Preparation and application of an o-carborane thermally activated delayed fluorescence material

Abstract

The present invention discloses a synthesis of an o-carborane-based thermally activated delayed fluorescent material. The structure of the fluorescent material is shown in Formulas I-1 to I-4. The synthesis method is as follows: Step 1, o-carborane and 2,3,5,6-tetrafluoro-4-iodobenzonitrile are used as reaction starting materials, potassium tert-butoxide is used as a base, and dimethylformamide is used as a reaction solvent to obtain the target compound I-1. Step 2, o-carborane and 2,3,5,6-tetrafluoro-1,4-diiodobenzene are used as a base, and dimethylformamide is used as a reaction solvent to obtain the target compound I-2. Step 3, using I-2 and carbazole as starting reactants, sodium hydride as a base, and dimethylformamide as a reaction solvent to obtain the target compound I-3. Step 4, using I-3 and carbazole as starting reactants, sodium hydride as a base, and DMSO as a reaction solvent to obtain the target compound I-4. The thermally activated delayed fluorescent material provided by the present invention has structural uniqueness and novelty, and has important application value for future research and development of high luminous efficiency, thermal stability and high color purity. #imgabs0# in the formula, #imgabs1#

Description

Technical Field

[0001] The present invention belongs to the technical field of organic electroluminescent display, and relates to the preparation and potential application of an o-carborane thermally activated delayed fluorescent material. Background Art

[0002] In recent years, thermally activated delayed fluorescence (TADF) emitters have attracted worldwide attention in the field of organic light-emitting diodes (OLEDs) due to their ability to achieve nearly 100% internal quantum efficiency (IQE) through an efficient reverse crossover (RISC) process. Compared with phosphorescent complexes, TADF materials have obvious resource advantages and lower costs.

[0003] Ever since the successful synthesis of organic materials exhibiting thermally activated delayed fluorescence (TADF), TADF materials have garnered significant attention from numerous research institutions and companies both domestically and internationally. The small energy difference between the singlet and triplet states of TADF materials allows the triplet state to be upconverted to the singlet state via reverse intersystem crossing, ultimately emitting fluorescence. TADF materials offer advantages such as high internal quantum efficiency, readily available raw materials, and low production costs. They are considered third-generation luminescent materials that will significantly advance the industrialization of organic light-emitting diodes (OLEDs). The application of TADF materials in OLED devices has become a research hotspot. High-efficiency, long-life white-light OLED devices are essential for the industrialization of OLEDs, and therefore the preparation of high-efficiency white-light OLEDs based on TADF materials has become a research hotspot. This is the OLED with the highest external quantum efficiency currently available for TADF-based OLEDs.

[0004] Therefore, TADF compounds are considered to be next-generation OLED materials. Since the pioneering work on TADF, a large number of TADF emitters have been developed. To develop efficient TADF materials, two key requirements must be met: sufficient RISC flow and high ΦPL. Therefore, the design and synthesis of novel TADF molecules remains a significant challenge.

[0005] In summary, the research and development of new TADF materials for application in current OLED display technology requires high color purity and high luminous efficiency, and the development and application of new ligands are an effective way to solve this problem. Summary of the Invention

[0006] The purpose of the present invention is to synthesize a preparation method of a novel o-carborane thermally activated delayed fluorescent material and to provide a thermally activated delayed fluorescent material with potential properties.

[0007] Technical solution: The o-carborane derivatives of the present invention have the structural formula shown in formula (I-1-4).

[0008]

[0009] Furthermore, the o-carborane derivatives of the present invention are synthesized according to the following route.

[0010]

[0011] Specifically, the o-carborane derivatives of the present invention include the following steps:

[0012] Step 1: o-Carborane and 2,3,5,6-tetrafluoro-4-iodobenzonitrile are used as reaction starting materials, potassium tert-butoxide is used as a base, and dimethylformamide is used as a reaction solvent to obtain the target compound I-1.

[0013] Step 2: o-carborane and 2,3,5,6-tetrafluoro-1,4-diiodobenzene are reacted with potassium tert-butoxide as a base and dimethylformamide as a reaction solvent to obtain the target compound I-2;

[0014] Step 3, using I-2 and carbazole as starting reactants, sodium hydride as base, and dimethylformamide as reaction solvent to obtain the target compound I-3;

[0015] Step 4, using I-3 and carbazole as starting reactants, sodium hydride as a base, and DMSO as a reaction solvent, to obtain the target compound I-4.

[0016] Furthermore, the reaction temperature of step 1 of the present invention is 100° C. and the reaction time is 4 hours.

[0017] Furthermore, the reaction temperature of step 2 of the present invention is 100 degrees and the reaction time is 4 hours.

[0018] Furthermore, in step 3 of the present invention, the reaction time is 14 hours and the reaction temperature is 100°C.

[0019] Furthermore, in step 4 of the present invention, the reaction temperature is 120° C. and the reaction time is 18 hours.

[0020] Beneficial effects: The o-carborane derivatives of the present invention have potential applications as thermally activated delayed fluorescent materials.

