A nitrogen-boron dual-doped spirocyclic compound, its preparation method and application

Abstract

This invention relates to a nitrogen-boron dual-doped spirocyclic compound having the chemical structure shown in formula (I) or formula (II). The nitrogen-boron dual-doped spirocyclic compound of this invention exhibits high photoluminescence quantum efficiency and a small singlet-triplet energy level difference. Through proper control of the donor and acceptor units, this compound can achieve multicolor emission. It also possesses good solubility, film-forming properties, and thin film morphology stability. Based on the nitrogen-boron heterospirocyclic compound of this invention, solution-processed devices with low turn-on voltage and high external quantum efficiency exhibit excellent device performance and offer significant advantages for applications.

Description

Technical Field

[0001] This invention relates to the field of organic electroluminescent materials technology, specifically to a nitrogen-boron dual-doped spirocyclic compound, its preparation method, and its applications. Background Technology

[0002] Spirocyclic compounds are composed of two molecular segments connected by a sp. 3 Formed by the connection of hybrid carbon atoms, the spirocyclic framework allows for complete separation of frontier molecular orbitals due to its spatial effects. The perpendicular alignment of two molecular segments within the spirocyclic structure suppresses nonradiative transitions, preventing severe aggregation concentration quenching. The rigid spirocyclic structure enables highly efficient space charge transfer and high photoluminescence quantum efficiency. Spirocyclic compounds possess a unique three-dimensional structure, exhibiting excellent thermal and morphological stability. Therefore, spirocyclic compounds are highly favored by researchers and have become one of the most important classes of organic semiconductor materials.

[0003] Thermally activated delayed fluorescence (TEF) is a process of thermally activated re-emission of triplet excitons. After thermal activation, the triplet exciton transitions to a higher vibrational energy level, then via anti-intersystem crossing to a vibrational energy level close to that of a singlet state, producing delayed fluorescence through radiative transition. Its lifetime is typically on the order of μs. In contrast, singlet excitons rapidly decay from the singlet state to the ground state, directly emitting fluorescence as transient fluorescence, with a lifetime on the order of ns. TEF materials are the third generation of purely organic light-emitting materials, developed after traditional fluorescent materials and noble metal phosphorescent materials. TEF materials not only possess the advantages of traditional fluorescent and phosphorescent materials but also avoid the drawbacks of heavy metal involvement, and have attracted widespread attention in recent years.

[0004] In recent years, Professor Jiang Zuoquan and others proposed the concept of space-confined charge transfer based on spirocyclic structures, and used this mechanism to prepare highly efficient organic light-emitting materials with a donor-acceptor-donor π-stacking structure. Professor Wang Yue linked spirocyclic electron donors and acceptors through sterically hindered groups to construct high-performance deep blue photoluminescent materials with thermally activated delayed fluorescence properties. Clearly, spirocyclic compounds, due to their unique geometric and electronic structures, have great application potential in the field of thermally activated delayed fluorescence light-emitting materials. However, the modulation of the luminescent properties of materials through the interaction between donors and acceptors and its structure-activity relationship have not yet been systematically studied.

[0005] The p-π* conjugation between the empty p orbitals of boron and the neighboring π-conjugated system significantly lowers the LUMO energy level of the π-conjugated system, thus endowing it with unique optoelectronic properties. Based on these characteristics, researchers have developed many boron-containing polycyclic aromatic hydrocarbons (PAHs) with thermally activated delayed fluorescence properties. However, research on introducing boron atoms into the spirocyclic backbone and utilizing the acceptor properties of boron-containing PAHs to modulate the luminescence properties of thermally activated delayed fluorescence materials is extremely limited. Summary of the Invention

[0006] To overcome the aforementioned shortcomings and deficiencies of existing technologies, the inventors designed and synthesized a series of boron- and nitrogen-doped spirocyclic molecules. Through effective control of the donor and acceptor units, they developed organic small-molecule luminescent materials with thermally activated delayed fluorescence properties. The nitrogen- and boron-doped spirocyclic molecules provided by this invention exhibit high fluorescence quantum efficiency, good solubility, and thermal stability. OLED devices prepared using these molecules as the luminescent layer via solution processing exhibit low turn-on voltage and a maximum external quantum efficiency as high as 22%, demonstrating their application potential in the field of OLED luminescent materials.

[0007] The first objective of this invention is to provide a nitrogen-boron dual-doped spirocyclic compound having the chemical structure shown in formula (I) or formula (II):

[0008]

[0009] In general formulas (I) and (II), R1, R2, R3, R4, R5, R6, and R7 are selected from one or more of the following substituents: hydrogen atom, halogen atom, alkyl group containing 1-4 carbon atoms, haloalkyl group, nitro group, sulfonic acid group, cyano group, formyl group, vinyl group, alkyl acyl group, and alkyl sulfide group; X is O, S, N, or C(R8)2, wherein R8 is an alkyl group containing 1-4 carbon atoms, or X is absent;

[0010] In compounds of formula (II), rings A1 and A2 are independently *-CR a =CR a -CR a =CR a -*,R a The substituent is selected from one or more of the following: hydrogen atom, halogen atom, alkyl group containing 1-4 carbon atoms, haloalkyl group, nitro group, sulfonic acid group, cyano group, formyl group, vinyl group, alkyl acyl group and alkyl sulfide group and phenyl fusion site; or one of ring A1 and ring A2 is absent;

[0011] In the compounds of formula (I) and formula (II), R1 and R2 are not both H.

[0012] Further, the halogen atom is selected from F, Cl, Br or I; the alkyl group containing 1-4 carbon atoms is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl or tert-butyl; the haloalkyl group is selected from CF3, CCl3, CBr3, CH2F, CHF2, CH2CF3 or CF2CF3.

[0013] The nitrogen-boron dual-doped spirocyclic compounds have the following structures:

[0014]

[0015]

[0016] The second objective of this invention is to provide a method for preparing the above-mentioned nitrogen-boron dual-doped spirocyclic compound, the synthetic route of which is as follows:

[0017]

[0018] The preparation method of the above compound includes the following steps:

[0019] Preparation of compound (I): Under an inert atmosphere, the reaction system of intermediate A′ solution was cooled to a low temperature of -80℃ to -60℃, n-butyllithium was added, and the mixture was stirred at a low temperature for 1-2 hours. Then, intermediate B′ solution was slowly added. After the addition was completed, the temperature was slowly raised to room temperature and stirred overnight. After post-treatment, glacial acetic acid and hydrochloric acid were added, and the mixture was heated under reflux for 5-10 hours. The mixture was then purified to obtain compound (I).

[0020] Preparation of compound (II): Under an inert atmosphere, the solution of intermediate A″ was cooled to a low temperature of -80℃ to -60℃, n-butyllithium was added, and the mixture was stirred at a low temperature for 1-2 hours. The solution of intermediate B″ was slowly added, and after the addition was completed, the temperature was slowly raised to room temperature and stirred overnight. After post-treatment, glacial acetic acid and hydrochloric acid were added, and the mixture was heated under reflux for 5-10 hours. The mixture was then purified to obtain compound (II).

[0021] Further, the solvent used in the solutions of intermediate A′ or A″, and intermediate B′ or B″, is at least one of tetrahydrofuran and diethyl ether; the slow heating is carried out at a heating rate of 2-3 °C / min; the post-treatment involves quenching the reaction (e.g., adding a saturated ammonium chloride solution), solvent extraction of the aqueous phase (solvents such as dichloromethane, chloroform, and ethyl acetate), washing of the organic phase (washing with a saturated sodium chloride solution), drying (treatment with a conventional desiccant, such as anhydrous sodium sulfate), and rotary evaporation to remove the solvent. The purification method is well known in the art, such as recrystallization or column chromatography purification.

