Preparation method and application of a hybrid local-charge transfer excited state scintillator

Abstract

The present invention discloses a preparation method and application of a hybrid local-charge transfer excited state scintillator, belonging to the technical field of organic functional materials. The hybrid local-charge transfer excited state scintillator of the present invention overcomes the problems of weak X-ray absorption, low light yield and low X-ray imaging spatial resolution existing in the existing organic functional materials, and broadens the application of HLCT organic fluorescent materials in X-ray imaging. The hybrid local-charge transfer excited state scintillator of the present invention has a short synthesis step, high yield and novel structure, and for the first time, the interaction between the heavy atom and π electron in the molecule is regulated by the strategy of spatial heavy atoms, realizing the preparation of materials with HLCT luminescence mechanism.

Description

Technical Field

[0001] The present invention relates to the technical field of organic functional materials, and particularly to a preparation method and application of a hybrid local-charge transfer excited state scintillator. Background Art

[0002] X-ray imaging technology has important applications in many fields such as medical diagnosis, national defense industry, nuclear technology, and radiation safety detection. As the core device in the application of X-ray technology, a scintillator can convert high-energy X photons into low-energy visible light, thereby realizing X-ray detection and imaging. Currently, the vast majority of scintillator materials are inorganic materials synthesized by calcination under high-temperature conditions, which are not only expensive but also difficult to achieve large-area preparation on flexible substrates. As a new type of scintillator material, organic scintillators have great potential application value in the field of flexible electronics. However, traditional pure organic materials are mainly composed of light elements such as carbon, hydrogen, and nitrogen, and have weak absorption of X-rays. Therefore, 75% of the generated triplet excitons are not fully utilized, restricting the development of pure organic scintillator materials. Based on the above problems, researchers have used organic room-temperature phosphorescent materials and thermally activated delayed fluorescence to solve the problem of weak X-ray absorption. However, these materials also face the problem of long triplet exciton lifetimes and are not suitable for fast X-ray imaging. Thermally excited materials have shorter excited state lifetimes, but their light yields and X-ray imaging spatial resolutions are still relatively low. Therefore, it is particularly necessary to develop organic functional materials with high light yields, low detection lines, fast response times, and high-definition resolutions, and to provide a new strategy for the development of flexible X-ray detectors for non-destructive ray detection, medical imaging, and other fields. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method and application of a hybrid local-charge transfer excited state scintillator to solve the problems existing in the above-mentioned prior art.

[0004] The present invention obtains a novel and efficient organic scintillator (a hybrid local-charge transfer excited state scintillator) by modifying heavy atom groups on the basis of a hybrid local-charge transfer excited state (HLCT) material with benzothiadiazole as the acceptor and fluorene as the donor, and uses it for X-ray detection and imaging, overcoming the problems of weak X-ray absorption, low light yield, and low X-ray imaging spatial resolution existing in existing organic functional materials, and broadening the application of HLCT organic fluorescent materials in X-ray imaging.

[0005] To achieve the above purpose, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention: A hybrid local-charge transfer excited state scintillator, the structural formula of which is shown in Formula (1) or Formula (2):

[0007]

[0008] The compound of the formula (2) structure is formed by polymerization of m units of A structure and n units of B structure; the connection order of m units of A structure and n units of B structure is not fixed;

[0009] The A structure is:

[0010] The B structure is:

[0011] The m is an integer from 0 to 500, the n is an integer from 0 to 500, m and n are not both 0 at the same time, and m + n = 5 to 500;

[0012] Wherein, R1 and R2 each independently selected from any one of heavy atom-substituted C1-C12 alkyl, C1-C12 alkoxy, C6 aryl, C6-C12 aralkyl, C6-C12 aralkoxy;

[0013] R3 is selected from any one of oxygen, sulfur, selenium, tellurium, and nitrogen, phosphorus, arsenic containing substituents; the substituents are methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, 2,6-diisopropylphenyl, methoxy, ethoxy or propoxy which may or may not contain heavy atoms;

[0014] R4 is selected from any one of hydrogen, fluorine, chlorine, bromine, iodine, and oxygen, sulfur, selenium, tellurium, nitrogen, phosphorus, arsenic containing substituents; the substituents are methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, 2,6-diisopropylphenyl, methoxy, ethoxy or propoxy.