[0021] The synthesis method of the present invention has the advantages of being safe, environmentally friendly, high in yield, and easy to operate.

[0022] Furthermore, the present invention has developed a synthetic route for simultaneously obtaining o-carborane derivatives I-1 to I-4. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the hydrogen spectrum of the compound prepared in step I-3 of Example 1

[0024] Figure 2 This is the hydrogen spectrum of the compound prepared in step I-4 of Example 1 DETAILED DESCRIPTION

[0025] To deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the following examples and accompanying drawings. These examples are intended only to illustrate the present invention and do not limit the scope of protection of the present invention. The methods described are conventional methods unless otherwise specified, and the raw materials used are available from public commercial sources unless otherwise specified.

[0026] The compounds of formula I-1 to I-4 provided by the present invention can be prepared according to the following reaction formula:

[0027]

[0028] Preparation method of Example 1I-1

[0029] 2.0 g of o-carborane, 3.6 g of 2,3,5,6-tetrafluoro-4-iodobenzocyanide, and 1.6 g of potassium tert-butoxide were weighed and dissolved in 50 mL of dimethylformamide. The mixture was added to a three-necked flask and the temperature was raised to 100°C. The reaction time was 4 hours. After the reaction was completed, the temperature was lowered to room temperature, the mixture was filtered, and the organic solvent was distilled off under reduced pressure. 20 mL of water was added to the resulting solid, which was filtered and washed to obtain 4.2 g of compound I-1 with a yield of 86%.

[0030] The test parameters are as follows: 19 F-NMR: -130.60, -138.25.

[0031] Example 2 Preparation of Compound I-2

[0032] 2.0 g of o-carborane, 4.0 g of 2,3,5,6-tetrafluoro-1,4-diiodobenzene, and 1.6 g of potassium tert-butoxide were weighed and dissolved in 50 mL of dimethylformamide. The mixture was added to a three-necked flask and the temperature was raised to 100°C. The reaction time was 4 hours. After the reaction was completed, the temperature was lowered to room temperature, the mixture was filtered, and the organic solvent was distilled off under reduced pressure. 20 mL of water was added to the resulting solid, which was filtered and washed to obtain 3.2 g of compound I-1 in a yield of 69%.

[0033] The test parameters are as follows: 19 F-NMR: -133.35, -142.65.

[0034] Preparation method of Example 3I-3

[0035] Weigh 2.0g of I-2 and 1.2g of carbazole and dissolve them in 80mL of dimethylformamide. Then add them to a three-necked flask, slowly add 0.3g (60%) of sodium hydride, raise the temperature to 100 degrees and react for 14 hours. After the reaction is complete, the temperature is lowered to room temperature. After the reaction is complete, the organic solvent is distilled under reduced pressure, 100ml of ice water is added, the generated solid is filtered, 100ml of methanol is added to the obtained solid, filtered, 100ml of acetone is added to the obtained solid again, filtered, and dried to obtain 2.0g of I-3 compound with a yield of 69%.

[0036] The test parameters are as follows:

[0037] 1 H-NMR: 7.18-7.13(m,1H), 7.42-7.40(m,1H), 7.53-7.49(m,1H), 8.18-8.15(d,J=8.17Hz,1H). 19 F-NMR: -132.31, -141.62.

[0038] Example 4 Preparation of Compound I-4

[0039] Weigh 2.0g of I-3 and 1g of carbazole, dissolve them in 80mL of DMSO, add them to a three-necked flask, slowly add 0.3g (60%) of sodium hydride, raise the temperature to 120 degrees and react for 18 hours. After the reaction is completed, the temperature is lowered to room temperature. After the reaction is completed, the organic solvent is distilled under reduced pressure, 100ml of ice water is added, the generated solid is filtered, 100ml of methanol is added to the obtained solid, filtered, 100ml of acetone is added to the obtained solid again, filtered, and dried to obtain 1.6g of I-4 compound with a yield of 61%.

[0040] The test parameters are as follows:

[0041] 1 H-NMR: 7.02-6.96(m,2H), 7.18-7.16(d,J=7.60Hz,1H), 7.28-7.25(m,1H), 7.43-7.39(m,1H), 7.65-7.58(m,2H), 8.15-8.03(d,J=8.03Hz,1H). 19 F-NMR: -134.46, -143.24.

[0042] Gaussian simulation software was used to calculate the performance parameters of the above-synthesized o-carborane compounds using time-dependent density functional theory TD-DFT. Compounds 1-4 represent I-1, I-2, I-3, and I-4, respectively. The calculation results are shown in Table 1. The performance parameters of the compounds are as follows:

[0043] Table 1

[0044]

[0045] The data show that I-1, I-2, I-3, and I-4 all have potential application characteristics of thermally activated delayed fluorescence materials.

Claims

1. An o-carborane thermally activated delayed fluorescent material, characterized in that: The fluorescent material is I-1 to 4 compound; The specific structural formula of compound I-1~2 is: Where, The specific structural formula of compound I-3~4 is: Where,

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