Organic small molecule material based on benzo [LMN] [2, 7] phenanthroline as acceptor unit and preparation and application thereof

Abstract

The invention relates to the technical field of organic photoelectric materials, and discloses preparation and application of an organic micromolecular luminescent material based on benzo [LMN] [2, 7] phenanthroline as an acceptor unit. By changing the types and sizes of the connected donor and acceptor units, the molecular weight, light-emitting wavelength and other material characteristics of the material can be effectively adjusted. The preparation method of the material comprises the following steps: taking benzo [LMN] [2, 7] phenanthroline as a raw material, carrying out bromination reaction to obtain an intermediate, and then reacting with respective electron donor and acceptor units to obtain a target compound. The material disclosed by the invention has the advantages of single structure, definite molecular weight, very high decomposition temperature, proper sublimation temperature, easiness in sublimation and purification and the like.

Description

Technical Field

[0001] This application relates to the field of organic light-emitting diode material technology, specifically to an organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit, and its preparation and application. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are devices that generate electroluminescence using a multilayer thin-film structure. They possess advantages such as diverse types, low manufacturing costs, and excellent photoelectric performance, attracting widespread attention for applications in solid-state lighting and flexible displays. Commonly used OLED luminescent materials can be divided into two categories: small organic molecule materials and organic polymer luminescent materials. Compared to polymer luminescent materials, small organic molecule materials are currently the mainstream mass-production solution. Small organic molecule materials have advantages such as well-defined molecular structures, simple synthesis and preparation, high material purity, easy formation of dense and pure thin films, and more mature technology, thus achieving higher device performance and stability. Currently, red, green, and blue primary color display devices based on small organic molecule luminescence have been successfully commercialized. However, due to high material preparation costs and insufficient device performance, developing efficient and low-cost novel luminescent materials has become an important issue in the field of organic electroluminescence.

[0003] In recent years, thermally activated delayed fluorescence (TADF) luminescent materials have been widely used in OLED devices. These materials achieve a theoretically 100% internal quantum efficiency through reverse system crossing (RISC), effectively overcoming the low exciton utilization problem of traditional fluorescent materials. Furthermore, they generate singlet excitons with a probability of 25% and triplet excitons with a probability of 75% under electroluminescence, thus significantly improving the luminous efficiency of OLEDs. Currently, the luminous efficiency of OLEDs fabricated based on TADF is close to commercial levels, but the fabrication cost of the materials is high, and some device performance characteristics are still not optimal.

[0004] Patent application content

[0005] To overcome the problems existing in the prior art, the primary objective of this application is to provide an organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit. This organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit can increase the fluorescence quantum efficiency (PLQY) of organic systems.

[0006] Another objective of this application is to provide a method for preparing the above-mentioned organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit.

[0007] Another objective of this application is to provide the application of the above-mentioned small organic molecule materials based on benzo[LMN][2,7]phenanthroline as the acceptor unit.

[0008] The above-mentioned objectives of this application are achieved through the following technical solutions:

[0009] An organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit, which can be used as a photoelectric functional material, has the molecular structure shown in formula (I-1) or (I-2) or (I-3):

[0010]

[0011] Wherein, R1 is selected from any one of the electron donor groups shown in (1)-(15):

[0012]

[0013]

[0014] R2 is selected from any of the electron acceptor groups shown in (16)-(25):

[0015]

[0016] Preferably, the organic small molecule material has any one of the following structural formulas:

[0017]

[0018] This application also provides a method for preparing the above-mentioned organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit, comprising the following steps:

[0019] Preparation of compound 5 (S1)

[0020] Benzo[LMN][2,7]phenanthroline was added to DMF and stirred at low temperature. Then, N-bromosuccinimide solution was slowly added dropwise to the DMF. The solution was stirred for 12 hours. Finally, the solid residue was retained by suction filtration, washed with water, and dried in an oven to obtain intermediate compound 5.

[0021]

[0022] S2. Preparation of target product compound II-1

[0023] Intermediate compounds 5 and 4-(carbazole-9-yl)phenylboronic acid pinacol ester were dissolved in a round-bottom flask containing toluene, ethanol and K2CO3 aqueous solution. After purging with argon for 15 minutes, catalyst Pd(PPh3)4 was rapidly added, and argon was purged again for 10 minutes. The reaction was then heated to 85°C and stirred for 12 hours. After cooling the reaction system to room temperature, the solvent was removed by a vacuum rotary evaporator, and the mixture was extracted three times with dichloromethane. The collected organic phase was washed with deionized water and dried with anhydrous magnesium sulfate. Further purification was carried out by silica gel column chromatography to obtain the final product compound II-1.

[0024] S2. Preparation of target product compound II-22

[0025] In a three-necked round-bottom flask equipped with a condenser, phthalazine was dissolved in dry benzene. The solution was treated with commercially available aryl magnesium bromide. Grignard reagents were prepared in THF using the usual Grignard reagent preparation method with magnesium and an intermediate. The reaction mixture was refluxed for 2 hours and stirred overnight at room temperature. The mixture was decomposed with cold saturated ammonium chloride solution and extracted with diethyl ether. The organic layers were combined, washed with water and brine, dried on anhydrous sodium sulfate, and the solvent was concentrated under vacuum. The product compound II-22 was purified by chromatography on silica gel.

