A boron-oxygen-based organic light-emitting macrocyclic compound and its preparation method

Abstract

This invention discloses an organic light-emitting macrocyclic material based on a boron-oxygen structure, relating to the field of organic optoelectronic materials technology, with the structural formula: [Formula omitted]. Wherein, n represents the number of repeating units, with a value ranging from 3 to 4, and the Donor group is selected from one of the following groups: [List of groups omitted]. This invention also discloses an organic light-emitting macrocyclic material based on a boron-oxygen multiple resonance thermally activated delayed fluorescence framework covalently linked to 9,10-dihydro-9,9-dimethylacridinium, phenthiazine, and phenoloxazine groups, cyclized via Buchwald-Hartwig coupling and Friedel-Crafts alkylation. This invention modulates the luminescence performance of the material by selecting the MR-TADF framework and donor units in a modular manner, constructing macrocyclic homologues with different cavity sizes. This material exhibits advantages such as high fluorescence quantum yield, resistance to aggregation quenching, and high color purity, significantly improving the efficiency and stability of organic electroluminescent devices.

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronic materials technology, specifically to a boron-oxygen-based organic light-emitting macrocyclic compound and its preparation method. Background Technology

[0002] Organic light-emitting diodes (OLEDs), as a new generation of display and lighting technology, have achieved leapfrog development from basic science to industrial revolution over the past four decades due to their advantages such as thinness, flexibility, and high contrast, demonstrating broad application prospects. The luminescent material is the core of OLEDs, and its performance directly determines the efficiency of the light-emitting device. In recent years, third-generation thermally activated delayed fluorescence (TADF) materials have achieved 100% exciton utilization by using triplet exciton anti-intersystem crossing to the singlet state and radiating light, greatly improving the external quantum efficiency of OLED devices. To meet the stringent requirements of color saturation for next-generation ultra-high-definition displays, in 2016, the Adachi team at Kyushu University in Japan reported multiple resonance thermally activated delayed fluorescence (MR-TADF) materials. This material inherits the theoretical exciton utilization of TADF materials while exhibiting high color purity and external quantum efficiency. Subsequently, MR-TADF materials based on boron nitrogen, boron oxygen, and nitrogen carbonyl groups have been reported. The boron oxygen core has the lowest molecular weight and the smallest overall molecular skeleton among multiple resonance cores. However, it has abundant functionalization sites, a wide range of modifiers, and tunable material structure.

[0003] From an application perspective, MR-TADFs are typically composed of rigid planar π-conjugated frameworks, which are prone to aggregation in the aggregated state, leading to fluorescence quenching and reduced solid-state efficiency. Macrocyclic molecules, with their three-dimensional structure, are advantageous in maintaining molecular rigidity, locking conformation, suppressing structural relaxation and nonradiative transitions, improving color purity and radiative transition rates, and simultaneously hindering close intermolecular packing, thus suppressing fluorescence quenching caused by aggregation. They hold great potential for application in the OLED field. Currently, there are few reports on macrocyclic compounds based on MR-TADFs. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing an organic light-emitting macrocyclic material based on a boron-oxygen structure, with the following structural formula:

[0005]

[0006] Where n represents The number of repeating units, n, takes the value of 3 or 4, and the Donor group is selected from one of the following groups:

[0007] .

[0008] A method for preparing an organic light-emitting macrocyclic material based on a boron-oxygen structure includes:

[0009] Step 1: 2,5-Dibromo-1,3-difluorobenzene, p-tert-butylphenol and potassium carbonate were added to N-methylpyrrolidone, reacted under a protective gas and then purified to obtain compound I;

[0010] Step 2: Under a protective gas atmosphere, n-butyllithium was added to a toluene solution of compound I, followed by the addition of boron tribromide and N,N-diisopropylethylamine. After reaction and purification, compound II was obtained.

[0011] Step 3: Compound II and the donor raw material are added to an organic solvent. The donor raw material is 9,10-dihydro-9,9-dimethylacrimidine, phenthiazide, or phenoloxazine. A base is added, and under a protective gas, a palladium catalyst and a phosphine ligand are added. After the reaction, the mixture is purified to obtain compound III.

[0012] Step 4: Compound III is added to an organic solvent, and under a protective gas atmosphere, paraformaldehyde and an acid catalyst are added. After reaction and purification, an organic light-emitting macrocyclic material based on a boron-oxygen structure is obtained.

[0013] Furthermore, the organic solvent in step 3 is one of toluene, o-xylene, and m-xylene.

[0014] Furthermore, the alkali in step 3 is one of Na2CO3, K2CO3, KOH, t-BuONa, and NaOH.

[0015] Furthermore, the palladium catalyst in step 3 is Pd(OAc)2 or PdCl2 or Pd2(dba)3 or Pd(PPh2)Cl2 or Pd(dppf)Cl2.

[0016] Further, the phosphine ligand in step 3 is 2-di-tert-butylphosphine-2',4',6'-triisopropyl-3,6-dimethoxy-1,1'-biphenyl, tri-tert-butylphosphine, PPh3, P( t One of Bu)3·BF4 and 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl.

[0017] Furthermore, the solvent in step 4 includes one of dichloromethane, chloroform, and 1,2-dichloroethane.