[0022] Further, the molar ratio of intermediate A′ (or intermediate A″), n-butyllithium, and intermediate B′ (or intermediate B″) is 1:1-1.2:1-1.2, preferably, n-butyllithium and intermediate B′ (or intermediate B″) are slightly in excess; further, the volume of glacial acetic acid added is 50-60 times (mL / g) of the mass of intermediate A′ (or intermediate A″), and the volume of hydrochloric acid added is 3-5 times (mL / g) of the mass of intermediate A.

[0023] The third objective of this invention is to provide an organic electroluminescent device comprising the aforementioned boron- and nitrogen-doped spirocyclic compound as the light-emitting layer material. Attached Figure Description

[0024] Figure 1 It is the UV-Vis absorption spectrum of boron and nitrogen-doped spirocyclic compounds. Figure 1 a) and fluorescence emission spectrum ( Figure 1 b);

[0025] Figure 2 These are emission spectra and fluorescence images of boron- and nitrogen-doped spirocyclic compounds in different solvents;

[0026] Figure 3 These are the cyclic voltammetry curves of boron- and nitrogen-doped spirocyclic compounds;

[0027] Figure 4 These are the transient fluorescence spectra of boron- and nitrogen-doped spirocyclic compounds in different solvents under anaerobic and aerobic conditions, respectively.

[0028] Figure 5 The emission spectrum and transient fluorescence decay curve of a 5wt% doped film of a boron and nitrogen dual-doped spirocyclic compound are shown.

[0029] Figure 6 These are the temperature-dependent transient fluorescence decay curves of boron and nitrogen-doped spirocyclic compounds in the doped film, and the k-values ​​in the doped film. RISC Relationship with temperature;

[0030] Figure 7 This is a thermogravimetric analysis (TGA) diagram of a boron-nitrogen dual-doped spirocyclic compound;

[0031] Figure 8 This is the electroluminescence spectrum of a boron-nitrogen dual-doped spirocyclic compound as the light-emitting layer device;

[0032] Figure 9 This is a graph showing the current density-voltage-luminance relationship of a boron-nitrogen dual-doped spirocyclic compound as the light-emitting layer device.

[0033] Figure 10 The external quantum efficiency-luminescence curves of boron-nitrogen dual-doped spirocyclic compounds used as the light-emitting layer device;

[0034] Figure 11 The current density-luminous intensity curves are for boron and nitrogen-doped spirocyclic compounds used as the light-emitting layer.

[0035] Figure 12 This is a performance illustration based on boron and nitrogen dual-doped spirocyclic compounds. Detailed Implementation

[0036] Preparation Example 1

[0037] First, name the compound in intermediate B′ with R1, R2, and R3 as CF3 and R4 and R5 as H as [missing information]. FMesB- F The preparation method of AQ is as follows:

[0038]

[0039] (1) Synthesis of compound 1a

[0040] 1-Bromo-2-iodo-4-(trifluoromethyl)benzene (7.02 g, 20.0 mmol) was placed in a 250 mL reaction flask, and the system was evacuated three times under a nitrogen atmosphere. 120 mL of dry tetrahydrofuran was then added. The flask was placed in a cryostat at -15 °C, and then isopropyl magnesium chloride lithium chloride (1.3 M in THF, 16.9 mL, 22.0 mmol) was slowly added dropwise. The reaction mixture was stirred at -15 °C for 2 hours. The flask was then placed at -78 °C, and o-bromobenzaldehyde (4.07 g, 22.0 mmol) was slowly added dropwise using a syringe. After the addition was complete, the mixture was slowly brought to room temperature and stirred overnight. The reaction was quenched with 6 M HCl until the aqueous layer showed litmus red. 50 mL of water was added, and the aqueous phase was extracted three times with ethyl acetate. The combined organic phases were washed with saturated NaCl solution and dried over anhydrous Na₂SO₄. The solvent was removed by rotary evaporation, and the crude product was purified by column chromatography with petroleum ether:ethyl acetate = 8:1 as the eluent to give 7.1 g of white solid 1a, with a yield of 87%.

[0041] 1 H NMR (700MHz, CDCl3) δ7.79(s,1H),7.70(d,J=8.4Hz,1H),7.61(d,J=7.7Hz,1H),7.46(d,J=8.4Hz,1H),7.30 (t,J=7.7Hz,1H),7.21(t,J=8.4Hz,1H),7.12(d,J=7.7Hz,1H),6.43(d,J=4.2Hz,1H),2.66(d,J=4.2Hz,1H). 13 C NMR (176MHz, CDCl3) δ142.30, 140.26, 133.65, 133.30, 130.25 (q, J = 33.4Hz), 130.02, 128.74, 128.05 ,127.37,126.12(q,J=3.5Hz),125.62(q,J=3.5Hz),124.36,123.93(q,J=272.8Hz),74.08.[M+H–H2O] + calcd.for C 14 H 19 Br2F3O,392.8924; found:392.8913.

[0042] (2) Synthesis of compound 1b

[0043] Compound 1a (6.2 g, 15.1 mmol) was placed in a 250 mL round-bottom flask, 120 mL of acetic acid was added, followed by hydroiodic acid (9.7 mL, 57% in H₂O, 60.5 mmol). The reaction mixture was then placed in an oil bath at 120 °C and refluxed for 2 hours. After cooling to room temperature, the reaction was quenched with saturated sodium sulfite solution, and the reaction solution changed from black to deep yellow. The mixture was then diluted with 100 mL of water, extracted three times with dichloromethane, and the combined organic phases were cooled to 0 °C. NaOH aqueous solution (1 M) was slowly added until litmus blue was obtained. The organic phase was washed with saturated NaCl solution and dried over anhydrous Na₂SO₄. The solvent was removed by rotary evaporation, and the concentrated liquid was purified by column chromatography using petroleum ether as the eluent to give 4.8 g of colorless liquid 1b, with a yield of 80%.

[0044] 1 H NMR (700MHz, CDCl3) δ7.73(d,J=8.4Hz,1H),7.62(d,J=7.7Hz,1H),7.37(d,J=8.4Hz ,1H),7.26-7.23(m,2H),7.15(t,J=7.7Hz,1H),6.98(d,J=7.7Hz,1H),4.24(s,2H). 13 C NMR (176MHz, CDCl3) δ140.20, 137.85, 133.56, 133.24, 130.75, 130.19 (q, J = 33.4Hz), 129.09,128.70,127.87,127.39(q,J=3.5Hz),125.14,124.96(q,J=3.5Hz),123.88(q,J=272.8Hz),42.23.HR-ESIMS(m / z):[MH]+calcd.for C 14 H9Br2F3,390.8950; found: 390.8967.

[0045] (3) Synthesis of compound 1c

[0046] Compound 1b (3.94 g, 10.0 mmol) was placed in a 100 mL reaction flask, and the system was evacuated three times under a nitrogen atmosphere. 50 mL of dry tetrahydrofuran was then added. The flask was placed in a cryostat at -78 °C, and then n-butyllithium (1.6 M; 13.1 mL, 21.0 mmol) was slowly added dropwise to the reaction system. The reaction mixture was stirred at -78 °C for 1.5 hours. A solution of dimethyl stannous chloride (2.17 g, 10.0 mmol) in diethyl ether (5 mL) was added dropwise using a syringe. After the addition was complete, the mixture was slowly brought to room temperature and stirred overnight. The reaction was quenched with saturated ammonium chloride solution. The aqueous phase was extracted three times with ethyl acetate. The combined organic phases were washed with saturated NaCl solution and dried over anhydrous Na₂SO₄. After removing the solvent by rotary evaporation, the mixture was purified by C18 reversed-phase column chromatography with acetonitrile as the eluent, yielding 2.68 g of a yellow liquid 1c, in 70% yield.

