, the reaction temperature is 80-90℃, and the reaction time is 24-72 hours.

[0024] According to still another aspect of the present application, there is provided a hydrogen-bonded organic framework (HOFs) comprising building unit molecules connected through intermolecular forces, the intermolecular forces comprising hydrogen bonds. The building unit molecules have the following general structure:

[0025] wherein R1, R2, R3, R4and R5are each independently selected from hydrogen, alkoxy, haloalkyl, benzoyl or thiol, the haloalkyl having from one to the maximum number of halogen substitutions.

[0026] According to some embodiments of the present application, the alkoxy is C1-C6alkoxy; and / or, the haloalkyl is C1-C6haloalkyl.

[0027] According to some embodiments of the present application, the halogen in the haloalkyl is at least one of fluorine, chlorine, bromine or iodine.

[0028] According to some embodiments of the present application, R1, R2, R3, R4and R5are not simultaneously hydrogen.

[0029] According to some embodiments of the present application, the hydrogen bond comprises at least one of C-H…π, C-H…F, C-H…O, C-H…Cl, C-H…Br, C-H…I, S-H…S, C-H…S.

[0030] According to some embodiments of the present application, the hydrogen bond comprises at least one of C-H…π, C-H…F, C-H…O, C-H…Cl, C-H…Br, C-H…I.

[0031] According to some embodiments of the present application, the intermolecular forces further comprise at least one of electrostatic interaction, van der Waals force.

[0032] According to some embodiments of the present application, the hydrogen-bonded organic framework has a porous structure in the projection in at least one direction, the pores in the porous structure being regularly arranged.

[0033] According to some embodiments of the present application, the pores have a size of 100-500 Å 3 and a porosity of 5-20%. The pore size and porosity vary with the R group.

[0034] According to some embodiments of the present application, the hydrogen-bonded organic framework further comprises solvent molecules.

[0035] According to some embodiments of the present application, the structural formula of the building unit molecule is shown in one of the following formulas: .

[0036] According to another aspect of the present application, a preparation method of the above material is also provided, comprising the following steps: Suzuki coupling reaction of tetra(4-bromophenyl)ethylene with phenylboronic acid with corresponding functional groups to synthesize the building unit molecule, and crystallization of the building unit molecule by solvent diffusion method or solvent evaporation method to obtain the hydrogen-bonded organic framework material.

[0037] According to some embodiments of the present application, the preparation method comprises the following steps: dissolving the building unit molecule with a good solvent A and adding a poor solvent B to culture the crystal by liquid-liquid diffusion method; or dissolving the building unit molecule with the solvent A and then culturing the crystal by gas-phase diffusion method, to obtain the hydrogen-bonded organic framework material; wherein the solvent A comprises at least one of dichloromethane, trichloromethane, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, toluene, acetone, 1,4-dioxane or ethyl acetate; and the solvent B comprises at least one of methanol, ethanol, alkane, water, acetonitrile or dimethyl sulfoxide.

[0038] According to some embodiments of the present application, the volume of the poor solvent B is 0.2-1 times of the volume of the good solvent A.

[0039] According to some embodiments of the present application, the good solvent A is at least one of dichloromethane, tetrahydrofuran or chloroform, and the poor solvent B is at least one of methanol or n-hexane.

[0040] According to some embodiments of the present application, the process of culturing the crystal comprises a sealing and standing operation. The building unit molecule is dissolved with a good solvent A, and a poor solvent B is added dropwise to the building unit molecule for sealing and standing to culture the crystal. Or the building unit molecule is dissolved with a good solvent A, and the crystal is directly cultured by sealing and standing.

[0041] According to another aspect of the present application, the above material is also provided for use in X-ray detection or imaging.