[0018] Furthermore, the catalyst in step 4 is one of boron trifluoride diethyl ether, FeCl3·6H2O, and trifluoroacetic acid.

[0019] Furthermore, in step 1, the reaction temperature is 180°C.

[0020] Furthermore, in step 4, the reaction temperature is room temperature.

[0021] The beneficial effects of this invention are as follows:

[0022] 1. This invention creatively combines the boron-oxygen multiple resonance thermally activated delayed fluorescence (MR-TADF) framework with three graded donor groups—9,10-dihydro-9,9-dimethylacidine, phenothiazine, and phenoloxazine—through covalent linkage and cyclization to construct a donor-acceptor synergistic system. This system achieves a three-in-one performance of high fluorescence quantum yield, resistance to aggregation-induced fluorescence quenching, and high color purity. It solves the inherent defects of existing MR-TADF materials, such as the planar structure's susceptibility to aggregation-induced quenching and the lack of high quantum yield and color purity in simple macrocyclic materials. It organically combines the high exciton utilization and high color purity advantages of MR-TADF with the anti-aggregation properties of macrocyclic materials, achieving a synergistic effect of 1+1>2.

[0023] 2. This invention employs a two-step cyclization strategy involving Buchwald-Hartwig coupling and Friedel-Crafts alkylation. The synthetic route is simple and efficient, combining the advantages of modular design with process adaptability. By changing the donor raw materials or adjusting the reaction ratio, macrocyclic homologues with different cavity sizes and luminescent properties can be constructed without significantly altering the reaction process, thus meeting the diverse needs of large-scale production.

[0024] 3. The macrocyclic compound designed in this invention possesses both chemical stability and structural rigidity, ensuring the long-term stable operation of OLED devices. The high bond energy of the CN bond formed by Buchwald-Hartwig coupling, the covalent connection between the boron-oxygen multi-resonance thermally activated delayed fluorescence framework and the rigid heterocyclic donor, prevents molecular chain breakage. Cyclic voltammetry tests show that the target product has a clear redox peak, exhibiting excellent high-temperature resistance and redox resistance. The three-dimensional structure of the macrocycle synergistically with the rigid heterocyclic characteristics of the donor group locks the molecular conformation, reducing non-radiative transitions caused by structural relaxation. This not only improves color purity and radiative transition rate but also reduces the risk of material degradation during device operation, extending the service life of OLED devices. Attached Figure Description

[0025] Figure 1 The above is the 1H NMR spectrum of compound A in Example 1 of this invention;

[0026] Figure 2 The 1H NMR spectrum of macrocyclic compound B3 in Example 1 of this invention;

[0027] Figure 3 This is the mass spectrum of macrocyclic compound B3 in Example 1 of the present invention;

[0028] Figure 4 The ultraviolet absorption spectra of compound A and macrocyclic compound B3 in Example 1 of this invention are shown below.

[0029] Figure 5The fluorescence emission spectra of compound A and macrocyclic compound B3 in Example 1 of this invention are shown.

[0030] Figure 6 This is the cyclic voltammogram of macrocyclic compound B3 in Example 1 of the present invention. Detailed Implementation

[0031] Unless otherwise specified, all materials and instruments used below are commercially available products, and all methods used are conventional methods in this field.

[0032] The two reactions involved in this invention are: (1) Buchwald-Hartwig coupling, a palladium-catalyzed reaction used to couple aryl halides with amines or amides to synthesize aromatic or acyl aromatic amines; and (2) Friedel-Crafts alkylation, a class of aromatic electrophilic substitution reactions, mainly including alkylation and acylation reactions, usually carried out under Lewis acid catalysis.

[0033] An organic light-emitting macrocyclic material based on a boron-oxygen structure, with the following structural formula:

[0034]

[0035] Where n represents The number of repeating units, n, takes the value of 3 or 4, and the Donor group is selected from one of the following groups:

[0036] .

[0037] In this invention, "Donor" refers to a donor, specifically a functional group with electron-donating capabilities. Its core function is to provide electrons to the boron-oxygen multiple resonance thermally activated delayed fluorescence (MR-TADF) framework, forming a donor-acceptor (DA) synergistic structure with the framework, thereby regulating the luminescence properties of the material, such as fluorescence quantum yield, emission wavelength, and color purity.

[0038] The organic light-emitting macrocyclic material of this invention is based on a boron-oxygen multi-resonance thermally activated delayed fluorescence backbone (compound II) covalently linked with 9,10-dihydro-9,9-dimethylacridinium, phenothiazine, and phenoloxazine groups, cyclized via Buchwald-Hartwig coupling and Friedel-Crafts alkylation. The material of this invention exhibits high fluorescence quantum yield and effectively suppresses fluorescence quenching caused by aggregation. The synthesis method provided by this invention is simple and efficient, allowing for modular selection of the MR-TADF backbone and donor units to control the luminescent properties of the material, constructing macrocyclic homologues with varying cavity sizes. Applying the multi-resonance thermally activated delayed fluorescence material of this invention to organic electroluminescent devices can effectively improve device efficiency and stability, providing a development direction for next-generation OLED display technology.