[0015] Further, the heavy atoms include any one of chlorine, bromine, iodine, sulfur, phosphorus, arsenic, tellurium, selenium, silicon, germanium;

[0016] The R1 is n-hexyl bromide or methyl mercapto; R2 is bromo(methoxymethoxy)methoxy methane bromide or (2-iodoethoxy)benzene; R3 is sulfur or 6-bromohexan-1-amine; R4 is methoxy or dimethylamine.

[0017] The second technical solution of the present invention: A preparation method of the above-mentioned hybrid local-charge transfer excited state scintillator, comprising the following steps:

[0018] The preparation method of the compound of the formula (1) structure includes: under a nitrogen atmosphere, mixing compound 1, a catalyst, a base and an organic solvent, then adding compound 2 and compound 3, heating and reacting after mixing evenly, and performing column chromatography separation after the reaction ends to obtain the hybrid local-charge transfer excited state scintillator;

[0019] The compound 1 is as follows:

[0020]

[0021] The compound 2 is as follows:

[0022]

[0023] The compound 3 is as follows:

[0024]

[0025] The preparation method of the compound of formula (2) includes: under a nitrogen atmosphere, mixing compound 1, a catalyst, a base and an organic solvent, then adding compound 4 and compound 5, heating and reacting after mixing evenly, and performing Soxhlet extraction after the reaction ends to obtain the hybrid local-charge transfer excited state scintillator;

[0026] The compound 4 is as follows:

[0027]

[0028] The compound 5 is as follows:

[0029]

[0030] It is described that R1 and R2 each independently selected from any one of heavy atom-substituted C1-C12 alkyl, C1-C12 alkoxy, C6 aryl, C6-C12 aralkyl, C6-C12 aralkoxy;

[0031] R3 is selected from any one of oxygen, sulfur, selenium, tellurium and nitrogen, phosphorus, arsenic containing substituents; the substituents are methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, 2,6-diisopropylphenyl, methoxy, ethoxy or propoxy with or without heavy atoms;

[0032] R4 is selected from any one of hydrogen, fluorine, chlorine, bromine, iodine and oxygen, sulfur, selenium, tellurium, nitrogen, phosphorus, arsenic containing substituents; the substituents are methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, 2,6-diisopropylphenyl, methoxy, ethoxy or propoxy;

[0033] The X is chlorine, bromine or iodine.

[0034] Further, the catalyst includes tetrakis(triphenylphosphine)palladium(0);

[0035] The base includes K2CO3;

[0036] The organic solvent includes toluene and methanol with a volume ratio of (2-5):(1-2).

[0037] Furthermore, the temperature of the heating reaction is 50 to 120 °C, and the time is 12 to 24 hours.

[0038] The third technical solution of the present invention: an application of the above-mentioned hybrid local-charge transfer excited state scintillator as a non-destructive ray detection material or a medical imaging material.

[0039] Furthermore, the medical imaging material includes an X-ray imaging material.

[0040] The fourth technical solution of the present invention: a flexible X-ray detector, and the preparation raw materials include the above-mentioned hybrid local-charge transfer excited state scintillator.

[0041] Organic scintillators are a class of organic materials that can emit light after absorbing high-energy particles or rays. There are mainly the following physical processes: when an organic scintillator material is excited by X-rays, high-energy X-ray photons have enough energy to ionize the molecules in the material, generating high-energy electrons. These high-energy electrons collide with other molecules in the material and transfer energy to more molecules through non-radiative transitions, generating secondary and tertiary electrons until the electron energy drops to about 2 to 4 times the band gap. In this excited state, localized excitons are formed between charges under radiative coupling. With the passage of time and the influence of internal physical and chemical processes of the molecules, these excited states will eventually recombine and emit photons.

[0042] The present invention greatly improves the performance of organic scintillators (hybrid local-charge transfer excited state scintillators), such as luminescence efficiency, Stokes shift, fluorescence lifetime, absorption cross-section, and broadening of the emission spectrum, by introducing a connection form with substituents having heavy atoms to the σ bond on the 9th carbon atom of fluorene. The light yield, detection line, response time, and resolution of the organic scintillator are also improved, so it has very important significance.

[0043] The present invention discloses the following technical effects:

[0044] (1) The hybrid local-charge transfer excited state scintillator of the present invention overcomes the problems of weak X-ray absorption, low light yield, and low X-ray imaging spatial resolution existing in existing organic functional materials, and broadens the application of HLCT organic fluorescent materials in X-ray imaging.