[0047] 1 H NMR(700MHz, CDCl3) δ7.68(d,J=7.0Hz,1H),7.59-7.57(m,2H),7.46(d,J=7.0Hz,1H),7. 39(d,J=7.0Hz,1H),7.29(t,J=7.0Hz,1H),7.26-7.23(m,1H),4.04(s,2H),0.59(s,6H). 13 C NMR (176MHz, CDCl3) δ147.64,146.64,146.11,140.23,136.23,136.18,130.82 (q,J=33.4Hz),129.14,128.50,126.37,125.21,124.35(q,J=3.5Hz),123.67,122.32(q,J=3.5Hz),46.39,-10.22.HR-ESIMS(m / z):[M+H] + calcd.for C 16 H 15 F3Sn,385.0221; found: 385.0211.

[0048] (4) Compounds F MesB- F Synthesis of A

[0049] Compound 1c (1.6 g, 4.20 mmol) was placed in a 100 mL Schlenk flask, and the system was evacuated three times with nitrogen gas. Then, 30 mL of anhydrous dichloromethane was added under a nitrogen atmosphere. The reaction flask was placed in a cryostat at -78 °C, and boron trichloride (1.0 M; 5.5 mL, 5.50 mmol) was added dropwise to the reaction system. After the addition was complete, the mixture was slowly brought to room temperature and stirred overnight. The next day, the solvent was removed from the reaction system using a vacuum pump. The reaction flask was then placed in an oil bath at 60 °C, and residual Me₂SnCl₂ was removed under dynamic vacuum, leaving a gray solid 1d (1.0 g, 85%). This sample was sensitive to moisture and oxygen, and therefore was used directly in subsequent reactions without further purification. Adding... F Mes (1.52 g, 5.40 mmol), nitrogen was purged three times on a vacuum line, and 60 mL of anhydrous diethyl ether was added. The reaction flask was placed in a cryostat at -78 °C, and then n-butyllithium (1.6 M; 3.7 mL, 5.94 mmol) was slowly added dropwise to the reaction system. After the addition was complete, the mixture was stirred at -78 °C for 0.5 hours, and then heated to room temperature and stirred for 4 hours. The diethyl ether in the reaction system was removed using a vacuum pump to obtain a yellow solid ( F (Mes lithium salt) was added to the reaction flask, followed by the addition of 20 mL of anhydrous toluene and the flask was placed at -78°C. Then, a toluene solution of compound 3d was added, and the mixture was allowed to rise to room temperature and stirred overnight. The next day, 30 mL of water was added to quench the reaction. The aqueous phase was extracted three times with dichloromethane, and the organic phase was washed with saturated NaCl solution and dried over anhydrous Na₂SO₄. The solvent was removed by rotary evaporation, and the concentrated crude product was purified by column chromatography using petroleum ether as the eluent, yielding 0.87 g of a white solid. F MesB- F A, with a yield of 46%.

[0050] 1 H NMR (400MHz, CD2Cl2) δ8.27(s,2H),7.88(s,1H),7.69-7.64(m,2H),7.55(d,J=8.0Hz,1H),7.47(d,J=8.0Hz,1H),7.38-7.31(m,2H),4.67(s,2H). 13C NMR(176MHz,CD2Cl2)δ148.24,147.73,144.82(br,BC),138.52(br,BC),137.75,137.71,135.02(br,BC), 134.63(q,J=33.4Hz),134.25,134.24(q,J=33.4Hz),132.18(q,J=35.2Hz),128.65,126. 77,126.69,126.59,125.31(q,J=3.5Hz),124.08(q,J=274.6Hz),123.39(q,J=272.8Hz), 122.90(q,J=272.8Hz),122.68,122.66,122.64,38.62. 11 B NMR(225MHz,CD2Cl2)δ60.0. HR-ESIMS(m / z):[MH] - calcd.for C 23 H 11 BF 12 ,525.0678; found:525.0691.

[0051] (5) Compounds F MesB- F AQ Synthesis

[0052] compound F MesB- F A (0.87 g, 1.65 mmol) and chromium trioxide (0.43 g, 4.29 mmol) were placed in a round-bottom flask, and 40 mL of acetic acid was added. The reaction mixture was then placed in an oil bath at 120 °C and heated under reflux for 12 hours. After cooling to room temperature, 50 mL of water was added, and the mixture was extracted three times with dichloromethane. The combined organic phases were washed three times with saturated NaHCO3 solution and dried over anhydrous Na2SO4. The solvent was removed by rotary evaporation, and the crude product was purified by column chromatography using petroleum ether:dichloromethane as the eluent, yielding 0.64 g of a pale yellow solid. F MesB- F AQ yield is 72%.

[0053] 1 H NMR (400MHz, CD2Cl2) δ8.66(s,1H),8.44(d,J=8.0Hz,1H),8.30(s,2H),7.83(t,J =8.0Hz,2H),7.65(t,J=8.0Hz,1H),7.43(d,J=8.0Hz,1H),7.32(d,J=8.0Hz,1H). 13C NMR(176MHz,CD2Cl2)δ186.51,142.18(br,BC),140.19(br,BC),139.22,138.41,137.69, 137.49,136.93(br,BC),136.13(q,J=33.4),134.66(q,J=33.4),134.06,133.03(q,J=35.2), 129.75,129.72,128.82,128.55,126.98,125.33(q,J=3.5),124.03(q,J=274.6),123.93(q,J= 272.8),123.19(q,J=272.8). 11 B NMR(225MHz,CD2Cl2)δ60.7.HR-ESIMS(m / z):[M+H] + calcd.for C 23 H9BF 12 O,541.0628; found:541.0625.

[0054] Preparation Example 2

[0055] The compound in which intermediate B″ has R1 and R2 as CF3, R3 and R4 as H, and ring A2 as a benzene ring is named F The preparation method for Mes-TQ is as follows:

[0056]

[0057] (1) Synthesis of compound 2a

[0058] 2,3-Dibromonaphthalene (2.86 g, 10.0 mmol) was placed in a 250 mL reaction flask, and the system was evacuated three times under a nitrogen atmosphere. 70 mL of dry tetrahydrofuran was then added. The flask was placed in a cryostat at -15 °C, and then isopropyl magnesium chloride lithium chloride (1.3 M in THF, 8.46 mL, 11.0 mmol) was slowly added dropwise. The reaction mixture was stirred at -15 °C for 2 hours. The flask was then placed at -78 °C, and ethyl formate (0.41 mL, 5.05 mmol) was slowly added dropwise using a syringe. After the addition was complete, the mixture was slowly brought to room temperature and stirred overnight. The reaction was quenched with 6 M HCl until the aqueous layer showed litmus red. 50 mL of water was then added, and the aqueous phase was extracted three times with ethyl acetate. The combined organic phases were washed with saturated NaCl solution and dried over anhydrous Na₂SO₄. The solvent was removed by rotary evaporation, and the crude product was purified by column chromatography using petroleum ether:ethyl acetate = 10:1 as the eluent to give 3.0 g of white solid 2a, with a yield of 68%.

[0059] 1 H NMR (400MHz, CDCl3) δ8.13(s,2H),7.81(s,2H),7.77(t,J=8.0Hz,4H),7.54-7.47(m,4H),6.69(s,1H),2.75(s,1H). 13 C NMR (101MHz, CDCl3) δ138.47,134.08,132.30,131.88,128.41,128.13,127.25,126.79,126.73,121.57,74.50.

[0060] (2) Synthesis of compound 2b

[0061] Compound 2a (3.0 g, 7.65 mmol) was placed in a round-bottom flask, and 60 mL of acetic acid was added as a solvent. Then, hydroiodic acid (4.0 mL, 57% in H₂O, 30.6 mmol) was added. The reaction apparatus was wrapped with aluminum foil, and the reaction system was placed in an oil bath at 120 °C and heated under reflux for 2 hours. After cooling to room temperature, a saturated sodium sulfite solution was added to quench the reaction, and the reaction solution changed from black to deep yellow. The mixture was then diluted with 80 mL of water, extracted three times with dichloromethane, and the combined organic phases were cooled to 0 °C. NaOH aqueous solution (1 M) was slowly added until litmus blue was obtained. The organic phase was washed with saturated NaCl solution and dried over anhydrous Na₂SO₄. The solvent was removed by rotary evaporation, and the concentrated liquid was purified by column chromatography using petroleum ether as the eluent to give 1.73 g of white solid 2b, in 60% yield.