[0042] Compared with the prior art, the present application has at least the following beneficial effects: The HOFs material in the scheme of the present application can realize self-assembly between the organic building unit compounds by means of intermolecular forces, and further form a hydrogen bond-organic framework material with X-ray response characteristics; in the process of preparing the HOFs material by using the organic building unit compounds of the structure involved in the scheme of the present application, an aggregation-induced emission (AIE) group and a hydrogen bond functional group are introduced, and an organic framework X-ray scintillator with AIE characteristics is successfully constructed; the novel material exhibits X-ray fluorescence response characteristics proportional to the radiation intensity under X-ray irradiation of different intensities. Moreover, the novel material has the advantages of short decay time and fast response speed, and has great application potential in the field of X-ray detection and imaging, and opens up a new way for constructing high-light-yield and high-resolution X-ray organic scintillators.

[0043] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 It is the nuclear magnetic hydrogen spectrum of the building unit molecule prepared in Example 1 of the present application.

[0045] Figure 2 It is the nuclear magnetic hydrogen spectrum of the building unit molecule prepared in Example 2 of the present application.

[0046] Figure 3 It is the nuclear magnetic hydrogen spectrum of the building unit molecule prepared in Example 3 of the present application.

[0047] Figure 4 It is the hydrogen bond organic framework schematic diagram and intermolecular interaction of the target crystal (a) along the a-axis when viewed from above in Example 1 of the present application; (b) interlayer interaction observed along the c-axis (c) hole schematic diagram along the a-axis. In the figure, the atom color: gray: C; white: H; green: F.

[0048] Figure 5 It is the hydrogen bond organic framework schematic diagram and intermolecular interaction of the target crystal (a) obtained by culturing in dichloromethane / methanol in Example 2 of the present application (solvent retained); (b) interlayer interaction observed along the c-axis (solvent retained); (c) hydrogen bond organic framework hole schematic diagram (solvent deleted). In the figure, the atom color: gray: C; white: H; red: O; green: Cl.

[0049] Figure 6 It is the hydrogen bond organic framework schematic diagram and intermolecular interaction of the target crystal (a) obtained by culturing in Example 3 of the present application (solvent retained); (b) hydrogen bond organic framework hole schematic diagram. In the figure, the atom color: gray: C; white: H; red: O; green: Cl.

[0050] Figure 7 are the fluorescence emission spectra and lifetime spectra of the crystalline powders obtained by recrystallization of the inventive examples 1, 2 and 3.

[0051] Figure 8 are the radioluminescence spectra (X-ray power voltage is 20 KV) of the crystalline powders obtained by recrystallization of the inventive examples 1, 2 and 3. DETAILED DESCRIPTION

[0052] The concept and the technical effects of the present application will be described clearly and completely in combination with the examples. It is obvious that the described examples are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative effort are within the scope of the present application. The test methods used in the examples are conventional methods unless otherwise specified. The materials and reagents used are commercially available unless otherwise specified. The same parameters are used in the same way in each example unless otherwise specified. The examples described below are exemplary and are used to explain the present application, but cannot be understood as limiting the present application.

[0053] In the description of the present application, the description of the terms "some embodiments" and the like means that the specific features, structures, materials or characteristics described in combination with the embodiments or examples are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0054] In the description of the present application, if there is a description of first, second, etc., it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of indicated technical features.

[0055] Unless otherwise specified, "room temperature" in the present application means 25℃±5℃.

[0056] Unless otherwise specified, "about" in the present application means that the allowable error is within ±2%.

[0057] Hydrogen-bonded organic frameworks (HOFs) are a new class of porous crystalline materials, which are self-assembled from building block molecules through hydrogen bonds. They possess many excellent properties, such as flexible structure, mild synthesis condition, easy repair, low toxicity and good biocompatibility. Especially, HOFs have a unique "self-adaptive" property, which can dynamically adjust their pore structure and luminescent sites under external stimuli. This property provides a new possibility for optimizing the scintillation performance of materials from the perspective of crystal engineering.

[0058] Example 1 The present example provides a HOFs material, which is self-assembled from building block molecules through intermolecular forces. The structure of the building block molecule is as follows: .

[0059] The preparation process of the above material is as follows: 1) Preparation of building block molecules: The building block molecules are prepared according to the following route: .