[0026] Preferably, the raw material benzo[LMN][2,7]phenanthroline in step S1 can be prepared by the following method:

[0027] S11. Preparation of compound 1

[0028] In an argon atmosphere, with the catalyst PdCl2-(PPh3)2 or [PdCl2(dppf)]·CH2Cl2, Et3N or toluene was added as a solvent to the corresponding iodopyridine, followed by the addition of an appropriate alkyne reactant. After stirring for 0.2 hours, a solution of CuI in Et3N was injected into the reactant using a syringe. Stirring continued at room temperature in the dark. All solvents were removed under reduced pressure in a 70°C water bath. The residue was extracted with pentane, and the crude product was purified by silica gel flash chromatography. The product was dissolved in MeOH, and NORIT A was added to decolorize the charcoal. The mixture was stirred, filtered by gravity, and the solvent was removed under reduced pressure in a 50°C water bath for further purification. The last step was repeated with an equal amount of NORIT A and powdered anhydrous Na2SO4 in pentane. The solvent was then removed under reduced pressure at room temperature, and finally dried under dynamic vacuum to obtain compound 1.

[0029] S12. Preparation of compound 2

[0030] Compound 1, along with the catalyst dibromo[1,3,5,7-tetradecyl-1,2,3,5,6,7-hexahydrobenzo[1,2-d:4,5-d′]diimidazo(4-)-κC, was prepared. 2 Palladium, K2CO and PEG-200 were placed in a glass flask and heated to 75°C with vigorous stirring for 12 hours. The mixture was cooled to room temperature, and then a small amount of distilled water was added. The mixture was extracted with hexane or diisopropyl ether, and the upper organic phase was separated. The upper organic phase was dried on MgSO4, and then the solvent was evaporated under reduced pressure. Finally, the residue was purified by column chromatography on silica gel or recrystallized to obtain compound 2.

[0031] S13. Preparation of compound 3

[0032] At room temperature, under argon protection, a solution of 1 M TBAF in THF was added to a solution of compound 2 in dry THF. The solution was stirred overnight and quenched with 1 M HCl. The solution was evaporated, and water and CH2Cl2 were added to the solid. The aqueous phase was extracted with CH2Cl2, the organic phases were combined, washed with H2O, dried with Na2SO4 and concentrated. Finally, the residue was purified by column chromatography to obtain compound 3.

[0033] S14. Synthesis of raw material compound 4-benzo[LMN][2,7]phenanthroline

[0034] The catalyst ruthenium(1+), bis(acetonitrile)[tris(1H-pyrazole-κN] was loaded. 1) Boric acid (1-)-κN 2 ,κN 2′ ,κN 2″ A long tube containing (triphenylphosphine)-, (OC-6-23)-, hexafluorophosphate (1-)(1:1)(TpRuPPh3(CH3CN)2PF6) was dried in a vacuum for 2 hours. Then, compound 3 and 1,2-dichloroethane were added. The mixture was heated at 80°C for 24 hours, then cooled to room temperature, concentrated, and eluted by silica gel column to obtain the raw material benzo[LMN][2,7]phenanthroline.

[0035] More preferably, in step S11, the crude product is purified by silica gel flash chromatography, and the eluent is CH2Cl2.

[0036] More preferably, the eluting agent used in step S12 for column chromatography purification of the residue on silica gel is n-hexane / ethyl acetate.

[0037] More preferably, in step S13, the eluent used for the final purification of the residue by column chromatography is cyclohexane / ethyl acetate / CH2Cl2, with a volume ratio of 2.5:2.5:1.

[0038] More preferably, in step S1, benzo[LMN][2,7]phenanthroline is added to DMF and stirred at 0°C for 10 minutes.

[0039] The above-mentioned small organic molecule materials with benzo[LMN][2,7]phenanthroline as the acceptor core unit are obtained by bromination reaction to obtain intermediates, and then by reaction with various electron donor and donor groups according to the general structural formula (I-1)-(I-3).

[0040] This application also provides the applications of the above-mentioned organic small molecule materials based on benzo[LMN][2,7]phenanthroline as the acceptor unit in luminescent materials, luminescent devices, fluorescence sensors, separation materials, supramolecular self-assembly, nano-drug delivery, and smart responsive materials.

[0041] Compared with the prior art, the beneficial effects of this application are:

[0042] (1) The organic small molecule material with benzo[LMN][2,7]phenanthroline as the acceptor core unit of this application has a simple structure, a definite molecular weight, is easy to purify, has good electrochemical stability, and is easy to study its structure-activity relationship.

[0043] (2) The organic small molecule material of this application with benzo[LMN][2,7]phenanthroline as the acceptor core unit has a high fluorescence quantum yield, exhibits the properties of thermally activated delayed fluorescence, and can achieve a low efficiency roll-off.