[0039] The boron-oxygen multi-resonance thermally activated delayed fluorescence backbone is covalently linked with 9,10-dihydro-9,9-dimethylacidine, phenthiazine, and phenoloxazine groups, and then formed into a macrocycle through cyclization, which can achieve a synergistic effect of 1+1>2: it retains the core advantages of MR-TADF, and solves the problem of fluorescence quenching caused by aggregation by using the macrocycle structure.

[0040] The boron-oxygen multiple resonance thermally activated delayed fluorescence (DA) framework is essentially an electron acceptor. Boron atoms are highly electropositive and readily accept electrons, while 9,10-dihydro-9,9-dimethylacidine, phenothiazine, and phenoloxazine are electron donors. The covalent connection of these two components forms a DA-synergistic structure, which can regulate the frontier orbital distribution of the molecule, reduce the singlet-triplet energy level difference (ΔEST), promote the thermally activated delayed fluorescence process, optimize the radiative transition rate, and improve the fluorescence quantum yield (refer to Example 1, where the fluorescence quantum yield of macrocyclic compound B3 is 70%, higher than that of compound A at 63.7%). This allows for precise control of the emission wavelength (refer to Example 1, macrocyclic compound B3 is redshifted by 27 nm compared to compound A), adapting to the different emission colors required by OLEDs.

[0041] This invention is the first to achieve covalent linkage between a boron-oxygen multi-resonance thermally activated delayed fluorescence (MR-TADF) framework and a donor via Buchwald-Hartwig coupling, followed by intramolecular cyclization via Friedel-Crafts alkylation. A key challenge of existing MR-TADF materials is aggregation-induced fluorescence quenching. This invention, through the three-dimensional structure formed by donor linkage and macrocyclic cyclization, spatially hinders close molecular packing. Simultaneously, the DA interaction between the donor groups and the boron-oxygen framework optimizes electron distribution, ultimately achieving synergistic performance of high fluorescence quantum yield, inhibition of aggregation-induced fluorescence quenching, and high color purity—achievable by existing single MR-TADF materials or simple macrocyclic materials. This invention, through the modular design of selecting different donor groups and regulating the macrocyclic repeating unit n (3 or 4), can flexibly control the emission wavelength, quantum yield, and other properties of the material, and construct macrocyclic homologs with different cavity sizes, such as macrocyclic compounds B3, B4, D3, D4, F3, and F4 in the examples, to meet the diverse color material requirements of next-generation OLEDs.

[0042] Meanwhile, the 9,10-dihydro-9,9-dimethylacrimidine, phenthiazine, and phenoloxazine groups were not randomly selected, but rather preferred options selected based on electronic structure compatibility, cyclization reaction compatibility, and performance controllability. Their uniqueness is as follows:

[0043] (1) All three groups are electron-donating groups of moderate strength, but there are slight differences in electron-donating ability: 9,10-dihydro-9,9-dimethylacridine contains aliphatic amine N atoms, and the lone pair electrons of the N atoms are easily delocalized, resulting in a strong electron-donating ability; phenthiazide contains sulfur heterocycles, and the lone pair electrons of the S atoms are conjugated with the aromatic ring, resulting in a slightly weaker electron-donating ability than acridine, and a moderate electron-donating ability; phenoloxazine contains oxygen heterocycles, and the O atoms are more electronegative than S, resulting in a slightly weaker lone pair electron delocalization and a slightly weaker electron-donating ability. This gradient electron-donating ability can form DA interactions of different strengths with the boron-oxygen multiple resonance thermally activated delayed fluorescence framework, thereby precisely controlling the frontier orbital energy level difference (ΔEST) and luminescence properties (such as emission wavelength and quantum yield) of the material, and achieving the design goal of tunable performance.

[0044] (2) All three groups are rigid heterocyclic aromatic structures with moderate steric hindrance: the molecular size matches the boron-oxygen multiple resonance thermally activated delayed fluorescence backbone, and can be successfully covalently linked to the backbone in the Buchwald-Hartwig coupling reaction (the yields of Examples 1-3 were 57%, 33%, and 39%, respectively, proving that the reaction compatibility is good); the heterocyclic structure of the groups has a certain rigidity, and after linkage, the cyclization will not be difficult due to excessive molecular flexibility, and can cooperate with the three-dimensional structure of the macrocycle to further lock the molecular conformation, suppress nonradiative transitions, and improve color purity.

[0045] (3) All three groups are aromatic heterocyclic compounds with high chemical stability: they are not easy to decompose during the preparation process and long-term operation of OLED devices, which can improve the stability of the device. After covalently connecting with the boron-oxygen multiple resonance thermally activated delayed fluorescence backbone, the CN bond (Buchwald-Hartwig coupling product) formed has a high bond energy, which further enhances the chemical stability of the molecule and avoids the light emission failure caused by the breakage of chemical bonds when the device is working.

[0046] A method for preparing an organic light-emitting macrocyclic material based on a boron-oxygen structure includes:

[0047]

[0048] Step 1: 2,5-Dibromo-1,3-difluorobenzene, p-tert-butylphenol and potassium carbonate were added to N-methylpyrrolidone, reacted under a protective gas and then purified to obtain compound I;

[0049] Step 2: Under a protective gas atmosphere, n-butyllithium was added to a toluene solution of compound I, followed by the addition of boron tribromide and N,N-diisopropylethylamine. After reaction and purification, compound II was obtained.

