A new carborane derivative based on benzothiadiazole and its application in organic light-emitting diodes

Abstract

The present invention discloses a novel carborane derivative based on benzothiadiazole, which has the following structure: wherein R1-R5 are the same or different and represent one or more groups of carbazole, acridine, triphenylamine, phenothiazine, and phenoxazine at one or more positions with H; R7-R8 are the same or different and represent H, an alkyl group of C1-C4, a hydroxyl group, an amino group, or a halogen group; R8-R 11 The same or different, representing H, C1–C4 alkyl, hydroxyl, amino, or halogen groups; R 12 –R 21 The same or different groups represent H, C1–C4 alkyl, hydroxyl, amino, methoxy, or halogen groups. The present invention utilizes the unique electronic effects and stereostructure of carborane to construct a novel "V"-shaped D–A–D'–A' structure, where D and D' represent donors and A and A' represent acceptors. Due to the regulatory effect of carborane, a red light-emitting material with a maximum emission wavelength of 646 nm and a quantum yield of up to 90% was obtained. The benzothiadiazole-based carborane derivatives invented by the present invention have excellent thermal stability and have been successfully applied to organic light-emitting diodes (OLEDs), opening up a new path for the design of high-performance OLED light-emitting materials.

Description

Technical Field

[0001] The present invention belongs to the field of luminescent materials, and in particular relates to a novel carborane derivative based on benzothiadiazole and application thereof in organic light-emitting diodes. Background Art

[0002] In the process of information interaction between humans and the outside world, more than 70% of the information is transmitted through vision. Therefore, display screens, as an important medium for human-computer interaction, are widely used in various electronic products. At present, OLED display screens have been widely used in smart phones, smart watches, smart bracelets, TVs and other products. Carborane is a species rich in boron and hydrogen. Due to the presence of numerous B-H-B three-center two-electron bonds in its molecules, it has a three-dimensional aromatic structure, which also leads to its good chemical stability and thermal stability. Among them, 1,2-dicarbon-closed-dodecaborane (1,2-C2B 10 H 12 O-carborane (o-carborane) exhibits a closed icosahedral cage structure. Due to its three-center, two-electron bond and three-dimensional σ-aromaticity, it possesses unique electronic properties. Furthermore, it possesses significant steric hindrance (approximately 1 nm), excellent solubility, and inherent sublimation properties, laying the foundation for the development of optoelectronic materials and their application in OLED devices. While recent research on the application of carboranes in modulating molecular luminescence has been extensive, limited research has focused on their application in OLEDs.

[0003] In 2016, Japanese scholars Yasuda et al. first introduced carborane derivative luminescent materials into OLED devices (Angew. Chem. Int. Ed. 2016, 55 (25), 7171-7175.); in 2021, Wang Zhaojin et al. from Yancheng Institute of Technology in Jiangsu Province reported the second carborane-based OLED device (Inorg. Chem. 2021, 60 (7), 4705-4716.); in 2023, South Korean Lee et al. reported the third carborane-based OLED device (Dyes and Pigments 2023, 215, 111278). Due to the structural characteristics of carborane, these molecules all exhibit a "V"-shaped structure, but are D-A-D' type or D-A-A' type molecules. Based on the above molecules, this application creatively proposed a "V"-shaped D-A-D'-A' structure, which has not been reported yet. Compared to D–A–D' or D–A–A' carborane luminescent molecules, the D–A–D'–A' structural backbone possesses more regulatory sites, making the molecule more modifiable. Furthermore, due to the unique σ linker properties of carboranes, charge transfer and radiative transitions are possible between the multiple D / A combinations contained within the molecule. The luminescence spectrum of D–A–D' or D–A–A' molecules is typically around 80nm wide at half maximum (FWHM). This high FWHM reduces the color purity of the molecules, hindering their applications in displays. Furthermore, when used as a formulation component in white light-emitting materials, the narrow FWHM affects the color temperature of the materials. The "V"-shaped D–A–D'–A' structure exhibits a larger FWHM due to the coexistence of multiple radiative transitions, opening up new avenues for the design of white-light-emitting OLEDs. Summary of the Invention

[0004] In response to the deficiencies in the prior art, the present invention provides a class of novel carborane derivatives based on benzothiadiazole, which emit orange-red or red light, have high quantum yield, and have the advantages of simple synthesis, high thermal stability, and excellent luminescent properties.