[0045] (2) The hybrid local-charge transfer excited state scintillator of the present invention has short synthesis steps, high yield, and novel structure, and for the first time regulates the interaction between heavy atoms and π electrons in the molecule through the strategy of spatial heavy atoms, realizing the preparation of materials with HLCT luminescence mechanism.

[0046] (3) The novel HLCT organic scintillator (hybrid local-charge transfer excited state scintillator) of the present invention has fast reverse intersystem crossing of high triplet-singlet energy levels (2.63×10 8 s -1 ), a large Stokes shift (>100 nm), a short triplet exciton lifetime (3.74 ns), and excellent fluorescence quantum yield (100%); and exhibits a very narrow X-ray emission spectrum with a full width at half maximum of 56 nm, a high light yield of approximately 42400 photons / MeV, and a low detection limit of 84.6 nGy s -1 . It can achieve a high X-ray imaging resolution of 40.5 lp mm -1 , overcome the deficiencies of existing organic scintillators, provide a feasible strategy for realizing a new type of stable and efficient organic scintillator, and have broad application prospects in the fields of X-ray detection and imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0048] Figure 1 Optical properties of organic substances A, B, C, and D prepared in Examples 1, 2, 3, and 4 of the present invention. Among them, a is the ultraviolet absorption and emission spectra of the films prepared from organic substances A, B, C, and D, b is the transient fluorescence lifetime decay curves of the films prepared from organic substances A, B, C, and D, c is the X-ray absorption curves of the films prepared from organic substances A, B, C, and D, and d is the X-ray excited spectra and light yields of the films prepared from organic substances A, B, C, and D and the reference CSI:T1.

[0049] Figure 2 Radioluminescence intensities of organic substances A, B, C, and D prepared in Examples 1, 2, 3, and 4 of the present invention under different X-ray dose rates. Among them, a is the film prepared from organic substance A prepared in Example 1, b is the film prepared from organic substance B prepared in Example 2, c is the film prepared from organic substance C prepared in Example 3, and d is the film prepared from organic substance D prepared in Example 4.

[0050] Figure 3The modulation transfer function (MTF) and spatial resolution of the X-ray inclined edge images of organic substances A, B, C, and D prepared in Examples 1, 2, 3, and 4 of the present invention. Among them, a is a thin film prepared from organic substance A prepared in Example 1, b is a thin film prepared from organic substance B prepared in Example 2, c is a thin film prepared from organic substance C prepared in Example 3, and d is a thin film prepared from organic substance D prepared in Example 4.

[0051] Figure 4 The bright-field and dark-field photos of the pen and pen core presented by organic substances A, B, C, and D prepared in Examples 1, 2, 3, and 4 of the present invention before and after X-ray exposure. Detailed implementation manners

[0052] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be regarded as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0053] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0054] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0055] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation manners of the present invention specification, which are obvious to those skilled in the art. Other implementation manners obtained from the present invention specification are obvious to those skilled in the art. The present invention specification and examples are only exemplary.

[0056] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0057] In the first aspect of the present invention, a hybrid local-charge transfer excited state scintillator is provided, and the structural formula is shown in Formula (1) or Formula (2):

[0058]

[0059]

[0060] The compound with the structure of Formula (2) is formed by polymerization of m units of Structure A and n units of Structure B;

[0061] The Structure A is:

[0062] The Structure B is:

[0063] The m is an integer from 0 to 500, the n is an integer from 0 to 500, m and n are not both 0 at the same time, and m + n = 5 to 500;

[0064] Wherein, R1 and R2 are each independently selected from any one of heavy atom-substituted C1-C12 alkyl, C1-C12 alkoxy, C6 aryl, C6-C12 aralkyl, and C6-C12 aralkoxy;

[0065] R3 is selected from any one of oxygen, sulfur, selenium, tellurium, and nitrogen, phosphorus, arsenic containing substituents; the substituent is methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, 2,6-diisopropylphenyl, methoxy, ethoxy or propoxy which contains or does not contain heavy atoms;

[0066] R4 is selected from any one of hydrogen, fluorine, chlorine, bromine, iodine, and oxygen, sulfur, selenium, tellurium, nitrogen, phosphorus, arsenic containing substituents; the substituent is methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, 2,6-diisopropylphenyl, methoxy, ethoxy or propoxy.