[0050] Step 3: Compound II and the donor raw material (a raw material containing a Donor group) are added to an organic solvent. The donor raw material is 9,10-dihydro-9,9-dimethylacrimidine, phenthiazide, or phenoloxazine. A base is added, and under a protective gas, a palladium catalyst and a phosphine ligand are added. After the reaction, the mixture is purified to obtain compound III.

[0051] Step 4: Compound III is added to an organic solvent, and under a protective gas atmosphere, paraformaldehyde and an acid catalyst are added. After the reaction, the mixture is purified to obtain compound IV, which is an organic light-emitting macrocyclic material based on a boron-oxygen structure.

[0052] In a preferred embodiment, the organic solvent in step 3 is one of toluene, o-xylene, and m-xylene.

[0053] In a preferred embodiment, the base in step 3 is one of Na2CO3, K2CO3, KOH, t-BuONa, and NaOH. Choosing toluene / o-xylene / m-xylene as the solvent and Na2CO3 / K2CO3 / KOH / t-BuONa / NaOH as the base adapts to the solubility of the donor group and the reaction temperature requirements (110-140℃), avoiding the hydrolysis of the boron-oxygen framework or decomposition of the donor caused by conventional solvents / bases.

[0054] In a preferred embodiment, the palladium catalyst in step 3 is Pd(OAc)2, PdCl2, Pd2(dba)3, Pd(PPh2)Cl2, or Pd(dppf)Cl2.

[0055] In a preferred embodiment, the phosphine ligand in step 3 is 2-di-tert-butylphosphine-2',4',6'-triisopropyl-3,6-dimethoxy-1,1'-biphenyl, tri-tert-butylphosphine, PPh3, P( t One of Pd(OAc)2, Pd2(dba)3, and Pd(dppf)Cl2 was selected. Specific palladium catalysts, such as Pd(OAc)2, Pd2(dba)3, and Pd(dppf)Cl2, and phosphine ligands, such as 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl and P(tBu)3·BF4, were screened to address the stability of the boron-oxygen multiple resonance thermally activated delayed fluorescence framework and the heterocyclic structure of the donor group. This avoided coordination interference between the catalyst and the boron-oxygen framework, ensuring the efficiency of CN bond formation (yields of 57%, 33%, and 39% in Examples 1-3, respectively).

[0056] In a preferred embodiment, the solvent in step 4 includes one of dichloromethane, chloroform, and 1,2-dichloroethane. Choosing dichloromethane / chloroform / 1,2-dichloroethane as the solvent and controlling the reaction time to 2-6 hours ensures sufficient macrocyclization while avoiding the formation of byproducts due to excessive alkylation (e.g., in Example 1, the yields of macrocyclic compounds B3 and B4 were 28% and 7%, respectively, and the product purity was verified by NMR and mass spectrometry).

[0057] In a preferred embodiment, the catalyst in step 4 is one of boron trifluoride diethyl ether, FeCl3·6H2O, and trifluoroacetic acid. Mild acid catalysts such as FeCl3·6H2O, boron trifluoride diethyl ether, and trifluoroacetic acid were screened to avoid the destruction of the multiple resonance structure of MR-TADF under strongly acidic conditions.

[0058] In a preferred embodiment, the reaction temperature in step 1 is 180°C. The reaction in step 1 is essentially a nucleophilic aromatic substitution reaction. p-tert-butylphenol undergoes deprotonation in the presence of potassium carbonate to form a phenolate, which then attacks the aromatic ring of 2,5-dibromo-1,3-difluorobenzene, replacing the fluorine atom to form a CO bond, ultimately generating compound I. The choice of a high temperature of 180°C is crucial to meeting the thermodynamic and kinetic requirements of this SNAr reaction, ensuring the efficient and high-purity synthesis of compound I.

[0059] In a preferred embodiment, the reaction temperature in step 4 is room temperature. Step 4 involves the ring formation of the core functional structure, which requires mild room temperature conditions to protect the luminescence properties of the boron-oxygen multi-resonance thermally activated delayed fluorescence backbone, avoid side reactions, ensure the regularity of the macrocyclic structure, and ultimately achieve synergistic performance of high fluorescence quantum yield, resistance to aggregation quenching, and high color purity.

[0060] The organic light-emitting macrocyclic materials based on boron-oxygen structures provided by this invention are macrocyclic compounds B3, B4, D3, D4, F3, and F4.

[0061] Example 1

[0062] This embodiment provides the structures and reaction routes of macrocyclic compounds B3 and B4:

[0063]

[0064] (1) Synthesis of Compound I: 1.51 g (5.52 mmol) of 2,5-dibromo-1,3-difluorobenzene, 2.5 g (16.56 mmol) of p-tert-butylphenol, and 2.29 g (16.56 mmol) of potassium carbonate were weighed and added to a 50 mL double-necked round-bottom flask under argon protection. 6.7 mL of N-methylpyrrolidone was added to the reaction flask, and the mixture was heated to 180 °C and reacted for 12 h. The reaction progress was monitored by thin-layer chromatography (TLC). After the reaction was complete, 150 mL of ice water was slowly added, and the mixture was stirred at 0 °C for 1 h. The mixture was then filtered, and the filter cake was extracted with dichloromethane and water. The extract was dried over anhydrous sodium sulfate and concentrated. Column chromatography was performed using petroleum ether as the eluent to obtain a white solid (Compound I) with a yield of 64%. 1H NMR spectrum of Compound I: 1 HNMR (400MHz, Chloroform- d ): δ 7.40(d, J =8.0Hz,2H),6.99(d, J =8.0Hz,2H),6.73(s,1H),1.34(s,9H).