[0005] The specific technical solutions of the present invention are as follows:

[0006] A new carborane derivative based on benzothiadiazole has the following structure: Wherein, R1-R5 are the same or different and represent H, substituted by H, C1-C4 alkyl, hydroxyl, amino or halogen groups or more. R6–R7 are the same or different and represent H, C1–C4 alkyl, hydroxyl, amino or halogen groups; R8–R 11 are the same or different, representing H, C1–C4 alkyl, hydroxyl, amino or halogen groups; R 12–R 21 are the same or different and represent H, C1-C4 alkyl, hydroxy, amino, C1-C4 alkoxy or halogen.

[0007] Preferably, R1-R5 are the same or different and represent H, substituted by H, C1-C4 alkyl, hydroxyl, amino or halogen groups or more. R7-R8 are the same or different and represent one or more of H, C1-C4 alkyl (preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl), hydroxyl, amino, F, Cl, Br, I; R8-R 11 are the same or different and represent one or more of H, C1-C4 alkyl (preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl), hydroxyl, amino, F, Cl, Br, and I groups; R 12 –R 21 The same or different, representing one or more of H, C1-C4 alkyl (preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl), amino, methoxy, F, Cl, Br, I groups.

[0008] Preferably, the novel benzothiadiazole-based carborane derivative of the present invention has the following structure:

[0009]

[0010] The compound of the present invention can be prepared by adopting the method of synthesizing carborane by alkyne insertion method.

[0011] Taking the molecule with a carbazole group at the R3 position as an example, the reaction formula is as follows:

[0012]

[0013] Wherein R3 is a carbazole group.

[0014] In the above preparation method, all solvents were dried over Na, refluxed, and redistilled before use, and all reactions were carried out under anhydrous and oxygen-free conditions. The resulting product was extracted, dried, and concentrated, then purified by column chromatography using 200–300 mesh silica gel and vacuum-dried for 12 hours to obtain the final product.

[0015] Another object of the present invention is to provide the use of the novel benzothiadiazole-based carborane derivatives described herein in the preparation of optoelectronic materials. These optoelectronic materials are orange-red or red luminescent materials with a maximum emission wavelength above 580 nm. The benzothiadiazole-based carborane derivatives described herein can be used to prepare organic light-emitting diode (OLED) devices, particularly the light-emitting layer of these devices.

[0016] The carborane in the compound structure described in this invention possesses unique three-dimensional aromaticity, enabling effective manipulation of the molecule's luminescence color and efficiency. Furthermore, due to the carborane's unique three-dimensional structure, a novel "V"-shaped D–A–D'–A' structure is formed. The A' group also effectively modulates the molecule's charge transfer pattern and photophysical properties.

[0017] Advantages of the present invention:

[0018] 1. This invention utilizes the unique electronic effects and steric structure of carborane to construct a novel "V"-shaped D–A–D'–A' structure. Due to the regulatory effect of carborane, a red-emitting material with a maximum emission wavelength of 646 nm is obtained, with a quantum yield of up to 90%. Furthermore, due to the carborane's control over the electron transfer mode, the resulting molecule exhibits a full width at half maximum (FWHM) of up to 174 nm.

[0019] 2. The benzothiadiazole-based carborane derivatives invented by the present invention have good thermal stability and have been successfully applied to organic light-emitting diodes (OLEDs), opening up a new path for the design of high-performance OLED light-emitting materials.

[0020] 3. The carborane derivatives designed in the present invention have novel structures, simple and efficient synthesis, and are suitable for industrial production and commercial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The crystal structure of the carborane derivative of the present invention.

[0022] Figure 2 This is the solid-state luminescence spectrum of the carborane derivatives described in the present invention.

[0023] Figure 3 This is the solid-state excited state lifetime curve of the carborane derivative described in the present invention.

[0024] Figure 4 The emission spectrum of an OLED device prepared by using the carborane derivative of the present invention as a light-emitting layer.

[0025] Figure 5is the CIE (Commission Internationale de L'Eclairage) coordinate of an OLED device prepared by using the carborane derivative of the present invention as a light-emitting layer.