[0044] (3) The benzo[LMN][2,7]phenanthroline of this application can also effectively control the color and efficiency of the material by changing the type and size of the donor and acceptor units coupled with it, and meet the application requirements. Attached Figure Description

[0045] Figure 1 Absorption spectra of compounds II-1 and II-22 prepared in this application in toluene solution;

[0046] Figure 2 Emission spectra of compounds II-1 and II-22 prepared in this application in toluene solution;

[0047] Figure 3 Compound II-1 prepared for this application 1 H-NMR spectrum;

[0048] Figure 4 It is compound II-1 prepared in this application. 13 C-NMR spectrum;

[0049] Figure 5 It is compound II-22 prepared in this application. 1H-NMR spectrum;

[0050] Figure 6 It is compound II-22 prepared in this application. 13 C-NMR spectrum

[0051] Figure 7 This is a luminescence quantum yield diagram of compound II-1 prepared in this application;

[0052] Figure 8 This is a luminescence quantum yield diagram of compound II-22 prepared in this application. Detailed Implementation

[0053] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0054] It should be noted that:

[0055] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0056] In this application, unless otherwise specified, percentage (%) or parts refer to weight percentage or parts relative to the composition.

[0057] Unless otherwise specified, the components or preferred components involved in this application may be combined to form new technical solutions.

[0058] In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers.

[0059] The “scope” disclosed in this application may be in the form of a lower limit and an upper limit, and may be one or more lower limits and one or more upper limits, respectively.

[0060] In this application, unless otherwise stated, the various reactions or operation steps may be performed sequentially or in a particular order. Preferably, the reaction methods described herein are performed sequentially.

[0061] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to a person skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this application.

[0062] This application provides an organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit, which can be used as a photoelectric functional material, and has the molecular structure shown in formula (I-1) or (I-2) or (I-3):

[0063]

[0064] Wherein, R1 is selected from any one of the electron donor groups shown in (1)-(15):

[0065]

[0066]

[0067] R2 is selected from any of the electron acceptor groups shown in (16)-(25):

[0068]

[0069] This application provides organic small molecule materials based on benzo[LMN][2,7]phenanthroline as the acceptor unit. By changing the type and size of the connected donor and acceptor units, the molecular weight, emission wavelength, and other material properties can be effectively adjusted. The preparation method for this type of material involves using benzo[LMN][2,7]phenanthroline as a raw material, undergoing a bromination reaction to obtain an intermediate, and then reacting it with its respective electron donor and acceptor units to obtain the target compound. The materials of this application have advantages such as simple structure, well-defined molecular weight, high decomposition temperature and appropriate sublimation temperature, and easy sublimation purification.

[0070] In some preferred embodiments, the organic small molecule material has any one of the following structural formulas: (II-1)-(II-175):

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081] In some preferred embodiments, the organic small molecule material has any one of the following structural formulas:

[0082]

[0083] This application also provides a method for preparing the above-mentioned organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit, comprising the following steps:

[0084] Preparation of compound 5 (S1)

[0085] Benzo[LMN][2,7]phenanthroline was added to DMF and stirred at low temperature. Then, N-bromosuccinimide solution was slowly added dropwise to the DMF. The solution was stirred for 12 hours. Finally, the solid residue was retained by suction filtration, washed with water, and dried in an oven to obtain intermediate compound 5.

[0086]

[0087] S2. Preparation of target product compound II-1

[0088] Intermediate compounds 5 and 4-(carbazole-9-yl)phenylboronic acid pinacol ester were dissolved in a round-bottom flask containing toluene, ethanol and K2CO3 aqueous solution. After purging with argon for 15 minutes, catalyst Pd(PPh3)4 was rapidly added, and argon was purged again for 10 minutes. The reaction was then heated to 85°C and stirred for 12 hours. After cooling the reaction system to room temperature, the solvent was removed by a vacuum rotary evaporator, and the mixture was extracted three times with dichloromethane. The collected organic phase was washed with deionized water and dried with anhydrous magnesium sulfate. Further purification was carried out by silica gel column chromatography to obtain the final product compound II-1.

[0089] S2. Preparation of target product compound II-22

[0090] In a three-necked round-bottom flask equipped with a condenser, phthalazine was dissolved in dry benzene. The solution was treated with commercially available aryl magnesium bromide. Grignard reagents were prepared in THF using the usual Grignard reagent preparation method with magnesium and an intermediate. The reaction mixture was refluxed for 2 hours and stirred overnight at room temperature. The mixture was decomposed with cold saturated ammonium chloride solution and extracted with diethyl ether. The organic layers were combined, washed with water and brine, dried on anhydrous sodium sulfate, and the solvent was concentrated under vacuum. The product compound II-22 was purified by chromatography on silica gel.