[0065] (2) Synthesis of Compound II: Compound I (1.06 g, 2 mmol) was weighed and added to a 250 mL three-necked round-bottom flask. Under argon protection, 50 mL of toluene was added and stirred to dissolve. Under ice bath conditions, a 1.6 M n-butyllithium solution (dissolved in n-hexane) (1.37 mL, 2.2 mmol) was slowly added dropwise to the toluene solution of Compound I. After the addition was complete, the mixture was stirred for 20 minutes and then brought to room temperature. The mixture was stirred at room temperature for 2 hours, and the reaction was monitored by TLC. Subsequently, the reaction system was placed at -40 °C, and boron tribromide (0.39 mL, 4 mmol) was slowly added dropwise to the reaction system. After the addition was complete, the mixture was stirred for 20 minutes and then brought to room temperature. The mixture was stirred at room temperature for 1 hour, and the reaction progress was monitored by TLC (at this time, yellow fluorescent spots were generated). After the reaction was complete, the system was kept in an ice bath. DIEA (N,N-diisopropylethylamine) (0.7 mL, 4 mmol) was slowly added dropwise to the reaction system. After the addition was complete, the mixture was stirred for 20 minutes and then allowed to return to room temperature. The mixture was stirred at 120 °C for 12 h, and the reaction was monitored by TLC. After the reaction was complete, a suitable amount of dichloromethane was added, and the mixture was extracted three times with 50 mL of saturated saline solution. The dichloromethane phase extract was collected, dried over anhydrous sodium sulfate, and concentrated. Column chromatography was performed using petroleum ether as the eluent to obtain a white solid with a yield of 18%. The 1H NMR spectrum of compound II is as follows: 1 HNMR (400MHz, Chloroform- d ): δ 8.73 (s, 2H), 7.79 (d, J=8.0Hz,2H),7.47(d, J =8.0Hz,2H),7.35(s,2H),1.48(s,18H).

[0066] (3) Synthesis of Compound A: Compound II (461 mg, 1 mmol) and 9,10-dihydro-9,9-dimethylacridine (209 mg, 1.1 mmol) were weighed and added to 50 mL of toluene. Under argon protection, palladium acetate (11.2 mg, 0.05 mmol) and 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (47.7 mg, 0.1 mmol) were added sequentially to a 100 mL two-necked round-bottom flask. Finally, sodium tert-butoxide (288 mg, 3 mmol) was added. The reaction was carried out at 110 °C for 12 h, and the reaction progress was monitored by TLC. After the reaction was completed, the mixture was cooled to room temperature, and an appropriate amount of dichloromethane was added. The mixture was extracted three times with 50 mL of saturated brine. The dichloromethane phase extract was collected, dried over anhydrous sodium sulfate, and concentrated. The separation was performed by column chromatography using petroleum ether:dichloromethane (3:1, V / V, V / V refers to the volume ratio) as the eluent. The product was recrystallized in dichloromethane and n-hexane solvent to obtain white crystals with a yield of 57%. Figure 1 The 1H NMR spectrum of compound A is given: 1 HNMR (400MHz, Chloroform- d ) δ 8.79 (s, 2H), 7.80 (d, J =8.8Hz,2H),7.54–7.46(m,4H),7.22(s,2H),7.04–6.93(m,4H),6.50(d, J =7.7Hz,2H),1.72(s,6H),1.51(s,18H).

[0067] (4) Synthesis of macrocyclic compounds B3 and B4: Compound A (100 mg, 0.17 mmol) was weighed and added to a 100 mL single-necked round-bottom flask. 30 mL of 1,2-dichloroethane was added and stirred to dissolve. Paraformaldehyde (15 mg, 0.51 mmol) was added under a 30 °C water bath, followed by FeCl3·6H2O (22.5 mg, 0.017 mmol). After the addition was complete, the mixture was stirred at room temperature (25 °C) for about 6 h (the color of the reaction system gradually deepened). The reaction progress was monitored by TLC every 1 h. After the reaction was completed, an appropriate amount of water was added to quench the reaction. Then, dichloromethane and 50 mL of saturated saline solution were added for extraction three times. The dichloromethane phase extract was collected, dried with anhydrous sodium sulfate, and concentrated. Separation was performed using column chromatography with petroleum ether:dichloromethane (2:1, V / V) as eluent. The products were recrystallized from dichloromethane and n-hexane to give macrocyclic compounds B3 and B4, with yields of 28% and 7%, respectively. The 1H NMR spectrum of macrocyclic compound B3 was obtained. Figure 2 ): 1 HNMR (400MHz, Chloroform- d ) δ 8.79 (s, 6H), 7.80 (d, J =8.9Hz, 6H), 7.50(d, J =8.9Hz, 6H), 7.19(s, 6H), 6.99(d, J =8.6Hz, 6H), 6.63(d, J =8.3 Hz, 6H), 3.93 (s, 6H), 1.58 (s, 18H), 1.51 (s, 54H). Mass spectra of macrocyclic compound B3 ( Figure 3 ): MALDI-TOF(m / z)[M+H] + calcd.forC 126 H 121 B3N3O6 1804.9579; found 1804.0848. 1H NMR spectrum of macrocyclic compound B4: 1 HNMR (400MHz, Chloroform-d) δ 8.76 (s, 8H), 7.75 (d, J =8.9Hz,8H),7.50–7.41(m,8H),7.18(dd, J =19.0, 2.7 Hz, 8H), 6.87 (d, J =8.5Hz, 8H), 6.42(d, J=8.8 Hz, 8H), 3.87 (s, 8H), 1.63 (s, 24H), 1.60 (s, 72H). Mass spectrum of macrocyclic compound B4: MALDI-TOF (m / z) [M+H] + calcd.forC 168 H 160 B4N4O82407.2766;found2407.7300.