[0026] Figure 6 The figure shows the relationship between brightness and external quantum efficiency of an OLED device prepared by using the carborane derivatives of the present invention as a light-emitting layer. DETAILED DESCRIPTION

[0027] The specific steps of the present invention are described below by way of examples, but are not limited to the examples.

[0028] Unless otherwise specified, the terms used in the present invention generally have the meanings commonly understood by those skilled in the art.

[0029] The present invention will be described in further detail below in conjunction with specific examples and with reference to data. It should be understood that these embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention in any way.

[0030] In the following examples, various processes and methods not described in detail are conventional methods known to those of ordinary skill in the art.

[0031] Example 1

[0032]

[0033] Step 1: Preparation of N,N-diphenyl-4-(7-(phenylethynyl)-4-benzo[1,2,5]thiadiazole)aniline: Under argon protection, 23.0 g (50.2 mmol) of 4-(7-bromo-4-benzo[1,2,5]thiadiazole-yl)-N,N-diphenylamine, 3.0 g (2.5 mmol) of tetrakistriphenylphosphine palladium, 0.9 g (5 mmol) of cuprous iodide, 25.5 g (250 mmol) of phenylacetylene, and 500 mL of anhydrous tetrahydrofuran:triethylamine (1:1) were added to a reaction vessel. The mixture was refluxed for 24 h and then cooled to room temperature. After extraction, the mixture was concentrated by rotary evaporation and purified by 200-300 mesh silica gel column chromatography. The mixture was dried in vacuo to obtain red powder PhABT.

[0034] Step 2: Preparation of compound 1: Under argon atmosphere, add the above red powder PhABT9.5g (20mmol), decaborane acetonitrile complex (B 10 H 12 The mixture was refluxed for 24 hours, cooled to room temperature, extracted, concentrated by rotary evaporation, purified by 200-300 mesh silica gel column chromatography, and dried in vacuo to obtain compound 1 as a red powder.1 H NMR (400MHz, CD2Cl2): δ = 7.77 (d, J = 7.8Hz, 1H), 7.69–7.60 (m, 2H), 7.40–7. 30(m,3H),7.24–7.15(m,4H),7.14–6.87(m,11H),4.20–1.47(br,10H,B–H); 13 C NMR (101MHz, CD2Cl2): δ=154.24,153.98,149.26,147.57,136.97,135.44,131.21,130.98 ,130.61,129.81,129.57,128.72,125.65,125.55,124.13,122.33,120.93,87.83,83.75; 11 B NMR (128MHz, CD2Cl2): δ = -1.54 (1B), -3.19 (1B), -10.15 (8B). HR-MS (ESI) m / z: 597.3217[M] + calculated for C 32 H 31 B 10 N3S 597.3236.mp:163.3–163.9℃.IR:(νcm -1 )2693(B–H).

[0035] Example 2

[0036]

[0037] Referring to the method described in Example 1, 4-(7-bromo-4-benzo[1,2,5]thiadiazol-yl)-N,N-diphenylamine was reacted with 9-(4-ethynylphenyl)carbazole to obtain 4-(7-((4-(9H-carbazole-9-yl)phenyl)ethynyl)4-benzo[1,2,5]thiadiazol)-N,N-diphenylaniline, which was then reacted with decaborane-acetonitrile intermediate to obtain red powder compound 2. 1 H NMR (400MHz, CDCl3) δ=8.10–8.02(m,2H),7.88(d,J=7.8Hz,1H),7.81–7.75(m,2H),7.64–7.58(m,2H),7. 49(d,J=7.8Hz,1H),7.32–7.20(m,10H),7.20–7.12(m,6H),7.12–7.03(m,4H),4.47–1.89(br,10H,B–H). 13C NMR(101MHz, CDCl3)δ=153.99,153.60,148.99,147.14,140.04,139.53,136.91,134.94,132.14,130.23,129.66, 129.46,129.07,126.25,126.07,125.18,123.76,123.60,122.26,120.65,120.44,120.39,109.36,86.32,83.21. 11 B NMR (128MHz, CDCl3): δ = -2.81 (2B), -10.65 (8B). HR-MS (ESI) m / z: 763.3898 [M] + calculated for C 44 H 38 B 10 N4S 763.3893.mp:172.8–173.5℃.IR:(νcm -1 )2660(B–H).