[0091] In some preferred embodiments, the raw material benzo[LMN][2,7]phenanthroline in step S1 can be prepared by the following method:

[0092] S11. Preparation of compound 1

[0093] In an argon atmosphere, with the catalyst PdCl2-(PPh3)2 or [PdCl2(dppf)]·CH2Cl2, Et3N or toluene was added as a solvent to the corresponding iodopyridine, followed by the addition of an appropriate alkyne reactant. After stirring for 0.2 hours, a solution of CuI in Et3N was injected into the reactant using a syringe. Stirring continued at room temperature in the dark. All solvents were removed under reduced pressure in a 70°C water bath. The residue was extracted with pentane, and the crude product was purified by silica gel flash chromatography. The product was dissolved in MeOH, and NORIT A was added to decolorize the charcoal. The mixture was stirred, filtered by gravity, and the solvent was removed under reduced pressure in a 50°C water bath for further purification. The last step was repeated with an equal amount of NORIT A and powdered anhydrous Na2SO4 in pentane. The solvent was then removed under reduced pressure at room temperature, and finally dried under dynamic vacuum to obtain compound 1.

[0094] S12. Preparation of compound 2

[0095] Compound 1, along with the catalyst dibromo[1,3,5,7-tetradecyl-1,2,3,5,6,7-hexahydrobenzo[1,2-d:4,5-d′]diimidazo(4-)-κC, was prepared. 2 Palladium, K2CO and PEG-200 were placed in a glass flask and heated to 75°C with vigorous stirring for 12 hours. The mixture was cooled to room temperature, and then a small amount of distilled water was added. The mixture was extracted with hexane or diisopropyl ether, and the upper organic phase was separated. The upper organic phase was dried on MgSO4, and then the solvent was evaporated under reduced pressure. Finally, the residue was purified by column chromatography on silica gel or recrystallized to obtain compound 2.

[0096] S13. Preparation of compound 3

[0097] At room temperature, under argon protection, a solution of 1 M TBAF in THF was added to a solution of compound 2 in dry THF. The solution was stirred overnight and quenched with 1 M HCl. The solution was evaporated, and water and CH2Cl2 were added to the solid. The aqueous phase was extracted with CH2Cl2, the organic phases were combined, washed with H2O, dried with Na2SO4 and concentrated. Finally, the residue was purified by column chromatography to obtain compound 3.

[0098] S14. Synthesis of raw material compound 4-benzo[LMN][2,7]phenanthroline

[0099] The catalyst ruthenium(1+), bis(acetonitrile)[tris(1H-pyrazole-κN] was loaded.1) Boric acid (1-)-κN 2 ,κN 2′ ,κN 2″ A long tube containing (triphenylphosphine)-, (OC-6-23)-, hexafluorophosphate (1-)(1:1)(TpRuPPh3(CH3CN)2PF6) was dried in a vacuum for 2 hours. Then, compound 3 and 1,2-dichloroethane were added. The mixture was heated at 80°C for 24 hours, then cooled to room temperature, concentrated, and eluted by silica gel column to obtain the raw material benzo[LMN][2,7]phenanthroline.

[0100] In some preferred embodiments, in step S11, the crude product is purified by silica gel flash chromatography, and the eluent is CH2Cl2.

[0101] In some preferred embodiments, the eluting apparatus used in step S12 for column chromatography purification of the residue on silica gel is n-hexane / ethyl acetate.

[0102] In some preferred embodiments, the eluent used in step S13 for the final purification of the residue by column chromatography is cyclohexane / ethyl acetate / CH2Cl2, with a volume ratio of 2.5:2.5:1.

[0103] In some preferred embodiments, in step S1, benzo[LMN][2,7]phenanthroline is added to DMF and stirred at 0°C for 10 minutes.

[0104] This application also provides the applications of the above-mentioned small organic molecule materials based on benzo[LMN][2,7]phenanthroline as the acceptor unit in their use as luminescent materials, luminescent devices, fluorescence sensors, separation materials, supramolecular self-assembly, nanomedicine delivery systems, and smart responsive materials.

[0105] The preparation methods of organic small molecule materials II-1 and II-22 based on benzo[LMN][2,7]phenanthroline as the acceptor unit will be described in detail below.

[0106] Example 1

[0107] In this embodiment, the raw material benzo[LMN][2,7]phenanthroline, also known as compound 4, is prepared. Its structural formula and synthetic route are shown in the figure below:

[0108]

[0109] The preparation method of compound 1 (S11) is as follows:

[0110] Under argon atmosphere, in the presence of catalysts PdCl2-(PPh3)2 or [PdCl2(dppf)]·CH2Cl2, Et3N or toluene is added as a solvent to the corresponding iodopyridine, followed by the addition of an appropriate alkyne reactant. After stirring for 0.2 hours, a CuI solution in Et3N is injected into the reactant using a syringe, and stirring continues for 5-7 days at room temperature in the dark. The reaction will sequentially form gray, brown, or yellow precipitates. All solvents are then removed under reduced pressure in a 70°C water bath, and the residue is extracted with 5 × 30 mL of pentane. The extract is then gravity filtered, and the solvent is removed under reduced pressure in a water bath at room temperature. The crude product is purified by silica gel flash chromatography, eluting with CH2Cl2. The product is dissolved in 20-30 mL of MeOH, and 0.05-0.25 g of NORIT A decolorizing charcoal is added and stirred. The mixture is then gravity filtered, and the solvent is removed under reduced pressure in a 50°C water bath for further purification. The last step was repeated using equal amounts of NORIT A and powdered anhydrous Na₂SO₄ (1-3 g) in 30-60 mL of pentane, followed by solvent removal under reduced pressure at room temperature. Finally, the mixture was dried under a dynamic vacuum of 0.01 mmHg to give compound 1 in 91% yield. Molecular weight m / z: 252.99; Elemental analysis results: C, 47.25; H, 4.76; Br, 31.43; N, 5.51; Si, 11.05.