[0068] The UV-Vis absorption spectroscopy and fluorescence emission spectroscopy of compound A and macrocyclic compound B3 prepared in Example 1 were performed at room temperature (concentration 1×10⁻⁶). -5 (mol / L, solvent is toluene). UV-Vis absorption spectrum as follows: Figure 4 As shown, the maximum absorption wavelength of both compound A and macrocyclic compound B3 is 380 nm. The fluorescence emission spectra are as follows: Figure 5 As shown, under 380 nm excitation conditions, the strongest emission wavelengths of compound A and macrocyclic compound B3 are 460 nm and 487 nm, respectively, with the macrocyclic trimer exhibiting a 27 nm redshift compared to the monomer. The fluorescence quantum yields of compounds A and B3 in toluene solvent (concentration 1 × 10⁻⁶) were also measured. -5 The fluorescence quantum yields (63.7% and 70% at mol / L and excitation wavelength of 380 nm) were respectively, indicating that the fluorescence quantum yield was significantly improved after cyclization.

[0069] Simultaneously, cyclic voltammetry was performed on the macrocyclic compound B3 prepared in Example 1. A platinum-carbon electrode was used as the working electrode, a platinum wire electrode as the reference and counter electrode, and a mixed solution of acetonitrile and toluene (1:1, V / V) in 0.1 mol / L TPAPF6 was used as the electrolyte. The scan rate was 0.1 V / s, and the reference electrode ratio was Fc / Fc. + .like Figure 6 As shown, two oxidation peaks and two reduction peaks can be observed, with an initial oxidation potential of 0.28V and a reduction potential of -2.47V.

[0070] Example 2

[0071] This embodiment provides synthetic routes for macrocyclic compounds D3 and D4:

[0072]

[0073] (1) Synthesis of compound C: Weigh compound II (461 mg, 1 mmol), phenothiazine (259 mg, 1.3 mmol), add 50 mL of o-xylene, and under argon protection, add Pd2(dba)3 (18.3 mg, 0.02 mmol), P( tBu3·BF4 (43.5 mg, 0.15 mmol) was added sequentially to a 100 mL double-necked round-bottom flask, followed by sodium tert-butoxide (288 mg, 3 mmol). The reaction was carried out at 140 °C for 12 h, and the reaction progress was monitored by TLC. After the reaction was completed, the mixture was cooled to room temperature, and a suitable amount of dichloromethane was added. The mixture was extracted three times with 50 mL of saturated brine. The dichloromethane phase extract was collected, dried over anhydrous sodium sulfate, and concentrated. Separation was performed by column chromatography using petroleum ether:dichloromethane (3:1, V / V) as the eluent. The product was recrystallized from dichloromethane and n-hexane to give white crystals in a yield of 33%. The 1H NMR spectrum of compound C is as follows: 1 HNMR (400MHz, Chloroform- d ) δ 8.71(d, J =2.9Hz,2H),7.72(d, J =8.6Hz,2H),7.44–7.35(m,4H),7.29(s,4H),7.16(s,2H),6.92(s,2H),1.48(s,18H).

[0074] (2) Synthesis of macrocyclic compounds D3 and D4: Compound C (500 mg, 0.51 mmol) was weighed and added to a 250 mL reaction flask. 200 mL of dichloromethane was added and stirred to dissolve. Paraformaldehyde (45 mg, 1.53 mmol) was added in a 30 °C water bath, followed by boron trifluoride ether (0.1 mL, 0.51 mmol). After the addition was complete, the mixture was stirred at room temperature for about 2 h (the color of the reaction system gradually deepened). The reaction progress was monitored by TLC every 20 minutes. After the reaction was completed, an appropriate amount of water was added to quench the reaction. Then, dichloromethane and 50 mL of saturated brine were added for extraction three times. The dichloromethane phase extract was collected, dried with anhydrous sodium sulfate, and concentrated. The product was separated and purified by column chromatography using petroleum ether:dichloromethane (2:1, V / V) as the eluent. The product was recrystallized from dichloromethane and n-hexane to obtain macrocyclic compounds D3 and D4, with yields of 18% and 4%, respectively.

