Boron-nitrogen heterocyclic compound with non-conjugated structure as well as preparation method and application of boron-nitrogen heterocyclic compound

Abstract

The invention provides a boron-nitrogen heterocyclic compound with a non-conjugated structure and a preparation method and application thereof, and belongs to the technical field of organic electroluminescent materials, the boron-nitrogen heterocyclic compound takes a single boron-nitrogen heterocyclic ring as an end group, the end group is connected through a central non-conjugated group to form the non-conjugated structure, the interaction among molecules is weakened, the exciton annihilation probability is reduced, the material PLQY is improved, and the performance of the material is improved. The narrow-band emission is realized, the thermal stability is good, and the design of the device and the improvement of the performance are facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of organic electroluminescent materials, and in particular relates to a boron-nitrogen heterocyclic compound with a non-conjugated structure, a preparation method and an application thereof. Background Art

[0002] Organic light-emitting diodes (OLED) have received widespread attention in the display and lighting fields around the world. At present, industrialization has been achieved in the fields of smartphones, smart displays, etc. However, the half-width of the luminescence of the mainstream luminescent materials on the market cannot meet the requirements of ultra-high-definition display (BT.2020), and improving color purity through filtering technology not only increases the difficulty and cost of device preparation, but also reduces material performance. Therefore, through chemical methods, constructing narrow-band, high-performance OLED luminescent materials from the source can not only meet the requirements of ultra-high-definition display, but also reduce production costs and improve competitiveness. From the current development, multi-resonance (MR)-OLED materials are a type of OLED materials that have narrow luminescence bands, high performance and stability, and have great application potential. Summary of the invention

[0003] In order to solve the above-mentioned technical problems, the present invention provides a boron nitrogen heterocyclic compound with a non-conjugated structure and a preparation method and application thereof, which uses a single boron nitrogen heterocyclic ring as an end group and is connected through a central non-conjugated group to form a non-conjugated structure, thereby weakening the interaction between molecules, reducing the probability of exciton annihilation, improving the PLQY of the material, achieving narrow-band emission, having good thermal stability, and being beneficial to the design of the device and improving performance.

[0004] The present invention provides a boron-nitrogen heterocyclic compound having a non-conjugated structure, and the general structural formula of the boron-nitrogen heterocyclic compound is as follows:

[0005] Wherein, Ar1 is selected from one of an alkane having a non-conjugated structure, a cycloalkane having a non-conjugated structure, an alkene having a non-conjugated structure, an alkyne having a non-conjugated structure, and a group having a spatial configuration;

[0006] Ar2 is selected from a combination of one or more of a fluorine atom, a bromine atom, a chlorine atom, a cyano group, an alkyl group, an aromatic ring composed of carbon and hydrogen atoms, and an aromatic heterocycle composed of carbon, nitrogen and hydrogen atoms;

[0007] Ar3 is selected from one or more combinations of a fluorine atom, a bromine atom, a chlorine atom, a cyano group, an alkyl group, an aromatic ring composed of carbon and hydrogen atoms, and an aromatic heterocycle composed of carbon, nitrogen and hydrogen atoms.

[0008] In some embodiments, the Ar1 is selected from one of Formula IV:

[0009]

[0010] In some embodiments, Ar2 is selected from one of Formulas I-XII:

[0011]

[0012] In some embodiments, Ar3 is selected from one of Formulas I-XII:

[0013]

[0014] In some embodiments, the boron nitrogen heterocyclic compound is selected from one of Formulas 1-60:

[0015]

[0016]

[0017] The second object of the present invention is to provide a method for preparing a boron nitrogen heterocyclic compound with a non-conjugated structure, the preparation method specifically comprising: synthesizing a double boron nitrogen heterocyclic precursor by a Hartwig-Buchwald reaction, and then synthesizing it by a borylation reaction.

[0018] In some embodiments, the parameters of the Hartwig-Buchwald reaction are as follows: temperature is 110° C., and time is ≥12 h.

[0019] In some embodiments, the parameters of the borylation reaction are as follows: temperature is 200° C., and time is ≥12 h.

[0020] The third object of the present invention is to provide an application of a boron-nitrogen heterocyclic compound in the preparation of a thermally activated delayed fluorescent material.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The non-conjugated boron-nitrogen heterocyclic compound provided in the present invention can be used as a thermally activated delayed fluorescent material. By utilizing the non-conjugated unit and isolating the two parts of the boron-nitrogen luminescent core, a highly efficient narrow-band blue light emitting thermally activated delayed fluorescent device can be prepared.