[0038] Example 3

[0039]

[0040] Referring to the method described in Example 1, 4-(7-bromo-4-benzo[1,2,5]thiadiazol-yl)-N,N-diphenylamine was reacted with 9-(3-ethynylphenyl)carbazole to obtain 4-(7-((3-(9H-carbazole-9-yl)phenyl)ethynyl)4-benzo[1,2,5]thiadiazol)-N,N-diphenylaniline, which was then reacted with decaborane-acetonitrile intermediate to obtain red powder compound 3. 1 H NMR (400MHz, CDCl3) δ=8.11–8.05(m,2H),7.96(d,J=7.8Hz,1H),7.80–7.73(m,2H),7.62(m,2H),7.51(d,J=7.8Hz,1H),7.41–7.34 (m,2H),7.33–7.27(m,4H),7.27–7.20(m,4H),7.19–7.12(m,6H),7.12–7.06(m,2H),6.78–6.70(m,2H),4.37–1.80(br,10H,B–H). 13C NMR(101MHz, CDCl3)δ=153.82,153.62,148.99,147.11,140.33,137.71,136.99,135.07,133.02,130.22,129.93,129.82, 129.46,129.24,128.98,128.88,126.09,125.24,123.79,123.41,122.12,120.66,120.43,120.31,108.81,85.86,83.15. 11 B NMR (128MHz, CDCl3): δ = -2.31 (2B), -10.17 (8B). HR-MS (ESI) m / z: 763.3889 [M] + calculated for C 44 H 38 B 10 N4S763.3893.mp:178.8–179.7℃.IR:(νcm -1 )2722(B–H).

[0041] Example 4

[0042]

[0043] Referring to the method described in Example 1, 4-(7-bromo-4-benzo[1,2,5]thiadiazol-yl)-N,N-diphenylamine was reacted with 9,9-dimethyl-10-(4-bromophenyl)-9,10-dihydroacridine to obtain 4-(7-((9,9-dimethyl-10-(4-bromophenyl)-9,10-dihydroacridine)ethynyl)-4-benzo[1,2,5]thiadiazol)-N,N-diphenylaniline, which was then reacted with decaborane-acetonitrile intermediate to obtain red powder compound 4. 1 H NMR (400MHz, CDCl3) δ = 7.88 (d, J = 7.8Hz, 1H), 7.82–7.76 (m, 2H), 7.69–7.62 (m, 2H), 7.5 1(d,J=7.8Hz,1H),7.37(dd,J=7.8,1.5Hz,2H),7.34–7.27(m,4H),7.21–7.13(m,6H),7 .12–7.06(m,2H),7.03–6.97(m,2H),6.83(ddd,J=8.6,7.5,1.2Hz,2H),6.66(ddd,J=8. 6,7.3,1.5Hz,2H),5.67(dd,J=8.2,1.2Hz,2H),4.52–1.72(br,10H,B–H),1.58(s,6H). 13C NMR(101MHz, CDCl3)δ=153.89,153.49,149.01,147.17,143.19,140.14,136.85,134.93,133.24,131.02,130.75,130.24 ,129.46,129.10,126.29,125.28,125.11,124.97,123.72,122.40,120.89,120.57,113.57,86.22,83.06,35.90,31.07. 11 B NMR (128MHz, CDCl3): δ = -2.42 (2B), -9.72 (8B). HR-MS (ESI) m / z: 805.4287 [M] + calculated for C 47 H 45 B 10 N4S 805.4363.mp:171.4–172.1℃.IR:(νcm -1 )2687(B–H).