[0062] 1 H NMR (400MHz, CDCl3) δ8.14 (s, 1H), 7.77-7.74 (m, 1H), 7.70-7.66 (m, 1H), 7.65 (d, J = 8.0Hz, 1H), 7.49-7. 43(m,2H),7.41(s,1H),7.24(t,J=8.0Hz,1H),7.15(t,J=8.0Hz,1H),7.02(d,J=8.0Hz,1H),4.35(s,2H). 13 C NMR (176MHz, CDCl3) δ139.12,136.35,133.43,133.04,132.56,131.55,130. 95,129.41,128.30,127.70,126.74,126.61,126.53,125.28,123.36,42.47.

[0063] (3) Synthesis of compound 2c

[0064] Compound 2b (1.5 g, 3.98 mmol) was placed in a reaction flask, and the system was evacuated three times under a nitrogen atmosphere. 50 mL of dry tetrahydrofuran was then added. The flask was placed in a cryostat at -78 °C, and then n-butyllithium (1.6 M; 5.3 mL, 8.4 mmol) was slowly added dropwise to the reaction system. The reaction mixture was stirred at -78 °C for 1.5 hours. A tetrahydrofuran solution of dimethyl stannous chloride (0.97 g, 4.4 mmol) was added dropwise using a syringe. After the addition was complete, the mixture was slowly brought to room temperature and stirred overnight. The reaction was quenched with saturated ammonium chloride solution. The aqueous phase was extracted three times with ethyl acetate. The combined organic phases were washed with saturated NaCl solution and dried over anhydrous Na₂SO₄. The solvent was removed by rotary evaporation to obtain a yellow oily substance, which was purified by C18 reversed-phase column chromatography using acetonitrile as the eluent to give a colorless liquid. After storage at 0 °C, the liquid solidified into 1.0 g of white solid 2c, with a yield of 70%.

[0065] 1 H NMR(400MHz, CDCl3)δ8.04(s,1H),7.80(s,1H),7.79-7.76(m,2H),7.58(d,J =8.0Hz,1H),7.45-7.40(m,3H),7.30-7.20(m,2H),4.15(s,2H),0.62(s,6H). 13 C NMR (101MHz, CDCl3) δ147.16,143.29,141.02,139.65,136.35,136.05,133.96,132.02,129.02,128.37, 127.62,127.34,126.20,126.10,125.64,125.51,46.84,-9.94.HR-ESIMS(m / z):[M+H] + calcd. for C 19 H 19 Sn, 367.0530; found: 367.0499.

[0066] (4) Compounds F Synthesis of MesB-T

[0067] Compound 2c (1.0 g, 2.74 mmol) was placed in a 100 mL Schlenk flask, and the system was evacuated three times with nitrogen gas. Then, 30 mL of anhydrous dichloromethane was added under a nitrogen atmosphere. The reaction flask was placed in a cryostat at -78 °C, and boron trichloride (1.0 M; 4.11 mL, 4.11 mmol) was added dropwise to the reaction system. After the addition was complete, the mixture was slowly brought to room temperature and stirred overnight. The next day, the solvent was removed from the reaction system using a vacuum pump. The reaction flask was then placed in an oil bath at 60 °C, and residual Me₂SnCl₂ was removed under dynamic vacuum, leaving a gray solid 2d (0.61 g, 85%). This sample was sensitive to moisture and oxygen, and therefore was used directly in subsequent reactions without further purification. Adding... F Mes (0.98 g, 3.48 mmol), nitrogen was purged three times on a vacuum line, and 60 mL of anhydrous diethyl ether was added. The reaction flask was placed in a cryostat at -78 °C, and then n-butyllithium (1.6 M; 2.4 mL, 3.83 mmol) was slowly added dropwise to the reaction system. After the addition was complete, the mixture was stirred at -78 °C for 0.5 hours, and then heated to room temperature and stirred for 4 hours. The diethyl ether in the reaction system was removed using a vacuum pump to obtain a yellow solid. F To obtain the reaction mixture (Mexicosyl lithium salt), 15 mL of anhydrous toluene was added to the reaction flask and the mixture was placed at -78°C. Then, a toluene solution of compound 2d was added, and the mixture was allowed to rise to room temperature and stirred overnight. The next day, 30 mL of water was added to quench the reaction. The aqueous phase was extracted three times with dichloromethane, and the organic phase was washed with saturated NaCl solution and dried over anhydrous Na₂SO₄. The solvent was removed by rotary evaporation, and the concentrated crude product was purified by column chromatography using petroleum ether as the eluent, yielding 0.53 g of a yellow solid. F MesB-T, with a yield of 45%.

[0068] 1 H NMR (400MHz, CD2Cl2) δ8.30(s,2H),8.04(s,1H),7.92-7.89(m,2H),7.80(d,J=8.0Hz,1H),7.64(d,J=4.0H z,2H),7.59(t,J=8.0Hz,1H),7.45(t,J=8.0Hz,1H),7.36(d,J=8.0Hz,1H),7.32-7.28(m,1H),4.75(s,2H). 13C NMR(101MHz, CD2Cl2)δ148.27,141.93,140.01,137.62,136.38,134.78(q,J=32.3Hz),133.96,131.95,131.91(q, J=34.3Hz),129.52,128.95,128.65,127.59,126.65,126.25,126.24,125.91,124.21(q,J=276.7Hz),123.53(q,J= 272.7Hz),38.34. 11 B NMR(128MHz,CD2Cl2)δ58.7.HR-ESIMS(m / z):[M+H] + calcd.for C 26 H 14 BF9,509.1118; found:509.1042.

[0069] (5) Compounds F MesB-TQ Synthesis

[0070] compound F MesB-T (0.50 g, 0.98 mmol) and chromium trioxide (0.26 g, 2.55 mmol) were placed in a round-bottom flask, and 35 mL of acetic acid was added. The reaction mixture was then placed in an oil bath at 120 °C and heated under reflux for 12 hours. After cooling to room temperature, 50 mL of water was added, and the mixture was extracted three times with dichloromethane. The combined organic phases were washed three times with saturated NaHCO3 solution and dried over anhydrous Na2SO4. The solvent was removed by rotary evaporation, and the crude product was purified by column chromatography using petroleum ether:dichloromethane as the eluent, yielding 0.37 g of a pale yellow solid. F MesB-TQ, with a yield of 72%.

[0071] 1 H NMR (400MHz, CDCl3) δ8.69 (s, 1H), 8.30 (d, J = 8.0Hz, 1H), 8.27 (s, 2H), 8.03 (d, J =8Hz,1H),7.90(s,1H),7.83(d,J=8Hz,1H),7.75-7.68(m,2H),7.63(t,J=8.0Hz,1H),7.57(t,J=8.0Hz,1H),7.43(d,J=8Hz,1H). 13C NMR (101MHz, CDCl3) δ187.74,140.46,139.56,137.03,136.13,135.13,134.90,134.85(q,J=32.3Hz),134.11,1 33.30,132.46(q,J=34.3Hz),130.44,130.40,129.69,129.66,129.05,128.64,126.34,123.72(q,J=276.7Hz), 122.96(q,J=273.7Hz). 11 B NMR(128MHz, CDCl3)δ59.8.HR-ESIMS(m / z):[M+H] + calcd. for C 26 H 12 BF9O,523.0910; found:523.0923.

[0072] Preparation Example 3

[0073] Synthesis of compound NPA-Br (the synthesis of intermediate A follows the same method).