[0023] (2) The boron-nitrogen heterocyclic compound of the present invention has a luminescence peak at about 450 nm and is a type of organic blue light guest material with high luminescence color purity.

[0024] (3) By changing the modifying groups and isolating groups on the aromatic structure, the physical properties of the material can be further improved, which can give the device better performance when used in organic semiconductor devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is the absorption and emission spectra of compound 5 prepared in the embodiment of the present invention in tetrahydrofuran solution;

[0026] Figure 2 is a thermogravimetric analysis and differential scanning calorimetry curve diagram of compound 5 prepared in an example of the present invention;

[0027] Figure 3 5 is the frontier orbital distribution diagram of compound 5 prepared in the embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation method and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable changes derived therefrom are still within the scope of protection of the claims of the present invention.

[0029] It should be noted that the endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0030] Unless otherwise defined, all terms, symbols and other scientific terms used herein are intended to have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. In some cases, terms with conventionally understood meanings are defined herein for the purpose of clarification or ease of reference, and such definitions herein should not be construed as indicating significant differences from conventional understandings in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents and instruments is carried out in accordance with the protocols and parameters given by the manufacturer.

[0031] The technical effects of the present invention are described below in conjunction with specific embodiments.

[0032] Example 1

[0033] This embodiment provides a preparation of an organic small molecule material with a structural formula of structural formula 5. The synthetic route is as follows

[0034]

[0035] The preparation method comprises:

[0036] In a 100 mL three-necked round-bottomed reaction bottle filled with argon, a mixture of 3-bromo-5-methyl-N'N-diphenylamine (6.76 g, 20.0 mmol), 2,6-difluoroaniline (3.01 g, 24.0 mmol), Pd2(dba)3 (0.18 g, 0.4 mol), t-Bu3PHBF4 (0.15 g, 1.0 mol), t-BuONa (1.44 g, 15.0 mmol) and 50 mL of toluene was stirred at 110 ° C overnight. The cooled mixture was filtered through diatomaceous earth and washed with dichloromethane. After removing the organic solvent, the remaining solid was further separated and purified by silica gel (eluted with petroleum ether / dichloromethane) chromatography to obtain pure intermediate 1, i.e., a white solid (7.01 g, yield 80%). 1 H NMR (400 MHz, CD2Cl2) δ 7.26 (dd, J = 11.2, 4.6 Hz, 4H), 7.07 (dd, J = 7.4, 6.6 Hz, 4H), 7.04–6.97 (m, 3H), 6.97–6.86 (m, 2H), 6.44 (s, 1H), 6.31 (d, J = 16.8 Hz, 2H), 5.42 (s, 1H), 2.19 (s, 3H). TOF-MS: calculated: 386.4458 measured: 387.1652.

[0037] In a 100mL three-necked round-bottomed reaction bottle filled with argon, intermediate 1 (3.86g, 10.0mmol), 2-bromobenzene-o-carborane (2.27g, 5.0mmol), Pd2(dba)3 (0.37g, 0.4mol), X-Phos (0.48g, 1.0mol), t-BuONa (2.88g, 30.0mmol) and 50mL toluene were stirred overnight at 100°C. The cooled mixture was filtered through diatomaceous earth and washed with dichloromethane. After removing the organic solvent, the remaining solid was further separated and purified by a silica gel (eluted with petroleum ether / dichloromethane) chromatographic column to obtain pure intermediate 2, i.e., a light red solid (3.21g, yield 60%). 1 H NMR (400 MHz, CD2Cl2) δ 7.21 (t, J = 7.9 Hz, 8H), 7.13 (td, J = 8.4, 4.2 Hz, 2H), 7.06–6.96 (m, 16H), 6.89 (t, J = 8.3 Hz, 4H), 6.57 (d, J = 16.4 Hz, 2H), 6.44 (dd, J = 28.9, 20.0 Hz, 8H), 3.89–2.20 (m, 10H), 2.13 (s, 6H). TOF-MS: calculated: 1065.2736 measured: 1066.5522.