[0067] The heavy atoms in the present invention include any one of chlorine, bromine, iodine, sulfur, phosphorus, arsenic, tellurium, selenium, silicon, and germanium; R1 is n-hexyl bromide or methylthio; R2 is bromo(methoxymethoxy)methoxymethane bromide or (2-iodoethoxy)benzene; R3 is sulfur or 6-bromohexan-1-amine; R4 is methoxy or dimethylamine.

[0068] In the second aspect of the present invention, a preparation method of the above-mentioned hybrid local-charge transfer excited state scintillator is provided, including the following steps:

[0069] The preparation method of the compound of formula (1) includes: under a nitrogen atmosphere, mixing compound 1, a catalyst, a base and an organic solvent, then adding compound 2 and compound 3, heating and reacting after mixing evenly, and performing column chromatography separation after the reaction ends to obtain a hybrid local-charge transfer excited state scintillator;

[0070] Compound 1 is:

[0071]

[0072] Compound 2 is:

[0073]

[0074] Compound 3 is:

[0075]

[0076] The chemical reaction equation is as follows:

[0077]

[0078] The preparation method of the compound of formula (2) includes: under a nitrogen atmosphere, mixing compound 1, a catalyst, a base and an organic solvent, then adding compound 4 and compound 5, heating and reacting after mixing evenly, and performing Soxhlet extraction after the reaction ends to obtain a hybrid local-charge transfer excited state scintillator;

[0079] Compound 4 is:

[0080]

[0081] Compound 5 is:

[0082]

[0083] The chemical reaction equation is as follows:

[0084]

[0085] R1 and R2 each independently selected from any one of heavy atom-substituted C1-C12 alkyl, C1-C12 alkoxy, C6 aryl, C6-C12 aralkyl, C6-C12 aralkoxy; heavy atoms include any one of chlorine, bromine, iodine, sulfur, phosphorus, arsenic, tellurium, selenium, silicon, germanium;

[0086] R3 is selected from any one of oxygen, sulfur, selenium, tellurium and nitrogen, phosphorus, arsenic containing substituents; the substituents are methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, 2,6-diisopropylphenyl, methoxy, ethoxy or propoxy which may or may not contain heavy atoms;

[0087] R4 is selected from any one of hydrogen, fluorine, chlorine, bromine, iodine, and oxygen, sulfur, selenium, tellurium, nitrogen, phosphorus, and arsenic containing substituents; the substituents are methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, 2,6-diisopropylphenyl, methoxy, ethoxy, or propoxy;

[0088] X is chlorine, bromine, or iodine; m is an integer from 0 to 500, n is an integer from 0 to 500, m and n are not both 0, and m + n = 5 to 500.

[0089] The organic solvent used in the present invention includes toluene and methanol with a volume ratio of (2 to 5):(1 to 2).

[0090] The temperature of the heating reaction in the present invention is 50 to 120 °C, and the time is 12 to 24 hours.

[0091] In the third aspect of the present invention, there is provided an application of the above-mentioned hybrid local-charge transfer excited state scintillator as a non-destructive ray detection material or a medical imaging material.

[0092] In the fourth aspect of the present invention, there is provided a flexible X-ray detector, and the preparation raw materials include the above-mentioned hybrid local-charge transfer excited state scintillator.

[0093] Example 1

[0094] A preparation method of a hybrid local-charge transfer excited state scintillator (organic substance A):

[0095] Under a nitrogen atmosphere, 5,6-dimethoxy-4,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[c][1,2,5]thiadiazole (448 mg, 1 mmol), tetrakis(triphenylphosphine)palladium(0) (16 mg, 0.0144 mol), 2 M K2CO3 (6 mL), and toluene / methanol (5 mL / 1 mL) were added to a 50 mL three-necked flask and mixed evenly. Then, 9,9-bis(((bromomethoxy)methoxy)-2-iodo-9H-fluorene (693 mg, 1.1 mmol) and 2-bromo-9,9-bis(6-bromohexyl)-9H-fluorene (571 mg, 1.1 mmol) were added, and the mixture was heated to 80 °C and reacted for 12 hours. After cooling to room temperature, the reaction mixture was diluted with ether, and the organic phase was washed with brine. After drying with MgSO4, the solvent was removed. The obtained crude product was purified by silica gel column chromatography (using dichloromethane:petroleum ether, 1:5 to 10, v / v) to remove impurities, and recrystallized from dichloromethane / ethanol (1:10, v / v) to obtain a green product, which is the hybrid local-charge transfer excited state scintillator, and the product yield is 55%.