[0111] The preparation method of compound 2 (S12) is as follows:

[0112] Compound 1 (1 mmol, 0.2503 g), catalyst dibromo[1,3,5,7-tetradecyl-1,2,3,5,6,7-hexahydrobenzo[1,2-d:4,5-d′]diimidazolo(4-)-κC 2 Palladium (0.5 mol%), K₂CO₃ (2 mmol, 0.2764 g), and PEG-200 (2 ml) were placed in a glass flask and heated at 75 °C with vigorous stirring for 12 hours. The reaction was monitored by TLC. The mixture was cooled to room temperature, and a small amount of distilled water was added. The mixture was extracted with n-hexane or diisopropyl ether, and the upper organic phase was separated and dried on MgSO₄. The solvent was then evaporated under reduced pressure. Finally, the residue was purified by column chromatography on silica gel using n-hexane / ethyl acetate as eluent, or recrystallized to give compound 2 in 75% yield. Molecular weight m / z: 348.15; elemental analysis results: C, 68.91; H, 6.94; N, 8.04; Si, 16.11.

[0113] The preparation method of compound 3 (S13) is as follows:

[0114] At room temperature, under argon protection, a solution of 1M TBAF in THF (5.35 mmol, 5.3 mL) was added to a solution of compound 2 (2.43 mmol, 846 mg) in dry THF (10 mL). The solution was stirred overnight and quenched with 1M HCl (3 mL) to evaporate the solvent. Water (15 mL) and CH2Cl2 (20 mL) were added to the solid, and the aqueous phase was extracted with CH2Cl2 (3 × 15 mL). The organic phases were combined, washed with H2O (15 mL), dried over Na2SO4, and concentrated. Finally, the residue was purified by column chromatography (SiO2, cyclohexane / ethyl acetate / CH2Cl2, 2.5:2.5:1) to give compound 3 in 74% yield. Molecular weight m / z: 204.07; elemental analysis results: C, 82.33; H, 3.95; N, 13.72.

[0115] S14. Synthesis of raw material compound 4-benzo[LMN][2,7]phenanthroline:

[0116] The catalyst ruthenium(1+), bis(acetonitrile)[tris(1H-pyrazole-κN] was loaded. 1) Boric acid (1-)-κN 2 ,κN 2′ ,κN 2″ A long tube containing (triphenylphosphine)-, (OC-6-23)-, hexafluorophosphate (1-)(1:1)(TpRuPPh3(CH3CN)2PF6) (0.05 mmol, 41.1 mg) was dried under vacuum for 2 hours, followed by the addition of compound 3 (0.54 mmol, 110.2 mg) and 1,2-dichloroethane (10.8 mL). The mixture was heated at 80 °C for 24 hours and then cooled to room temperature. After concentration, the mixture was eluted by silica gel column chromatography to give the starting material benzo[LMN][2,7]phenanthroline in 75% yield. Molecular weight m / z: 204.23; elemental analysis results: C, 82.36; H, 3.97; N, 13.75.

[0117] Example 2

[0118] In this embodiment, intermediate compound 5 was prepared, and its structural formula and synthetic route are shown in the figure below:

[0119]

[0120] The specific reaction steps are as follows:

[0121] Compound 4, benzo[LMN][2,7]phenanthroline (20 mmol, 4.08 g), was added to DMF and stirred at 0 °C for 10 minutes. Then, N-bromosuccinimide solution (21 mmol, 7.48 g) was slowly added dropwise to the DMF. The solution was stirred for 12 hours, and then 100 mL was added to the solution. Finally, the solid residue was retained by suction filtration, washed with water, and dried in an oven to give intermediate compound 5 in 90% yield. Product molecular formula: C 14 H6Br2N2; molecular weight m / z: 361.89; elemental analysis results: C, 46.45; H, 1.67; Br, 44.14; N, 7.74.

[0122] Example 3

[0123] In this embodiment, compound II-1 was prepared, and its structural formula and synthetic route are shown in the figure below:

[0124]

[0125] Compound 5

[0126] The specific reaction steps are as follows:

[0127] Intermediate compound 5 (1.14 mmol, 413 mg) and 4-(carbazole-9-yl)phenylboronic acid pinacol ester (2.85 mmol, 1052 mg) were dissolved in a 250 mL round-bottom flask containing 60 mL toluene, 25 mL ethanol, and 20 mL of K₂CO₃ aqueous solution (2 M). After purging with argon for 15 min, catalyst Pd(PPh₃)₄ (0.057 mmol, 66 mg) was rapidly added, followed by purging with argon for another 10 min. The reaction was then heated to 85 °C and stirred for 12 h. After cooling to room temperature, the solvent was removed by rotary evaporation under vacuum, and the mixture was extracted three times with dichloromethane (DCM). The collected organic phase was washed three times with deionized water and dried over anhydrous magnesium sulfate (MgSO₄). Further purification was performed by silica gel column chromatography to give product compound II-1 in 63% yield. Product molecular formula: C 50 H 30 N4; molecular weight m / z: 686.25; elemental analysis results: C, 87.44; H, 4.40; N, 8.16.