[0074]

[0075] Diphenylamine (0.5 g, 2.95 mmol), 2,3-dibromonaphthalene (1.01 g, 3.55 mmol), sodium tert-butoxide (0.43 g, 4.43 mmol), tris(dibenzylacetone)palladium (0.082 g, 0.09 mmol), and tri-tert-butylphosphine (0.043 g, 0.21 mmol) were placed in a 100 mL reaction flask, and 30 mL of anhydrous toluene was added. The reaction flask was then placed in liquid nitrogen and frozen for 15 minutes, followed by evacuation using an oil pump for 10 minutes to remove air. The system was then thawed, and the above procedure was repeated three times. The reaction flask was then heated in an oil bath at 100 °C for 12 hours. After cooling to room temperature, 20 mL of water was added, and the mixture was extracted three times with dichloromethane. The organic phases were combined and washed three times with saturated NaCl solution, and then dried over anhydrous Na₂SO₄. The solvent was removed by rotary evaporation, and the crude product was purified by column chromatography using petroleum ether:dichloromethane = 8:1 as the eluent to give 0.46 g of white solid, with a yield of 42%.

[0076] 1 H NMR (400MHz, CD2Cl2) δ8.22(s,1H),7.80(t,J=4.0Hz,1H),7.73-7.69(m,2H),7.52-7.46(m,2H),7.24(t,J=8.0Hz,4H),7.02-6.96(m,6H). 13C NMR (176MHz, CD2Cl2) δ147.81,143.35,133.89,133.76,133.10,130.31,129.45,127.69,127.08,127.05,122.82,122.46,122.41.HR-ESIMS(m / z):[M+H] + calcd.for C 22 H 16 BrN,374.0539; found:374.0521.

[0077] Example 1

[0078] Synthesis of compound TPA-s-Mes*B(I-5)

[0079]

[0080] 2-Bromo-triphenylamine (0.33 g, 1.0 mmol) was placed in a 50 mL Schlenk flask, and the system was evacuated three times under a nitrogen atmosphere. 10 mL of anhydrous tetrahydrofuran was added, and the reaction mixture was placed in a cryostat at -78 °C. Then, n-butyllithium (1.6 M; 0.69 mL, 1.1 mmol) was slowly added dropwise, and the reaction mixture was stirred at -78 °C for 1.5 hours. A 5 mL solution of Mes*B-AQ (0.52 g, 1.2 mmol) in tetrahydrofuran was added dropwise using a syringe. After the addition was complete, the mixture was slowly brought to room temperature and stirred overnight. The reaction was quenched with saturated ammonium chloride solution. The aqueous phase was extracted three times with dichloromethane. The combined organic phases were washed with saturated NaCl solution and dried over anhydrous Na₂SO₄. The organic phase was placed in a single-necked flask, and the solvent was removed by rotary evaporation. 20 mL of glacial acetic acid and 1 mL of hydrochloric acid were added, and the mixture was heated under reflux for 6 hours. After cooling to room temperature, 30 mL of water was added, and the mixture was filtered through a Buchner funnel. The residue was purified by column chromatography using petroleum ether and dichloromethane as the eluent, yielding 0.43 g of a white solid with a yield of 65%.

[0081] 1 H NMR (400MHz, CD2Cl2) δ7.78-7.74(m,2H),7.67(dd,J1=7.6Hz,J2=1.6Hz,2H),7.64-7.60(m,1H),7.58(s,2H),7.54(d,J=8.0Hz, 4H),7.42-7.37(m,2H),7.18(t,J=8.0Hz,2H),6.90-6.84(m,2H),6.55-6.50(m,4H),6.35(d,J=8.0Hz,2H),1.45(s,9H),1.27(s, 18H). 13C NMR (176MHz, CD2Cl2) δ158.18,153.10,148.93,141.49,140.16,138.13,137.45, 133.97,132.85,132.63,131.63,131.46,131.25,128.95,127.12,126.13,123.28,120.59,115.36,53.35,38.90,35.51,35.02,31.57. 11 B NMR(225MHz,CD2Cl2)δ62.6.HR-ESIMS(m / z):[M+ H] + calcd.for C 49 H 50 BN, 664.4109; found: 664.4127.

[0082] Example 2

[0083] Synthesis of compound PHX-s-Mes*B(I-6)

[0084]

[0085] The synthesis of compound PHX-s-Mes*B was consistent with that of compound TPA-s-Mes*B, yielding 0.33 g of white solid with a yield of 54%.

[0086] 1 H NMR(400MHz, CD2Cl2)δ7.73-7.07(m,16H),6.76(t,J=8.0Hz,2H),6.63(t,J=8.0Hz, 1H),6.53(d,J=8.0Hz,1H),6.11(d,J=8.0Hz,1H),1.44(s,9H),1.24(s,9H),1.21(s, 9H). 13 C NMR (176MHz, CD2Cl2) δ155.68,154.34,152.97,152.94,149.12,149.05,147.15, 140.98,138.15,137.12,136.75,135.20,134.69,134.05,133.82,133.49,132.38,131.81,131.60, 129.05,127.07,126.61,125.28,124.25,123.51,123.26,123.23,123.12,117.77,116.98,116.44, 114.19,53.19,38.90,35.44,35.03,31.57.11 B NMR(225MHz,CD2Cl2)δ62.1.HR-ESIMS (m / z):[M] + calcd.for C 49 H 48 BNO,677.3829; found:677.3814.

[0087] Example 3

[0088] compound TPA-s- F Synthesis of MesB(I-13)

[0089]

[0090] compound TPA-s- F The synthesis of MesB was consistent with that of compound TPA-s-Mes*B, yielding 0.35 g of a yellow solid in 50% yield.

[0091] 1 H NMR (400MHz, CD2Cl2) δ8.33(s,2H),7.76(t,J=8.0Hz,2H),7.62(t,J=8.0Hz,1H),7.56-7.48(m,6H),7.29(d,J=8.0 Hz,2H),7.21-7.17(m,2H),6.89-6.84(m,2H),6.55(t,J=8.0Hz,2H),6.42(d,J=8.0Hz,2H),6.34(d,J=8.0Hz,2H). 13 C NMR (176MHz, CD2Cl2) δ161.11,145.78,141.44,139.91,136.58,134.89,134.78(q,J=31.9Hz),133.00,131.99(q,J=33.4Hz),1 31.68,131.65,131.43,129.00,128.67,127.20,126.05,124.31(q,J=274.6Hz),123.46(q,J=272.8Hz),120.89,115.53,53.27. 11 B NMR(225MHz,CD2Cl2)δ62.8. HR-ESIMS(m / z):[MH] + calcd.for C 40 H 23 BF9N,700.1853; found:700.1844.

[0092] Example 4

[0093] compound TPA-s- F Synthesis of MesBF(I-17)

[0094]

[0095] compound TPA-s- F The synthesis of MesBF was consistent with that of compound TPA-s-Mes*B, yielding 0.35 g of a yellow solid in 58% yield.

[0096] 1 H NMR (400MHz, CD2Cl2) δ8.35(s,2H),7.86(s,1H),7.77(t,J=8.0Hz,2H),7.63(t,J =8.0Hz,1H),7.59-7.53(m,4H),7.42(s,2H),7.33(d,J=8.0Hz,1H),7.23(t ,J=8.0Hz,1H),6.93-6.88(m,2H),6.58(t,J=8.0Hz,2H),6.41-6.38(m,4H). 13 C NMR(176MHz,CD2Cl2)δ161.16,160.95,144.74,141.17,140.02,137.03, 136.91,135.72,135.55,135.35,134.81(q,J=31.7Hz),133.06,132.39(q ,J=35.2Hz),131.72,131.55,131.21,129.08(q,J=3.52Hz),127.88,127 .63,126.84,126.41,125.70,124.26(q,J=274.6Hz),124.15,124.14(q,J =272.8Hz),122.60,122.55,122.54,122.52,121.12,115.78,54.24. 11 B NMR(225MHz, CD2Cl2)δ59.3.HR-ESIMS(m / z):[M+H] + calcd.for C 41 H 22 BF 12 N, 768.1726; found: 768.1705.