[0096] The chemical reaction equation is as follows:

[0097]

[0098] 1 1H NMR (500 MHz, CDCl3) δ 8.09 (s, 10H), 8.06 - 7.84 (m, 21H), 7.78 (s, 10H), 7.63 - 7.28 (m, 21H), 7.34 (s, 9H), 7.34 (s, 8H), 7.24 (s, 5H), 5.50 (s, 20H), 4.50 (s, 40H), 3.92 (s, 30H), 3.52 (s, 10H), 1.93 (s, 17H), 1.82 (s, 8H), 1.33 (s, 31H), 1.26 (s, 21H). 13 13C NMR (126 MHz, CDCl3) δ 158.03, 155.74, 150.34, 150.16, 142.39, 142.21, 138.53, 138.40, 137.29, 135.32, 133.48, 131.97, 130.37, 129.29, 128.78, 127.95, 125.80, 123.77, 123.48, 122.76, 120.78, 120.64, 120.52, 120.20, 119.03, 118.43, 110.48, 106.17, 94.21, 90.38, 60.70, 52.54, 40.16, 33.30, 31.58, 30.68, 29.54, 25.54. HRMS (m / z) calcd. for C 52 H 56 Br4N2O8S [M]+: 1184.0491; found: 1184.0477.

[0099] Example 2

[0100] A preparation method of a hybrid local - charge transfer excited state scintillator (organic compound B):

[0101] Under a nitrogen atmosphere, 2-(6-bromohexyl)-N5,N5,N6,N6-tetramethyl-4,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2H-benzo[d][1,2,3]triazole-5,6-diamine (620 mg, 1 mmol), tetrakis(triphenylphosphine)palladium(0) (16 mg, 0.0144 mol), 2 M K2CO3 (6 mL), and toluene / methanol (2 - 5 mL / 1 - 2 mL) were added to a 50 mL three-necked flask and mixed evenly. Then, 2,7-dibromo-9,9-bis(4-(2-iodoethoxy)phenyl)-9H-fluorene (898 mg, 1.1 mmol) and (2,7-dibromo-9H-fluoren-9,9-diyl)bis(methylsulfane) (458 mg, 1.1 mmol) were added, and the mixture was heated to 80 °C and reacted for 12 hours. After cooling to room temperature, the reaction mixture was diluted with diethyl ether, and the organic phase was washed with brine. After drying with MgSO4, the solvent was removed. The crude product was reprecipitated from ethanol, and n-hexane was used as the extraction solvent. Further purification was carried out by Soxhlet extraction to remove impurities, and a hybrid local-charge transfer excited state scintillator was obtained with a product yield of 52%.

[0102] The chemical reaction equation is as follows:

[0103]

[0104] Among them, m is an integer from 0 to 500, n is an integer from 0 to 500, and m + n = 5 to 500.

[0105] 1 H NMR (500 MHz, CDCl3) δ 8.10 - 7.73 (m) 7.30 - 7.20 (m), 6.83 - 6.78 (m), 4.50 - 4.06 (m), 3.68 - 3.50 (m), 2.98 - 2.13 (m), 1.94 - 1.32 (m). Mw: 12.3 kDa, PDI: 1.56.

[0106] Example 3

[0107] A preparation method of a hybrid local-charge transfer excited state scintillator (organic compound C):

[0108] Under a nitrogen atmosphere, 5,6-difluoro-4,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[c][1,2,5]selenadiazole (471 mg, 1 mmol), tetrakis(triphenylphosphine)palladium(0) (16 mg, 0.0144 mol), 2 M K2CO3 (6 mL), and toluene / methanol (5 mL / 1 mL) were added to a 50 mL three-necked flask and mixed evenly. Then, (2-bromo-9H-fluoren-9-ylidene)bis(4,1-phenylene))bis(trimethylgermane) (1388 mg, 2.2 mmol) was added, and the mixture was heated to 80 °C and reacted for 12 hours. After cooling to room temperature, the reaction mixture was diluted with diethyl ether, and the organic phase was washed with brine. After drying with MgSO4, the solvent was removed. The resulting crude product was purified by silica gel column chromatography (using dichloromethane:petroleum ether, 1:5 - 10, v / v) to remove impurities and recrystallized from dichloromethane / ethanol (1:10, v / v) to obtain a green product, which is a hybrid local-charge transfer excited state scintillator with a product yield of 82%.