[0128] Example 4

[0129] In this embodiment, compound II-22 was prepared, and its structural formula and synthetic route are shown in the figure below:

[0130]

[0131] Compound 5

[0132] In a three-necked round-bottom flask equipped with a condenser, phthalazine (7.5 mmol, 975 mg) was dissolved in dry benzene (30 mL). The solution was treated with commercially available arylmagnesium bromide (30 mmol, 5.4396 g). The Grignard reagent was prepared in THF with magnesium and an intermediate using a standard Grignard reagent preparation method. The reaction mixture was refluxed for 2 hours. The reaction mixture was stirred overnight at room temperature. The mixture was decomposed with cold saturated ammonium chloride solution (50 mL). The mixture was extracted with diethyl ether (3 x 100 mL), and the organic layers were combined. The organic layers were washed with water (30 mL) and brine (30 mL). The organic layers were dried over anhydrous sodium sulfate. The solvent was concentrated under vacuum. Chromatographic purification on silica gel yielded compound II-22 in 60% yield. Product molecular formula: C 30 H 16 N6; molecular weight m / z: 460.14; elemental analysis results: C, 78.25; H, 3.50; N, 18.25.

[0133] Performance testing

[0134] The organic small molecule materials II-1 and II-22, prepared in Examples 3 and 4, based on benzo[LMN][2,7]phenanthroline as the acceptor unit, were characterized and their performance was tested. The results are as follows: Figures 1-6 As shown.

[0135] The testing method is as follows:

[0136] Compound structure determination: Bruker 500MHz superconducting nuclear magnetic resonance spectrometer, deuterated chloroform as solvent;

[0137] Ultraviolet absorption spectroscopy detection: A Shimadzu UV-2700 UV-Vis spectrophotometer was used, with a scanning range of [missing information].

[0138] 250–600 nm;

[0139] Emission spectroscopy detection: A steady-state / transient fluorescence spectrometer (FLS980) was used with an excitation wavelength of 365 nm.

[0140] The test temperature was 300K.

[0141] The test results are as follows:

[0142] from Figure 1 , 2 The image shows the UV absorption and emission patterns of compound II-1 prepared in Example 3 of this application. Figure 1 As can be seen from the data, the ultraviolet absorption peak of compound II-1 prepared in this application is at a wavelength of 367 nm; from... Figure 2As can be seen, the fluorescence emission peak of compound II-1 is at 436 nm, and the half-width of compound II-1 is 67 nm, which means it has high color purity blue light emission and can achieve short-wavelength emission.

[0143] like Figure 3 As shown, the characteristic wavenumber (ppm) of compound II-1 prepared in Example 3 is 1 H NMR(500MHz,Chloroform-d)δ9.13(s,1H),8.51(d,J=7.9Hz,1H),8.16-8.06(m,2H),7.97(d,J =7.9Hz,1H),7.83-7.77(m,2H),7.66-7.58(m,2H),7.55-7.50(m,2H),7.36-7.30(m,1H),7.30-

[0144] 7.25 (m, 3H). The peak energies of the 1H molecular magnetic resonance spectrum correspond one-to-one with the target product, and the number is reasonable. This indicates that Example 1 prepared compound II-1, an organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit, and the compound has a simple structure and high purity.

[0145] The carbon NMR spectrum of compound II-1 prepared in Example 3 is as follows: Figure 4 As shown, it can be seen that: 13 C10 NMR (100MHz, Chloroform-d) δ 148.71, 147.10, 140.45, 139.23, 134.39, 129.09, 128.10, 127.22, 126.31, 125.88, 125.17, 123.32, 120.67, 120.26, 110.52. The molecular carbon spectrum peak energies correspond one-to-one with the target product, and the number is reasonable; indicating that the compound II-1 prepared in Example 3 has a simple structure and high purity.

[0146] Figure 1 , 2 The UV absorption and emission spectrum of compound II-22 prepared in Example 4 of this application is shown. Figure 1 As can be seen from the data, the ultraviolet absorption peak of compound II-22 prepared in this application is at a wavelength of 367 nm; from... Figure 2 As can be seen, the fluorescence emission peak of compound II-22 is at 439 nm, and the half-width of compound II-22 is 68 nm, which means it has high color purity blue light emission and can achieve short-wavelength emission.

[0147] like Figure 5 As shown, the characteristic wavenumber (ppm) of compound II-22 prepared in Example 4 is 1¹H NMR (500MHz, Chloroform-d) δ 9.73 (s, 1H), 9.52 (d, J = 2.0Hz, 1H), 8.84 (d, J = 7.9Hz, 1H), 8.08 (dd, J = 8.6, 1.5Hz, 1H), 8.00 (d, J = 7.9Hz, 1H), 7.96 (d, J = 8.0Hz, 1H), 7.75 (ddd, J = 8.4, 7.1, 1.4Hz, 1H), 7.70 (ddd, J = 8.2, 7.0, 1.5Hz, 1H). The ¹H molecular magnetic resonance peak energies correspond one-to-one with the target product, and the number is reasonable. This indicates that Example 1 prepared compound II-22, an organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit, and the compound has a simple structure and high purity.