[0060] In a 250 mL three-necked flask, add tetra (4-bromophenyl) ethylene (1.00 g, 1.54 mmol), add 90 mL of a methanol solution and 10 mL of anhydrous ethanol, and perform oxygen removal by bubbling under an argon atmosphere, then add 2 M K2CO3 aqueous solution (1.17 g, 8.49 mmol). After stirring the mixture under an argon atmosphere for 30 min, add an appropriate amount of Pd(PPh3)4, bubble for 15 min, then add 4-trifluoromethyl phenylboronic acid (1.32 g, 6.94 mmol), and react at 120 ℃ for 24 hours. After the reaction is completed, cool to room temperature, and spin dry in a rotary evaporator. Purify the crude product by silica gel column chromatography, elute with DCM / PE (v / v = 1:9), then recrystallize with DCM / MeOH, and the yield is 54% (g). The nuclear magnetic hydrogen spectrum is as shown in Figure 1 . 1 HNMR (500MHz, Chloroform-d) δ 7.66 (s, 16H), 7.43 (d, J = 8.3 Hz, 8H), 7.22 (d, J =8.3 Hz, 8H). 2) Cultivation of hydrogen-bonded organic framework crystals: Add 0.02 g of the molecular unit synthesized in step 1) to a sample bottle, dissolve with 30 ml of dichloromethane, slowly add 30 ml of n-hexane, seal and stand for one week, cultivate the target crystals, and obtain the hydrogen-bonded organic framework product.

[0061] Example 2 The present example provides a kind of HOFs material, which is connected by self-assembly of building unit molecules by intermolecular forces.The structure formula of its building unit molecule is as follows: .

[0062] The preparation process of the above material is as follows: 1) preparation of building unit molecule: The building unit molecule is prepared according to the following route: .

[0063] The specific synthesis operation can refer to the step 1) of example 1, except that 4-trifluoromethylphenyl boronic acid is replaced by p-methoxyphenyl boronic acid to synthesize tetra-(4-methoxyphenyl) tetraphenyl ethylene, and the yield is 45%.The nuclear magnetic hydrogen spectrum is as shown in Figure 2 . 1 HNMR (500 MHz, Chloroform- d ) δ 7.53 (d, J = 7.7 Hz, 8H), 7.37 (d, J = 7.9 Hz,8H), 7.17 (s, 8H), 6.98 – 6.93 (m, 8H), 3.86 (s, 12H). 2) culture of hydrogen bond organic framework crystal: 0.02g of the molecular unit synthesized in step 1) is added in a sample bottle, dissolved with 30ml of dichloromethane, and then 15ml of methanol is slowly added and dropped, sealed and placed for a week, to culture the target crystal, and obtain the hydrogen bond organic framework product.

[0064] Example 3 The present example provides a kind of HOFs material, which is connected by self-assembly of building unit molecules by intermolecular forces.The structure formula of its building unit molecule is as follows: .

[0065] The preparation process of the above material is as follows: 1) preparation of building unit molecule: The building unit molecule is prepared according to the following route: .

[0066] The specific synthesis operation can refer to the step 1) of example 1, except that 4-trifluoromethylphenyl boronic acid is replaced by p-methoxyphenyl boronic acid to synthesize tetra-(4-methoxyphenyl) tetraphenyl ethylene, and the yield is 45%.The nuclear magnetic hydrogen spectrum is as shown in Figure 3 .

[0067] 2) Culturing hydrogen-bonded organic framework crystals: In a sample bottle, 0.02 g of the molecular unit synthesized in step 1) was dissolved in 30 ml of dichloromethane, and 15 ml of methanol was slowly added dropwise. After sealing and standing for a week, the target crystal was cultured, and a hydrogen-bonded organic framework product was obtained.