[0109] The chemical reaction equation is as follows:

[0110]

[0111] 1 H NMR (500 MHz, CDCl3) δ 8.11 - 7.72 (m, 3H), 7.58 (s, 1H), 7.34 (d, J = 6.4 Hz, 5H), 7.24 (s, 1H), 7.20 (s, 1H), 7.16 (s, 4H), 1.33 (s, 18H). 13 C NMR (125 MHz, CDCl3) δ 163.84, 148.82, 147.21, 147.07, 138.34, 137.06, 134.67, 129.58, 126.88, 126.88, 124.79, 122.86, 119.49, 119.08, 116.63, 109.16, 67.21, 34.58, 31.36. HRMS (m / z) calcd. for C68H66F2Ge4N2Se [M]+: 1324.1206; found: 1324.1209.

[0112] Example 4

[0113] A preparation method of a hybrid local-charge transfer excited state scintillator (organic compound D): Under a nitrogen atmosphere, 2-isopropyl-4,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2H-benzo[d][1,3,2]diazaphosphole (430 mg, 1 mmol), tetrakis(triphenylphosphine)palladium(0) (16 mg, 0.0144 mol), 2 M K2CO3 (6 mL) and toluene / methanol (2 - 5 mL / 1 - 2 mL) were added to a 50 mL three-necked flask and mixed evenly. Then, ((2,7-dibromo-9H-fluorene-9,9-diyl)bis(4,1-phenylene)bis(propane-3,1-diyl))bis(dimethylarsine) (768 mg, 1 mmol) was added, and the mixture was heated to 80 °C and reacted for 12 hours. After cooling to room temperature, the reaction mixture was diluted with ether, and the organic phase was washed with brine. After drying with MgSO4, the solvent was removed. The crude product was reprecipitated from ethanol, and n-hexane was used as the extraction solvent. It was further purified by Soxhlet extraction to remove impurities, obtaining a hybrid local-charge transfer excited state scintillator with a product yield of 52%.

[0114] The chemical reaction equation is as follows:

[0115]

[0116] Among them, n is an integer from 5 to 500.

[0117] 1 H NMR (500 MHz, CDCl3) δ 8.14 - 7.70 (m) 7.34 - 7.21 (m), 6.82 - 6.75 (m), 4.55 - 4.01 (m), 3.66 - 3.52 (m), 2.96 - 2.11 (m), 1.99 - 1.37 (m). Mw: 14.2 kDa, PDI: 1.61.

[0118] Effect Example 1

[0119] The optical properties of organic compounds A, B, C, and D prepared in Examples 1, 2, 3, and 4 are shown in Figure 1 , Figure 1 where a is the ultraviolet absorption and emission spectra of the films (scintillator films) prepared from organic compounds A, B, C, and D, b is the transient fluorescence lifetime decay curves of the films prepared from organic compounds A, B, C, and D, c is the X-ray absorption curves of the films prepared from organic compounds A, B, C, and D, and d is the X-ray excitation spectra and light yields of the films prepared from organic compounds A, B, C, and D and the reference CSI:T1.

[0120] From Figure 1As can be seen from Figure a, the main absorption peaks of the ultraviolet-visible absorption spectra of organic compounds A, B, C, and D are around 420 nm; the emission peaks of the fluorescence spectra of organic compounds A, B, C, and D are 508 - 539 nm respectively. This indicates that these organic compounds all have a large Stokes shift and thus have very small self-absorption.

[0121] From Figure 1 Figure b, it can be seen that organic compounds A, B, C, and D undergo single-exponential decay in the nanosecond range of 3 - 5 ns, which indicates that organic compounds A, B, C, and D are very conducive to the rapid imaging of X-rays.

[0122] From Figure 1 Figure c, it can be seen that due to the introduction of heavy atoms in organic compounds A, B, C, and D, they have a large absorption cross-section, which is conducive to the absorption of X-rays.

[0123] From Figure 1 Figure d, it can be seen that the full width at half maximum of organic compounds A, B, C, and D is less than 70 nm, indicating that they have good narrow emission properties. At the same time, their light yields calculated by comparing with the reference scintillator are 35000 - 42400 photons / MeV, indicating that they all have a high light yield.