[0148] The carbon NMR spectrum of compound II-22 prepared in Example 4 is as follows: Figure 6 As shown, it can be seen that: 13 C10 NMR (100MHz, Chloroform-d) δ 153.97, 151.51, 148.13, 147.36, 135.11, 134.03, 131.18, 128.74, 128.45, 127.82, 126.56, 125.67, 124.99, 124.19, 122.73. The molecular carbon spectrum peak energies correspond one-to-one with the target product, and the number is reasonable; indicating that the compound II-22 prepared in Example 4 has a simple structure and high purity.

[0149] Figure 7 , 8 The figures show the luminescence quantum yields of compounds II-1 and II-22 prepared in Examples 3 and 4 of this application. It can be seen that compounds II-1 and II-22 prepared in this application have high fluorescence quantum efficiencies of 74.48% and 83.95%, respectively, exhibiting significant thermally activated delayed fluorescence properties.

[0150] The small organic molecule materials based on benzo[LMN][2,7]phenanthroline as the acceptor unit in this application can effectively adjust the material properties such as molecular weight and emission wavelength by changing the type and size of the connected donor and acceptor units. The chemical structure of the acceptor unit based on benzo[LMN][2,7]phenanthroline is as follows: Figure 3 This type of material is shown in the diagram. The preparation method involves using benzo[LMN][2,7]phenanthroline as a raw material, undergoing a bromination reaction to obtain an intermediate, and then reacting it with its respective electron donor and acceptor units to obtain the target compound. The materials in this application have advantages such as simple structure, well-defined molecular weight, high decomposition temperature and appropriate sublimation temperature, and easy sublimation purification.

[0151] Compared with the prior art, the beneficial effects of this application are:

[0152] (1) The organic small molecule material with benzo[LMN][2,7]phenanthroline as the acceptor core unit of this application has a simple structure, a definite molecular weight, is easy to purify, has good electrochemical stability, and is easy to study its structure-activity relationship.

[0153] (2) The organic small molecule material of this application with benzo[LMN][2,7]phenanthroline as the acceptor core unit has a high fluorescence quantum yield, exhibits the properties of thermally activated delayed fluorescence, and can achieve a low efficiency roll-off.

[0154] (3) The benzo[LMN][2,7]phenanthroline of this application can also effectively control the color and efficiency of the material by changing the type and size of the donor and acceptor units coupled with it, and meet the application requirements.

[0155] This application provides a class of small organic molecule materials based on benzo[LMN][2,7]phenanthroline as the acceptor unit for applications in fields such as luminescent materials, luminescent devices, fluorescence sensors, separation materials, supramolecular self-assembly, nanomedicine delivery, and smart responsive materials.

[0156] Meanwhile, this application realizes the controllable preparation of small organic molecule materials based on benzo[LMN][2,7]phenanthroline as the acceptor unit; the preparation cost is low, the raw material sources are wide, and large-scale production can be realized, which has broad commercial prospects.

[0157] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0158] Although several embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. An organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit, which can be used as a photoelectric functional material, characterized in that, It has the molecular structure shown in formula (I-1), (I-2), or (I-3) as follows: Wherein, R1 is selected from any one of the electron donor groups shown in (1)-(15): R2 is selected from any of the electron acceptor groups shown in (16)-(25):

2. The organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit according to claim 1, characterized in that, The organic small molecule material has any one of the following structural formulas (II-1)-(II-175):

3. The organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit according to claim 2, characterized in that, The organic small molecule material has any one of the following structural formulas:

4. The method for preparing the organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit as described in claim 3, characterized in that, Includes the following steps: Preparation of compound 5 (S1) Benzo[LMN][2,7]phenanthroline was added to DMF and stirred at low temperature. Then, N-bromosuccinimide solution was slowly added dropwise to the DMF. The solution was stirred for 12 hours. Finally, the solid residue was retained by suction filtration, washed with water, and dried in an oven to obtain intermediate compound 5. S2. Preparation of target product compound II-1 Intermediate compounds 5 and 4-(carbazole-9-yl)phenylboronic acid pinacol ester were dissolved in a round-bottom flask containing toluene, ethanol and K2CO3 aqueous solution. After purging with argon for 15 minutes, catalyst Pd(PPh3)4 was rapidly added, and argon was purged again for 10 minutes. The reaction was then heated to 85°C and stirred for 12 hours. After cooling the reaction system to room temperature, the solvent was removed by a vacuum rotary evaporator, and the mixture was extracted three times with dichloromethane. The collected organic phase was washed with deionized water and dried with anhydrous magnesium sulfate. Further purification was carried out by silica gel column chromatography to obtain the final product compound II-1. S2. Preparation of target product compound II-22 In a three-necked round-bottom flask equipped with a condenser, phthalazine was dissolved in dry benzene. The solution was treated with commercially available aryl magnesium bromide. Grignard reagents were prepared in THF using the usual Grignard reagent preparation method with magnesium and an intermediate. The reaction mixture was refluxed for 2 hours and stirred overnight at room temperature. The mixture was decomposed with cold saturated ammonium chloride solution and extracted with diethyl ether. The organic layers were combined, washed with water and brine, dried on anhydrous sodium sulfate, and the solvent was concentrated under vacuum. The product compound II-22 was purified by chromatography on silica gel.