[0038] In a 120mL argon-sealed pressure-resistant tube, intermediate 2 (2.02g, 2.0mmol) and 15mL dichlorobenzene (o-DCB) were added. After adding boron bromide (5.00g, 20.0mmol), the tube was sealed and then stirred at 200°C for 36h. After cooling to room temperature, ethanol (5.0mL) was slowly added under an ice bath to quench the reaction. The organic solvent was concentrated under vacuum, and the residual solid was further separated and purified by a silica gel (eluted with petroleum ether / dichloromethane) chromatographic column to obtain a pure product as a light red solid compound 5 (1.23g, yield 60%). 1 H NMR (400 MHz, CD2Cl2) δ8.93 (s, 2H), 8.47 (d, J = 7.5 Hz, 2H), 7.59 (ddd, J = 28.0, 17.7, 8.0 Hz, 10H), 7.34 (t, J = 7.2 Hz, 2H), 7.24 (d, J = 7.2 Hz, 4H), 7.17–7.01 (m, 6H), 6.67 (d, J = 8.7 Hz, 2H), 6.45 (d, J = 9.2 Hz, 2H), 6.00 (s, 2H), 5.89 (s, 2H), 2.80 (s, 10H), 2.08 (s, 6H). TOF-MS: calculated: 1082.5088 measured: 1082.5233.

[0039] The inventors tested the performance of the boron nitrogen heterocyclic compound obtained in this embodiment, and the test results are as follows: Figure 1-Figure 3 As shown, Figure 1 is the absorption and emission spectra of compound 5 prepared in the embodiment of the present invention in tetrahydrofuran solution; Figure 1 It can be seen that the emission peak of the boron nitrogen heterocyclic compound prepared in this example is located at about 450 nm, with a half-peak width of 27 nm, showing narrow-band blue light emission performance.

[0040] Figure 2 Thermogravimetric analysis and differential scanning calorimetry curves of compound 5 prepared in the embodiment of the present invention; Figure 2 It can be seen that the 5% thermal weight loss temperature of the boron nitrogen heterocyclic compound prepared in this embodiment is 495° C., the glass transition temperature is 235° C., the thermal stability is good, and it has the potential to be used as an OLED light-emitting layer.

[0041] Figure 3 is the frontier orbital distribution diagram of compound 5 obtained in the embodiment of the present invention; Figure 3 It can be seen that the triplet exciton density of the boron nitrogen heterocyclic compound prepared in this embodiment is distributed in one of the boron nitrogen fragments. Due to the spatial effect, it can isolate the intermolecular stacking and inhibit concentration quenching; its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) show a degenerate distribution feature, which is beneficial to enhance the luminescence performance.

[0042] Although the disclosure is disclosed as above, the protection scope of the disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A boron-nitrogen heterocyclic compound having a non-conjugated structure, characterized in that: The general structural formula of the boron nitrogen heterocyclic compound is as follows: Wherein, Ar1 is selected from one of an alkane having a non-conjugated structure, a cycloalkane having a non-conjugated structure, an alkene having a non-conjugated structure, an alkyne having a non-conjugated structure, and a group having a spatial configuration; Ar2 is selected from a combination of one or more of a fluorine atom, a bromine atom, a chlorine atom, a cyano group, an alkyl group, an aromatic ring composed of carbon and hydrogen atoms, and an aromatic heterocycle composed of carbon, nitrogen and hydrogen atoms; Ar3 is selected from one or more combinations of a fluorine atom, a bromine atom, a chlorine atom, a cyano group, an alkyl group, an aromatic ring composed of carbon and hydrogen atoms, and an aromatic heterocycle composed of carbon, nitrogen and hydrogen atoms.

2. The boron-nitrogen heterocyclic compound having a non-conjugated structure according to claim 1, characterized in that: The Ar1 is selected from one of Formula IV:

3. The boron-nitrogen heterocyclic compound having a non-conjugated structure according to claim 1, characterized in that: The Ar2 is selected from one of Formulas I-XII:

4. The boron-nitrogen heterocyclic compound having a non-conjugated structure according to claim 1, characterized in that: The Ar3 is selected from one of Formulas I-XII:

5. The boron-nitrogen heterocyclic compound having a non-conjugated structure according to claim 1, characterized in that: The boron nitrogen heterocyclic compound is selected from one of Formulas 1-60:

6. A method for preparing a boron-nitrogen heterocyclic compound having a non-conjugated structure as claimed in any one of claims 1 to 5, characterized in that: The preparation method specifically comprises: synthesizing a precursor containing a diborane heterocycle by a Hartwig-Buchwald reaction, and then synthesizing the precursor by a borylation reaction.

7. The method for preparing a boron-nitrogen heterocyclic compound having a non-conjugated structure according to claim 6, characterized in that: The parameters of the Hartwig-Buchwald reaction are as follows: temperature is 110° C., and time is ≥12 h.

8. The method for preparing a boron-nitrogen heterocyclic compound having a non-conjugated structure according to claim 6, characterized in that: The parameters of the borylation reaction are as follows: temperature is 200° C., and time is ≥12 h.

9. Use of the boron nitrogen heterocyclic compound according to any one of claims 1 to 5 in preparing a thermally activated delayed fluorescent material.

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