[0124] The above-mentioned scintillator films are prepared by the same melt quenching technique. Transfer 500 mg of the organic compound (organic compound A, B, C, or D) to a beaker, heat it at 160 °C until the raw material melts and the bubbles disappear. Subsequently, pour the liquid organic compound in the above beaker into a graphite mold, and form a film with a thickness of about 300 microns and a diameter exceeding 10 cm by rapid cooling at room temperature.

[0125] Effect Example 2

[0126] After the organic compounds A, B, C, and D prepared in Examples 1, 2, 3, and 4 are made into films, the radioluminescence intensities of different films at different X-ray dose rates are measured. The results are shown in Figure 2 , where a is the film prepared from the organic compound A prepared in Example 1, b is the film prepared from the organic compound B prepared in Example 2, c is the film prepared from the organic compound C prepared in Example 3, and d is the film prepared from the organic compound D prepared in Example 4.

[0127] From Figure 2 Figures a, b, c, and d, it can be seen that the radioluminescence intensities of organic compounds A, B, C, and D show a linear change at different X-ray dose rates. The lowest detection limit calculated from the radioluminescence intensity of 3000 is 85 - 450 μGy s -1 , indicating that they have a high X-ray detection sensitivity.

[0128] Effect Example 3

[0129] After the organic substances A, B, C, and D prepared in Examples 1, 2, 3, and 4 were made into films, the modulation transfer function (MTF) and spatial resolution of the X-ray inclined edge images of different films were measured. The results are shown in Figure 3 , where a is the film prepared from the organic substance A prepared in Example 1, b is the film prepared from the organic substance B prepared in Example 2, c is the film prepared from the organic substance C prepared in Example 3, and d is the film prepared from the organic substance D prepared in Example 4.

[0130] From Figure 3 Figures a, b, c, and d of -1 , it can be seen that the X-ray imaging spatial resolution calculated when the modulation transfer function (MTF) of the films prepared from the organic substances A, B, C, and D is 0.2 is 31.9 - 40.5 lp / mm

[0131] Effect Example 4

[0132] After the organic substances A, B, C, and D prepared in Examples 1, 2, 3, and 4 were made into films, the bright-field and dark-field photos of the pen and pen core before and after X-ray exposure of different films were measured (dose rate, 2.023 mGy / s -1 ), and the results are shown in Figure 4 .

[0133] Figure 4 are the imaging test results of the organic substances A, B, C, and D to prove their practical value. A pen with springs in different states was placed between the X-ray source and the films of the organic substances A, B, C, and D. The contour of this originally invisible spring was clearly presented on the film, while the plastic shell was almost transparent, which further proves the great potential of such HLCT scintillators in X-ray radiography.

[0134] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A hybrid localized-charge transfer excited state scintillator, characterized in that: The structural formula is shown in formula (1), formula (2), formula (3) or formula (4): Herein, m is an integer of 0 to 500, n is an integer of 0 to 500, m and n are not 0 at the same time, and m+n=5 to 500.

2. A method for preparing a hybrid localized-charge transfer excited state scintillator according to claim 1, characterized in that: The following steps are involved: The preparation method of the compound of formula (1) or formula (2) comprises: mixing compound 1, a catalyst, a base and an organic solvent under a nitrogen atmosphere, then adding compound 2 and compound 3, mixing evenly and heating to react, and performing column chromatography separation after the reaction to obtain the hybrid localized-charge transfer excited state scintillator; The compound 1 is When compound 2 is Compound 3 is The compound 1 is When both compound 2 and compound 3 are The preparation method of the compound of formula (3) or formula (4) comprises: mixing compound 1, a catalyst, a base and an organic solvent under a nitrogen atmosphere, then adding compound 4 and compound 5, heating to react after mixing evenly, and performing Soxhlet extraction after the reaction to obtain the hybrid localized-charge transfer excited state scintillator; The compound 1 is When compound 4 is Compound 5 is The compound 1 is When both compound 4 and compound 5 are 3. The preparation method according to claim 2, characterized in that: The catalyst comprises tetrakis-(triphenylphosphine)palladium(0); The base comprises K2CO3; The organic solvent includes toluene and methanol in a volume ratio of (2-5):(1-2).

4. The preparation method according to claim 2, characterized in that: The temperature of the heating reaction is 50-120° C. and the time is 12-24 hours.

5. Use of the hybrid localized-charge transfer excited state scintillator according to claim 1 as a non-destructive radiation detection material or a medical imaging material.

6. A flexible X-ray detector, characterized in that: The preparation raw materials include the hybrid localized-charge transfer excited state scintillator according to claim 1.

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