[0097] Example 5

[0098] Compound PHX-s- F Synthesis of MesBF(I-18)

[0099]

[0100] Compound PHX-s- F The synthesis of MesBF was consistent with that of compound TPA-s-Mes*B, yielding 0.64 g of a yellow solid in 68% yield.

[0101] 1 H NMR (400MHz, CD2Cl2) δ8.34 (s, 2H), 7.75 (d, J = 8.0Hz, 1H), 7.58-7.07 (m, 12H), 6.8 1-6.79(m,2H),6.68(t,J=4.0Hz,1H),6.45(d,J=4.0Hz,1H),6.05(d,J=4.0Hz,1H). 13 C NMR (176MHz, CD2Cl2) δ158.08,149.17,147.31,144.46,137.61,135.07,134.76(q,J=31.7 Hz),133.87,132.46(q,J=35.2Hz),131.49,131.43,129.24,127.57,126.91,126.85,126.5 7,126.25,125.01,124.89,124.70,124.49,124.35(q,J=272.8Hz),124.30,124.21(q,J=27 4.6Hz),124.05,123.60,123.45,123.15,123.05,121.59,117.90,117.48,116.34,114.77, 53.47. 11 B NMR(225MHz,CD2Cl2)δ60.5.HR-ESIMS(m / z):[M] + calcd.forC 41 H 20 BF 12 NO, 781.1446; found:781.1452.

[0102] Example 6

[0103] Compound NPA-s- F Synthesis of MesBF(II-1)

[0104]

[0105] Compound NPA-s- FThe synthesis of MesBF was consistent with that of compound TPA-s-Mes*B, yielding 0.23 g of yellow solid in 56% yield.

[0106] 1 H NMR (400MHz, CDCl3) δ8.34(s,1H),8.32(s,1H),7.84-7.79(m,3H),7.67(t,J=8.0Hz,1H),7.59(d,J=8.0Hz,2H),7.52(d,J=8.0H z,1H),7.47(t,J=8.0Hz,1H),7.39(t,J=8.0Hz,2H),7.36-7.27(m,3H),7.21(t,J=8.0Hz,2H),7.08(t,J=8.0Hz,1H),6.97-6.93 (m,2H),6.63(t,J=8.0Hz,2H),6.49(d,J=8.0Hz,1H),6.42(d,J=8.0Hz,1H). 13 CNMR (176MHz, CDCl3) δ160.68,160.51,144.65,141.01,139.90,138.35,136.75,136.54,135.63, 135.42,134.67(q,J=31.7Hz),133.90,133.03,133.00,132.28(q,J=33.4Hz),131.65,131.28,13 1.17,130.38,128.99,128.79,128.39,128.37,127.84,127.58,127.47,126.48,126.42,126.22, 125.31,124.68,123.98(q,J=274.6Hz),123.76,123.70(q,J=272.8Hz), 123.41,123.12,122.43,122.41,122.21,121.03,115.35,110.47,53.63. 11 B NMR(225MHz, CDCl3)δ60.6. HR-ESIMS(m / z):[M] + calcd.for C 45 H 24 BF 12 N, 817.1810; found: 817.1830.

[0107] Example 7

[0108] Compound NPA-s- F Synthesis of MesBT(II-2)

[0109]

[0110] Compound NPA-s- F The synthesis of MesBT was consistent with that of compound TPA-s-Mes*B, yielding 0.41 g of a yellow solid with a yield of 51%.

[0111] 1 H NMR(400MHz,CD2Cl2)δ8.42(s,1H),8.40(s,1H),7.94(s,1H),7.90(s,1H),7.86(t, J=8.0Hz,2H),7.78(d,J=8.0Hz,1H),7.71(t,J=8.0Hz,3H),7.64(d,J=8.0Hz,1H),7.54(d,J=8.0Hz,1H),7.50-7.42(m,2H),7.40- 7.34(m,3H),7.21-7.14(m,3H),7.02-6.99(m,2H),6.91(t,J=8.0Hz,1H),6.68(s,1H),6.60-6.54(m,2H),6.43(d,J=12.0Hz,1H). 13 CNMR(176MHz,CD2Cl2)δ160.87,156.54,145.78,141.56,139.90,139.85,138.62,137.27,136.83,135.29,135.06(q,J=31.7Hz),134.98(q,J= 33.4Hz),133.13,133.06,132.88,132.41,132.21,132.02,131.89,131 .82,131.67,131.57,130.39,129.42,129.19,129.00,128.00,127.42, 127.19,126.51,126.42,126.41,126.17,125.18,124.48(q,J=274.6Hz) ,123.61,123.54(q,J=272.8Hz),123.44,120.90,115.45,110.28,53.29. 11 B NMR(225MHz,CD2Cl2)δ61.4. HR-ESIMS(m / z):[M+H] + calcd.for C 48 H 27 BF9N,800.2166; found:800.2161.

[0112] Example 8

[0113] Compound PHX-s- F Synthesis of MesBT(II-3)

[0114]

[0115] Compound PHX-s- F The synthesis of MesBT was consistent with that of compound TPA-s-Mes*B, yielding 0.37 g of a yellow solid in 49% yield.

[0116] 1 H NMR(400MHz,CD2Cl2)δ8.37(s,2H),7.88(s,1H),7.78-7.67(m,4H),7.44-7.32(m,6H),7.23-7.1 0(m,5H),6.78-6.75(m,2H),6.64(t,J=8.0Hz,1H),6.54(d,J=8.0Hz,1H),6.12(d,J=8.0Hz,1H). 13 C NMR (176MHz, CD2Cl2) δ157.95,149.34,147.16,145.52,137.08,135.94,134.95(q,J=31.7Hz),133.91,132.14(q,J=33. 4Hz),132.13,131.67,129.29,129.02,128.96,128.03,126.96,126.78,126.62,125.44,125.11,124.32(q,J=274.6Hz), 124.29,123.82,123.53,123.50(q,J=272.8Hz),123.46,121.97,117.92,117.35,116.20, 114.15,52.94. 11 B NMR(225MHz,CD2Cl2)δ60.9.HR-ESIMS(m / z):[M] + calcd.for C 44 H 23 BF9NO,764.1802; found:764.1786.

[0117] For convenience, the nitrogen-boron dual-doped spirocyclic compounds prepared in the above preparation examples are named TPA-s-Mes*B, compound (I-6) is named PHX-s-Mes*B, and compound (I-13) is named TPA-s- FMesB, compound (I-17) is named TPA-s- F MesBF, compound (I-18) is named PHX-s- F MesBF, compound (II-1) was named NPA-s- F MesBF, compound (II-2) was named NPA-s- F MesBT, compound (II-3) is named PHX-s- F MesBT.

[0118] Application examples

[0119] The nitrogen-boron dual-doped spirocyclic dual-small-molecule luminescent material of this embodiment will be tested below.

[0120] (1) Photophysical property analysis

[0121] The UV-Vis absorption spectra of the above nitrogen-boron dual-doped spirocyclic compounds (solvent dichloromethane) were tested, as follows: Figure 1 As shown in (a), the strong absorption band in the 230-310 nm range indicates the presence of n-π* and π-π* transition absorptions within the molecule, while the weak absorption band in the 310-370 nm range is attributed to charge transfer absorption from arylamine to triarylboron, indicating strong electronic coupling between the donor and acceptor in the ground-state electronic structure. This interaction through the spirocyclic carbon atom in spirocyclic compounds can be attributed to the homoconjugation effect. Compared to other compounds, compound NPA-s- F MesBF, NPA-s- F MesBT and PHX-s F MesBTs have extended π-conjugation, which leads to a significant redshift in their charge transfer absorption band.