[0075] In Example 2, after cyclization, the phenothiazine donor and the boron-oxygen multiple resonance thermally activated delayed fluorescence backbone form a stable donor-acceptor (DA) synergistic system, effectively reducing the singlet-triplet energy level difference, promoting the thermally activated delayed fluorescence process, and improving the fluorescence quantum yield. Macrocyclic compounds D3 and D4 have three-dimensional macrocyclic structures, which can spatially hinder close packing between molecules and significantly suppress fluorescence quenching caused by aggregation. The high bond energy of the CN bond formed by Buchwald-Hartwig coupling, the strong chemical stability of the aromatic heterocyclic structure of phenothiazine, and the rigid three-dimensional structure of the macrocycle give macrocyclic compounds D3 and D4 good high-temperature resistance and redox resistance.

[0076] Example 3

[0077] This embodiment provides synthetic routes for macrocyclic compounds F3 and F4:

[0078]

[0079] (1) Synthesis of compound E: Compound II (461 mg, 1 mmol), phenoloxazine (201 mg, 1.1 mmol), and 50 mL of m-xylene were weighed. Under argon protection, Pd(dppf)Cl2 (14.6 mg, 0.02 mmol) and tri-tert-butylphosphine (30.3 mg, 0.15 mmol) were added sequentially to a 100 mL two-necked round-bottom flask. Finally, sodium tert-butoxide (288 mg, 3 mmol) was added. The reaction was carried out at 120 °C for 12 h, and the reaction progress was monitored by TLC. After the reaction was completed, the mixture was cooled to room temperature, and an appropriate amount of dichloromethane was added. The mixture was extracted three times with 50 mL of saturated brine. The dichloromethane phase extract was collected, dried with anhydrous sodium sulfate, and concentrated. The product was separated by column chromatography using petroleum ether:dichloromethane (3:1, V / V) as the eluent. The product was recrystallized from dichloromethane and n-hexane solvent to obtain white crystals with a yield of 39%.

[0080] (2) Synthesis of macrocyclic compounds F3 and F4: Compound E (100 mg, 0.18 mmol) was weighed and added to a 100 mL single-necked round-bottom flask. 30 mL of chloroform was added and stirred to dissolve. Paraformaldehyde (16 mg, 0.54 mmol) was added in a 30 °C water bath, followed by trifluoroacetic acid (0.2 mL, 2.7 mmol). After the addition was complete, the mixture was stirred at room temperature for about 3 h (the color of the reaction system gradually deepened). The reaction progress was monitored by TLC every 30 minutes. After the reaction was completed, an appropriate amount of water was added to quench the reaction. Then, dichloromethane and 50 mL of saturated brine were added for extraction three times. The dichloromethane phase extract was collected, dried with anhydrous sodium sulfate, and concentrated. The product was separated by column chromatography using petroleum ether:dichloromethane (2:1, V / V) as the eluent. The product was recrystallized from dichloromethane and n-hexane to obtain macrocyclic compounds F3 and F4, with yields of 24% and 5%, respectively.

[0081] In Example 3, after cyclization, the phenoloxazine donor and the boron-oxygen multiple resonance thermally activated delayed fluorescence backbone form a stable donor-acceptor (DA) synergistic system, effectively reducing the singlet-triplet energy level difference, promoting the thermally activated delayed fluorescence process, and improving the fluorescence quantum yield. Macrocyclic compounds F3 and F4 have three-dimensional macrocyclic structures, which can spatially hinder close packing between molecules and significantly suppress fluorescence quenching caused by aggregation. The high bond energy of the CN bond formed by Buchwald-Hartwig coupling, the strong chemical stability of the aromatic heterocyclic structure of phenoloxazine, combined with the rigid three-dimensional structure of the macrocycle, give macrocyclic compounds F3 and F4 good high-temperature resistance and redox resistance.

[0082] The main drawback of existing MR-TADF materials is the trade-off between high color purity and resistance to aggregation quenching. Planar structures ensure high color purity but are prone to aggregation quenching; while simple macrocyclic materials lack the high quantum yield of MR-TADF. This invention achieves DA synergy between the framework and donor through Buchwald-Hartwig coupling, optimizing quantum yield, and suppresses aggregation quenching through Friedel-Crafts alkylation, thus realizing for the first time a synergistic performance of high fluorescence quantum yield, resistance to aggregation quenching, and high color purity.

[0083] Compound A (conjugated only by Buchwald-Hartwig coupling, not cyclized) has a fluorescence quantum yield of 63.7%. After Friedel-Crafts alkylation and cyclization, the resulting macrocyclic compound B3 exhibits a fluorescence quantum yield increase to 70%, representing a 10% improvement. This improvement is not a typical effect of cyclization; conventional macrocyclization may result in a decrease or no change in quantum yield due to increased molecular rigidity. Conventional TADF materials typically have fluorescence quantum yields between 50% and 80%, while the product of this invention reaches a mid-to-high level, further enhanced after cyclization.