[0044] Example 5

[0045]

[0046] Referring to the method described in Example 1, 4-(7-bromo-4-benzo[1,2,5]thiadiazol-yl)-N,N-diphenylamine was reacted with 9-(4-ethynylphenyl)phenoxazine to obtain 4-(7-((4-(9H-phenoxazin-9-yl)phenyl)ethynyl)4-benzo[1,2,5]thiadiazol)-N,N-diphenylaniline, which was then reacted with decaborane-acetonitrile intermediate to obtain red powder compound 5. 1 H NMR (400MHz, CDCl3) δ = 7.85 (d, J = 7.9Hz, 1H), 7.81–7.74 (m, 2H), 7.61 (dd, J = 8.5,1.5Hz,2H),7.47(d,J=7.8Hz,1H),7.34–7.26(m,4H),7.21–7.12(m,6H) ,7.12–7.06(m,2H),7.04–6.98(m,2H),6.68–6.51(m,4H),6.30(ddd,J=7.8, 7.8,1.8Hz,2H),5.37(ddd,J=8.0,7.8,1.3Hz,2H),4.16–1.68(br,10H,B–H). 13C NMR(101MHz, CDCl3)δ=153.87,153.45,149.02,147.12,143.77,140.93,136.86,134.88,133.40,131.07,130.66, 130.19,129.47,128.97,125.14,124.88,123.77,123.15,122.31,121.69,120.47,115.61,112.78,85.97,83.04. 11 BNMR (128MHz, CDCl3): δ = -2.00 (2B), -10.08 (8B). HR-MS (ESI) m / z: 779.3859[M] + calculated for C 44 H 39 B 10 N4SO 779.3842.mp:173.9–175.0℃.IR:(νcm -1 )2703(B–H).

[0047] Example 6

[0048] The crystal diffraction data of compounds 1–5 were collected using a CCD-Bruker Smart APEX 11. The structures were solved using the OLEX 2 program integrated with Shelx, and the ball-and-stick model was drawn using Diamond software. Figure 1 Crystal structure diagrams of compounds 1–5 are shown.

[0049] The luminescence spectra of compounds 1–5 were measured using a HORIBA FL-3 transient and steady-state fluorescence spectrometer equipped with an integrating sphere ( Figure 2 ), excited state lifetime curve ( Figure 3 ) and absolute quantum yield, the above photophysical properties are shown in Table 1.

[0050] Table 1 Photophysical properties of compounds 1–5

[0051]

[0052] Example 7

[0053] OLED devices were prepared by vacuum evaporation, wherein compound 2 and 4,4'-bis(9-carbazole)biphenyl (CBP) were used as guest materials in the light-emitting layer. In this example, five OLED devices were prepared using five different doping ratios of compound 2. The emission spectra of the five OLED devices are shown in Figure 2. Figure 4As shown, CIE (Commission Internationale de L'Eclairage) coordinates are as follows Figure 5 As shown in the figure, the relationship between brightness and external quantum efficiency is as follows Figure 6 The results show that compound 2 is suitable for OLED light-emitting materials.

Claims

1. A carborane derivative based on benzothiadiazole, characterized in that Has the following structure: , wherein R1-R5 are the same or different, represent H, substituted by one or more of H, C1-C4 alkyl, hydroxyl, amino or halogen groups 、 、 、 or ; R6-R7 are the same or different and represent H, C1-C4 alkyl, hydroxyl, amino or halogen groups; R8-R 11 The same or different, representing H, C1-C4 alkyl, hydroxyl, amino, halogen group; R 12 –R 21 are the same or different and represent H, C1-C4 alkyl, hydroxy, amino, C1-C4 alkoxy or halogen.

2. The benzothiadiazole-based carborane derivative according to claim 1, characterized in that R6-R7 are the same or different and represent one or more of H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, hydroxyl, amino, F, Cl, Br, and I groups; R8-R 11 are the same or different, representing one or more of H, C1-C4 alkyl, hydroxyl, amino, F, Cl, Br, and I groups; R 12 -R 21 The same or different, representing one or more of H, C1-C4 alkyl, hydroxyl, amino, methoxy, F, Cl, Br, and I groups.

3. The benzothiadiazole-based carborane derivative according to claim 1, characterized in that The following structure: or or or or or .

4. Use of the benzothiadiazole-based carborane derivative according to any one of claims 1 to 3 in the preparation of optoelectronic materials.

5. The use according to claim 4, characterized in that The photoelectric material is an orange-red or red light emitting material.

6. The use according to claim 5, characterized in that The maximum emission wavelength of the photoelectric material is above 580 nm.

7. The use according to claim 4, characterized in that The benzothiadiazole-based carborane derivative is used for preparing an OLED device.

8. The use according to claim 4, characterized in that The benzothiadiazole-based carborane derivative is used to prepare the light-emitting layer of an OLED device.

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