[0122] The fluorescence emission spectra of nitrogen-boron dual-doped spirocyclic compounds (in toluene solvent) were also tested. Figure 1 As shown in (b), compounds TPA-s-Mes*B and TPA-s-, which use triphenylamine as a donor, can be observed. F MesB and TPA-s- F MesBF exhibits emission peaks at 459 nm, 511 nm, and 555 nm, and demonstrates high fluorescence quantum efficiency (82-94%). Compounds containing phenoxazine units, such as PHX-s-Mes*B and PHX-s- F MesBF and PHX-s- F The emission peaks of MesBT were 482 nm, 608 nm, and 534 nm, with fluorescence quantum efficiencies of 33%, 58%, and 6%, respectively. NPA-s- F MesBF and NPA-s-F The emission peaks of MesBT were 567 nm and 535 nm, respectively, with fluorescence quantum efficiencies of only 18% and 2%. The results indicate that compounds containing triphenylamine exhibit stronger luminescence in toluene, while NPA-s- F MesBF, NPA-s- F MesBT and PHX-s- F Molecules with extended π systems, such as MesBT, exhibit weaker luminescence in toluene. Compared to TPA-s-Mes*B, PHX-s- F The emission of MesBF in toluene redshifted by 149 nm. This is due to the stronger electron-donating ability of the phenoxazine-containing donor unit compared to the triphenylamine group, which narrows the molecular band gap.

[0123] To further investigate the luminescence behavior of these compounds, we tested the emission spectra of the nitrogen-boron dual-doped spirocyclic compounds in different solvents. For example... Figure 2 As shown, where Figure 2 (a) shows the emission spectrum and fluorescence image of compound TPA-s-Mes*B. Figure 2 (b) shows the emission spectrum and fluorescence image of compound PHX-s-Mes*B. Figure 2 (c) is the compound TPA-s- F Emission spectrum and fluorescence images of MesB Figure 2 (d) is the compound TPA-s- F Emission spectrum and fluorescence images of MesBF, Figure 2 (e) is the compound PHX-s- F The emission spectra and fluorescence images of MesBF show that the emission spectra of nitrogen-boron dual-doped spirocyclic compounds are dependent on solvent polarity. With increasing solvent polarity, the emission peaks of these compounds gradually red-shift and broaden. Taking TPA-s-Mes*B as an example, its emission peak in n-hexane is located at 426 nm, and in N,N-dimethylformamide at 519 nm, with a red-shift of 93 nm accompanied by a change in emission color from blue to green. This indicates that BN-doped spirocyclic compounds possess intramolecular charge transfer characteristics, exhibiting a large transition dipole moment from the ground state to the excited state.

[0124] (2) Electrochemical property analysis

[0125] To investigate the relative energy levels of nitrogen-boron co-doped spirocyclic compounds, cyclic voltammetry was used for electrochemical testing. Figure 3The table shows the cyclic voltammetry curves of nitrogen-boron dual-doped spirocyclic compounds. It can be seen that these compounds all exhibit reversible redox peaks, indicating good electrochemical stability. The HOMO / LUMO energy levels of these compounds can be estimated based on the redox initiation potentials, and the calculation results are shown in Table 1. In the Mes*-substituted compounds, the same acceptor unit makes their LUMO energy levels very close. Since the electron-donating ability of the phenoxazine unit is stronger than that of triphenylamine, PHX-s-Mes*B is more easily oxidized than TPA-s-Mes*B. For compounds TPA-s-Mes*B and TPA-s- F MesB and TPA-s- F MesBF, the three compounds share the same triphenylamine donor unit, resulting in similar HOMO energy levels, while for the LUMO energy level, due to TPA-s- F MesBF contains stronger electron-withdrawing groups, TPA-s- F MesBF exhibits a lower LUMO energy level. PHX-s-Mes*B, PHX-s- F MesBF and PHX-s- F MesBTs exhibit similar HOMO levels due to the same donor unit, PHX-s- F MesBF is more easily reduced due to its stronger electron-withdrawing groups. NPA-s- F MesBF and NPA-s- F MesBT exhibits similar HOMO and LUMO energy levels. The results are shown in Table 1 below:

[0126] Table 1. Photophysical and electrochemical data of nitrogen-boron co-doped spirocyclic compounds

[0127]

[0128] Note: a. In dichloromethane (1.0 × 10⁻⁶) -5 M -1 a. Absorption peak, b. Emission peak and absolute fluorescence quantum efficiency in toluene under nitrogen, c. Half-wave potential of oxidation / reduction peak, dE LUMO / E HOMO =-(4.8+E) red / E ox )

[0129] (3) Analysis of thermally activated delayed fluorescence properties

[0130] The transient fluorescence decay curves of the nitrogen-boron dual-doped spirocyclic compound in different solvents were tested. Figure 4 It is the compound TPA-s-Mes*B, PHX-s-Mes*B, TPA-s-F MesB, TPA-s- F MesBF and PHX-s- F The transient fluorescence decay curves of MesBF in different solvents are shown in the left figure, which was tested under anaerobic conditions, and the right figure was tested under aerobic conditions. Figure 4 (a) is the transient fluorescence spectrum of TPA-s-Mes*B in different solvents; Figure 4 (b) shows the transient fluorescence spectra of PHX-s-Mes*B in different solvents; Figure 4 (c) is TPA-s- F Transient fluorescence spectra of MesB in different solvents; Figure 4 (d) is TPA-s- F Transient fluorescence spectra of MesBF in different solvents; Figure 4 (e) is PHX-s- F The transient fluorescence spectra of MesB in different solvents show that these compounds all exhibit a double exponential decay process under anaerobic conditions, including transient fluorescence on the nanosecond timescale and delayed fluorescence on the microsecond timescale, indicating that they conform to the thermally activated delayed fluorescence (TADF) characteristic in dilute solutions. When the solutions of these compounds are exposed to air, subsequent transient spectroscopy tests reveal no significant delayed component, indicating that the excited triplet states generated by these compounds are quenched by oxygen.

[0131] To further investigate the TADF properties of nitrogen-boron co-doped spirocyclic compounds, the photophysical properties in the doped thin films were tested. Thin films of nitrogen-boron co-doped spirocyclic compounds were prepared by spin-coating with 5 wt% doping in the host material. TPA-s-Mes*B and PHX-s-Mes*B were doped in di[2-((oxo)diphenylphosphino)phenyl]ether (DPEPO). F MesB, TPA-s- F MesBF and PHX-s- F MesBF is doped in 4,4'-bis(9-carbazole)biphenyl (CBP). Figure 5 The emission spectrum and transient fluorescence decay curves of a 5 wt% doped film of a boron-nitrogen dual-doped spirocyclic compound are shown. Figure 5 (a) is a 5wt% doped film of boron and nitrogen dual-doped spirocyclic compounds (TPA-s-Mes*B, PHX-s-Mes*B doped in DPEPO, TPA-s- F MesB, TPA-s- F MesBF and PHX-s- FEmission spectra of MesBF doped in CBP. The Mes*-substituted compounds TPA-s-Mes*B and PHX-s-Mes*B exhibit deep blue and blue luminescence in the doped film, with fluorescence quantum efficiencies of 65% and 56%, respectively. F Mes-substituted compounds TPA-s- F MesB, TPA-s- F MesBF exhibits green and yellowish-green light in the doped film, with emission peaks at 508 nm and 538 nm, respectively. Although the two molecules share the same main framework, TPA-s- F MesBF has an additional electron-withdrawing substituent CF3 on its boronanthracene ring, resulting in a 30 nm redshift in its emission spectrum in the doped film. Both compounds exhibit a fluorescence quantum efficiency of up to 100% in the doped film. PHX-s- F MesBF exhibits yellow light in the doped film, with an emission peak at 562 nm and a fluorescence quantum efficiency of 97%. Notably, the emission peak in the doped film shows a blue shift compared to that in toluene solution. This may be related to the restriction of molecular structure recombination and relaxation under excited-state conditions by the surrounding solid medium, as well as the reduced intermolecular interactions within the doped film. Similarly, pure films of nitrogen-boron co-doped spirocyclic compounds were prepared using spin-coating. Figure 5(c) shows the emission spectra of the pure nitrogen-boron co-doped spirocyclic compound films, including the triphenylamine-containing compounds TPA-s-Mes*B and TPA-s- F MesB and TPA-s- F The emission peaks of MesBF in the thin film are located at 451 nm, 496 nm, and 536 nm, respectively, showing a blue shift compared to the corresponding doped film. Its fluorescence quantum efficiency is 22-58%, significantly lower than that of the doped film, indicating that the nitrogen-boron dual-doped spirocyclic compound achieves effective energy transfer in the host material. The transient fluorescence decay curves of the nitrogen-boron dual-doped spirocyclic molecule thin film under a nitrogen atmosphere were further tested at room temperature (Figures 5(b) and 5(d)). Table 2 shows the photophysical data of the nitrogen-boron dual-doped spirocyclic compound in the thin film. The transient fluorescence decay curves in both the doped and pure films exhibit two distinct components: a nanosecond-level transient decay and a microsecond-level delayed decay, indicating that the nitrogen-boron dual-doped spirocyclic molecule in the thin film conforms to the TADF characteristic.