[0084] The target product of this invention is a three-dimensional macrocyclic structure. The macrocyclic molecule possesses a three-dimensional structure, which spatially hinders close molecular packing and suppresses fluorescence quenching caused by aggregation. This is the structural basis for its resistance to aggregation quenching. In existing technologies, planar MR-TADF materials are prone to aggregation quenching due to close packing. In Example 1, the fluorescence quantum yield of macrocyclic compound B3 (70%) was significantly higher than that of the non-cyclic compound A (63.7%). If the material suffers from severe aggregation quenching, the probability of molecular aggregation increases after cyclization, and the quantum yield should decrease or remain the same. However, the quantum yield of this invention actually increases after cyclization, indicating that the three-dimensional macrocyclic structure successfully hinders molecular aggregation and effectively suppresses fluorescence quenching caused by aggregation, thus confirming its resistance to aggregation quenching.

[0085] The core evaluation index of color purity is the full width at half maximum (FWHM) of the fluorescence emission spectrum. A narrower FWHM indicates higher color purity, and one of the core advantages of MR-TADF materials is their narrow FWHM and high color purity. Example 1 demonstrates high color purity through spectral data and structural design. Example 1... Figure 5 The fluorescence emission spectrum shows that the fluorescence emission peak of macrocyclic compound B3 is a sharp and symmetrical peak without obvious broadening. Combined with the inherent characteristics of MR-TADF materials, this invention retains the multiple resonance structure of the boron-oxygen MR-TADF framework and further locks the molecular conformation through macrocyclization, suppressing structural relaxation and nonradiative transitions, avoiding emission peak broadening, and ensuring high color purity. After ring formation, the emission wavelength is red-shifted by 27 nm, achieving precise wavelength control without destroying the multiple resonance structure of MR-TADF. However, the peak shape remains sharp and there is no broadening or splitting, indicating that the color purity is not affected during wavelength control, further confirming the high color purity stability of the material of this invention.

[0086] Cyclic voltammetry tests showed that macrocyclic compound B3 has distinct redox peaks, with an initial oxidation potential of 0.28 V and a reduction potential of -2.47 V, proving that the molecular structure is stable and suitable for the long-term operation requirements of OLED devices, which cannot be achieved by simply connecting donors or simply forming rings.

[0087] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An organic light-emitting macrocyclic material based on boron-oxygen structure, characterized in that, The structural formula is: or .

2. The method for preparing organic light-emitting macrocyclic materials based on boron-oxygen structures according to claim 1, characterized in that, include: ； Step 1: 2,5-Dibromo-1,3-difluorobenzene, p-tert-butylphenol and potassium carbonate were added to N-methylpyrrolidone, reacted under a protective gas and then purified to obtain compound I; Step 2: Under a protective gas atmosphere, n-butyllithium was added to a toluene solution of compound I, followed by the addition of boron tribromide and N,N-diisopropylethylamine. After reaction and purification, compound II was obtained. Step 3: Compound II and the donor raw material are added to an organic solvent. The donor raw material is 9,10-dihydro-9,9-dimethylacridine. A base is added, and under a protective gas, a palladium catalyst and a phosphine ligand are added. After reaction and purification, compound A is obtained. Step 4: Compound A is added to an organic solvent, and under a protective gas atmosphere, paraformaldehyde and an acid catalyst are added. After the reaction, the mixture is purified to obtain macrocyclic compounds B3 and B4 based on boron-oxygen structures.

3. The method for preparing organic light-emitting macrocyclic materials based on boron-oxygen structures according to claim 2, characterized in that: The organic solvent in step 3 is one of toluene, o-xylene, and m-xylene.

4. The method for preparing organic light-emitting macrocyclic materials based on boron-oxygen structures according to claim 2, characterized in that: The alkali used in step 3 is one of Na2CO3, K2CO3, KOH, t-BuONa, and NaOH.

5. The method for preparing organic light-emitting macrocyclic materials based on boron-oxygen structures according to claim 2, characterized in that: The palladium catalyst in step 3 is Pd(OAc)2 or PdCl2 or Pd2(dba)3 or Pd(PPh2)Cl2 or Pd(dppf)Cl2.

6. The method for preparing organic light-emitting macrocyclic materials based on boron-oxygen structures according to claim 2, characterized in that: The phosphine ligand in step 3 is 2-di-tert-butylphosphine-2',4',6'-triisopropyl-3,6-dimethoxy-1,1'-biphenyl, tri-tert-butylphosphine, PPh3, P( t One of Bu)3·BF4 and 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl.

7. The method for preparing organic light-emitting macrocyclic materials based on boron-oxygen structures according to claim 2, characterized in that: The organic solvent in step 4 includes one of dichloromethane, chloroform, and 1,2-dichloroethane.

8. The method for preparing organic light-emitting macrocyclic materials based on boron-oxygen structures according to claim 2, characterized in that: The catalyst in step 4 is one of boron trifluoride diethyl ether, FeCl3·6H2O, and trifluoroacetic acid.

9. The method for preparing organic light-emitting macrocyclic materials based on boron-oxygen structures according to claim 2, characterized in that: In step 1, the reaction temperature is 180℃.

10. The method for preparing organic light-emitting macrocyclic materials based on boron-oxygen structures according to claim 2, characterized in that: In step 4, the reaction temperature is room temperature.

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