5. The method for preparing organic small molecule materials based on benzo[LMN][2,7]phenanthroline as the acceptor unit according to claim 4, characterized in that, The raw material benzo[LMN][2,7]phenanthroline in step S1 can be prepared by the following method: S11. Preparation of compound 1 In an argon atmosphere, in the presence of catalysts PdCl2-(PPh3)2 or [PdCl2(dppf)]·CH2Cl2, Et3N or toluene was added as a solvent to the corresponding iodopyridine, followed by the addition of an appropriate alkyne reactant. After stirring for 0.2 hours, a solution of CuI in Et3N was injected into the reactant using a syringe. Stirring continued at room temperature in the dark. All solvents were removed under reduced pressure in a 70°C water bath. The residue was extracted with pentane, and the crude product was purified by silica gel flash chromatography. The product was dissolved in MeOH, and NORIT A decolorizing charcoal was added and stirred. The mixture was then gravity filtered, and the solvent was removed under reduced pressure in a 50°C water bath for further purification. The last step was repeated with equal amounts of NORITA and powdered anhydrous Na2SO4 in pentane, and the solvent was removed under reduced pressure at room temperature. Finally, the mixture was dried under dynamic vacuum to obtain compound 1. S12. Preparation of compound 2 Compound 1, along with the catalyst dibromo[1,3,5,7-tetradecyl-1,2,3,5,6,7-hexahydrobenzo[1,2-d:4,5-d′]diimidazo(4-)-κC, was prepared. 2 Palladium, K2CO and PEG-200 were placed in a glass flask and heated to 75°C with vigorous stirring for 12 hours. The mixture was cooled to room temperature, and then a small amount of distilled water was added. The mixture was extracted with hexane or diisopropyl ether, and the upper organic phase was separated. The upper organic phase was dried on MgSO4, and then the solvent was evaporated under reduced pressure. Finally, the residue was purified by column chromatography on silica gel or recrystallized to obtain compound 2. S13. Preparation of compound 3 At room temperature, under argon protection, a solution of 1 M TBAF in THF was added to a solution of compound 2 in dry THF. The solution was stirred overnight and quenched with 1 M HCl. The solution was evaporated, and water and CH2Cl2 were added to the solid. The aqueous phase was extracted with CH2Cl2, the organic phases were combined, washed with H2O, dried with Na2SO4 and concentrated. Finally, the residue was purified by column chromatography to obtain compound 3. S14. Synthesis of raw material compound 4-benzo[LMN][2,7]phenanthroline The catalyst ruthenium(1+), bis(acetonitrile)[tris(1H-pyrazole-κN] was loaded. 1) Boric acid (1-)-κN 2 ,κN 2′ ,κN 2″ A long tube containing (triphenylphosphine)-, (OC-6-23)-, hexafluorophosphate (1-)(1:1)(TpRuPPh3(CH3CN)2PF6) was dried in a vacuum for 2 hours. Then, compound 3 and 1,2-dichloroethane were added. The mixture was heated at 80°C for 24 hours, then cooled to room temperature, concentrated, and eluted by silica gel column to obtain the raw material benzo[LMN][2,7]phenanthroline.

6. The method for preparing organic small molecule materials based on benzo[LMN][2,7]phenanthroline as the acceptor unit according to claim 5, characterized in that, In step S11, the crude product is purified by silica gel flash chromatography, and the eluent is CH2Cl2.

7. The method for preparing organic small molecule materials based on benzo[LMN][2,7]phenanthroline as the acceptor unit according to claim 5, characterized in that, In step S12, the eluting agent used for column chromatography purification of the residue on silica gel is n-hexane / ethyl acetate.

8. The method for preparing organic small molecule materials based on benzo[LMN][2,7]phenanthroline as the acceptor unit according to claim 5, characterized in that, In step S13, the eluent used for the final purification of the residue by column chromatography is cyclohexane / ethyl acetate / CH2Cl2, with a volume ratio of 2.5:2.5:

1.

9. The method for preparing organic small molecule materials based on benzo[LMN][2,7]phenanthroline as the acceptor unit according to claim 4, characterized in that, In step S1, benzo[LMN][2,7]phenanthroline is added to DMF and stirred at 0°C for 10 minutes.

10. The application of the organic small molecule material based on benzo[LMN][2,7]phenanthroline as the acceptor unit as described in claim 1 in the fields of luminescent materials, luminescent devices, fluorescence sensors, separation materials, supramolecular self-assembly, nanomedicine delivery, and smart responsive materials.

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