[0132] We further tested the temperature-dependent transient fluorescence decay curves of the nitrogen-boron co-doped spirocyclic compound in the doped film. Figure 6(ae) shows the temperature-dependent transient fluorescence decay curves of the nitrogen-boron co-doped spirocyclic compound in the doped film. As the temperature increases, the proportion of delayed fluorescence gradually increases, indicating that the delayed fluorescence is generated through the anti-gap crossover process. Figure 6(fj) is the k of the nitrogen-boron dual-doped spirocyclic compound in the doped film. RISC The graph shows the relationship between temperature and thermal activation energy ΔE reported by Adachi et al. ST The calculation method for k RISC With ΔE ST The relationship is: k RISC ∝Aexp(-ΔE ST / kBT), where A is the frequency factor, and kB and T are the Boltzmann constant and temperature, respectively. Based on photophysical data in the doped film, and following the method of Adachi et al., the ΔE of these molecules was calculated using the Arrhenius expression. ST ΔE of boron-nitrogen heterocyclic molecules in doped films ST The luminescence values ​​ranged from 28.5 to 75.5 meV, all consistent with the luminescence characteristics of TADF materials.

[0133] Table 2 Photophysical data of boron-nitrogen heterospirocyclic compounds in thin films

[0134]

[0135] (4) Thermal property analysis

[0136] Thermogravimetric analysis was performed on these compounds under a nitrogen atmosphere, such as... Figure 7 As shown, the thermal decomposition temperatures of the nitrogen-boron dual-doped spirocyclic compounds are all above 275.4 °C. Among compounds containing boron anthracene units, Mes*-substituted compounds are more... F Mes-substituted compounds exhibit higher thermal decomposition temperatures. Furthermore, in F Among the Mes-substituted compounds, the boron-containing heterocyclic tetraphenyl compounds exhibit higher thermal decomposition temperatures compared to boron-containing anthracene compounds. These results indicate that nitrogen-boron dual-doped spirocyclic compounds all possess good thermal stability, which is beneficial for maintaining the stability of the compounds during the fabrication of optoelectronic devices.

[0137] (5) Photoelectric performance analysis

[0138] Given the TADF characteristics and good thermal stability of nitrogen-boron dual-doped spirocyclic compounds, we used triphenylamine as a donor in the molecule (TPA-s-Mes*B, TPA-s- F MesB and TPA-s- FAn electroluminescent device was fabricated using a solution method with MesBF as the emitting layer. The device structure is as follows: ITO / PEDOT:PSS (30nm) / mCP:emission layer (50nm) / TSPO1 (20nm) / TmPyPB (20nm) / LiF (1nm) / Al (100nm), where ITO and Al are the anode and cathode, respectively; PEDOT:PSS (polyethylenedioxythiophene-poly(styrene sulfonate)) serves as the hole injection layer and hole transport layer; mCP (1,3-dicarbazole-9-ylbenzene) is the host material; TSPO1 (diphenyl[4-(triphenylsilyl)phenyl]oxyphosphine) is the hole blocking layer; and TmPyPB (1,3,5-tris(3-pyridyl-3-phenyl)benzene) and LiF (lithium fluoride) are the electron transport layer and electron injection layer, respectively. Device fabrication: First, the ITO glass substrate was ultrasonically cleaned sequentially with detergent, deionized water, acetone, and isopropanol for 10 minutes, and then baked in an oven at 120°C for 5 minutes. Before spin-coating the PEDOT:PSS film, it was treated with plasma for 20 minutes, and then the PEDOT:PSS solution was spin-coated onto the ITO glass substrate at 1800 rpm and annealed at 120°C for 10 minutes. The substrate containing PEDOT:PSS was then transferred into a nitrogen-filled glove box. The luminescent material (30 wt% doped with mCP) was dissolved in chlorobenzene and spin-coated onto the PEDOT:PSS at 2000 rpm, annealed at 50°C for 10 minutes, and then placed in a vacuum deposition chamber. At 5 × 10⁻⁶... -4 Under pressure of Pa, an organic layer and a metal cathode are deposited sequentially, and the organic material is then... rate, LiF with Metallic aluminum Evaporation was performed at a specific rate. Device testing: The JVL profile of the device was measured using a Keithley 2400 source meter in a glove box. The effective area of ​​the fabricated device was 10 mm². 2 None of the devices were packaged. The electroluminescence (EL) spectra of the devices were recorded using an optical analyzer PR-745. The external quantum efficiency of the devices was calculated using the driving current and the corresponding device brightness and electroluminescence spectrum (assuming the devices were Lambertian light sources).

[0139] Figure 8 It includes the electroluminescence spectrum, corresponding device photographs, and CIE color codes. Figure 9 It is a current density-voltage-brightness curve. Figure 10 It is the brightness-external quantum efficiency curve. Figure 11 The data for the electroluminescent devices, shown in Table 3, are the brightness-current efficiency curves. Figure 8 It can be seen that TPA-s-Mes*B, TPA-s- FMesB and TPA-s- F The emission peaks of MesBF were 454 nm, 502 nm, and 536 nm, which are very similar to the photoluminescence spectra of the corresponding compounds in the doped films. TPA-s-Mes*B,TPA-s- F MesB and TPA-s- F The turn-on voltages of MesBF are 2.6V, 2.2V and 3.0V, respectively, indicating that devices based on these materials have low turn-on voltages.

[0140] Table 3. Device-related data based on nitrogen-boron dual-doped spirocyclic compounds

[0141]

[0142] Where: a) turn-on voltage; b) maximum luminance; c) maximum current efficiency; d) maximum power efficiency; e) maximum external quantum efficiency; f) 100 cd m -2 CIE at that time.

[0143] Device performance tests show that, based on TPA-s- F The maximum luminance of MesBF devices is 4797 cd m. -2 The maximum current efficiency is 77.38 cd A. -1 The maximum power efficiency is 490.69 lm W. -1 The maximum external quantum efficiency is 22%, placing this device performance among the top reported solution-fabricated TADF-based devices with spirocyclic structures. These results demonstrate that enhancing the electron-withdrawing ability of the acceptor unit in nitrogen-boron dual-doped spirocyclic compounds can improve device performance.

Claims

1. A nitrogen and boron double-doped spiro compound, characterized in that, The structure of the TPA-s-FMesBF is as follows: 。 2. The method for preparing the nitrogen-boron dual-doped spirocyclic compound according to claim 1, characterized in that, The synthesis route is as follows: 。 3. An organic electroluminescent device, characterized by comprising The organic functional layer includes the boron and nitrogen double-doped spiro compound TPA-s-FMesBF according to claim 1.

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