[0068] The target crystals obtained in Examples 1, 2 and 3 were subjected to X-ray diffraction test to obtain the structure data of the crystals, and the structure schematic diagram was drawn by data analysis as shown in Figures 4-6 . Among them, the target crystal cultured by dichloromethane / n-hexane in Example 1 can be observed to have obvious porous holes when viewed along the a-axis, and the multiple holes are regularly arranged, with a void volume of 349.74 Å 3 and a porosity of 14.8%. The target crystal obtained by dichloromethane / methanol culture in Example 2 has solvent molecules in the framework, two dichloromethane molecules in one hole, and obvious regularly arranged porous holes can be observed when viewed along the a-axis, with a void volume of 151.96 Å 3 and a porosity of 7.2%. The target crystal obtained by dichloromethane / methanol culture in Example 3 can be observed to have obvious porous holes when viewed along the b-axis, and each hole has one dichloromethane molecule, and the multiple holes are regularly arranged, with a void volume of 439.37 Å 3 and a porosity of 17.0%. In summary, the example monomer molecules can obtain corresponding hydrogen-bonded organic framework materials by solvent culture method.

[0069] The products obtained in Example 1 (TPE-4PF) and Example 2 (TPE-4PO) were recrystallized in dichloromethane, respectively, to obtain the crystalline powder of the target compound, and the product obtained in Example 3 (TPE-4P8O) was recrystallized in a mixed solvent of dichloromethane and methanol to obtain the crystalline powder of the target compound. Subsequently, the obtained materials were tested for steady-state spectrum, transient spectrum and X-ray response performance. Among them, the fixed voltage was 20 KV during the X-ray response test, the current was gradually increased, and the X-ray response of the crystalline state was tracked, and the results are shown in Figure 7 and Figure 8 . As can be seen from Figure 7 , the emission peaks of the steady-state spectra of Examples 1, 2 and 3 are 462 nm, 485 nm and 475 nm, respectively. The transient lifetimes are 2.33 ns, 1.99 ns and 1.87 ns, respectively, which are all fluorescent lifetimes. As can be seen from Figure 8 , the crystalline products of TPE-4PF, TPE-4PO and TPE-4P8O all have good X-ray response performance.

[0070] The above has made detailed description to the embodiment of the application, but the application is not limited to the above embodiment, and various changes can be made within the knowledge range possessed by the ordinary skilled in the art without departing from the purpose of the application.

Claims

1. A compound, characterized in that: The structural formula of the compound is as follows: In the formula, R1, R2, R3, R4 and R5 are independently selected from hydrogen, alkoxy, halogenated alkyl, benzoyl or thiol group, R1, R2, R3, R4 and R5 are not hydrogen at the same time, and the number of methoxy groups in R1, R2, R3, R4 and R5 is 0 or 2-5.

2. The method of claim 1, wherein: The method comprises the following steps:

3. A hydrogen-bonded organic framework material characterized by: The method comprises the following steps: The method comprises the following steps: The structural formula of the building unit molecule is as follows:

4. The hydrogen-bonded organic framework of claim 3, wherein: In the formula, R1, R2, R3, R4 and R5 are independently selected from hydrogen, alkoxy, halogenated alkyl, benzoyl or thiol group.

5. The hydrogen-bonded organic framework of claim 3, wherein: The hydrogen bond comprises at least one of C-H…π, C-H…F, C-H…O, S-H…S, C-H…S, C-H…Cl, C-H…Br and C-H…I; and / or, the intermolecular force further comprises at least one of electrostatic interaction and van der Waals force.

6. The hydrogen-bonded organic framework of claim 3, wherein: The projection of the hydrogen bond-organic framework material in at least one direction presents a porous structure, and the pores in the porous structure are regularly arranged. 。 7. The method of claim any one of claims 3 to 6, wherein: The structural formula of the building unit molecule is as shown in one of the following formulas: The method comprises the following steps:

8. The production method according to claim 7, characterized by: The method comprises the following steps: The method comprises the following steps:

9. The production method according to claim 8, characterized by: The method comprises the following steps: The method comprises the following steps: The good solvent A is selected from at least one of dichloromethane, tetrahydrofuran or chloroform, and the poor solvent B is selected from at least one of methanol or n-hexane; and / or, the process of culturing crystals comprises the operation of sealing and standing treatment.

10. The hydrogen bond-organic framework material according to any one of claims 3 to 6 is applied in X-ray detection or imaging.

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