Boron-containing compound, light-emitting material, and light-emitting device using the same

Abstract

The present invention provides a compound represented by formula (I) (wherein X, Y, and Z are each independently a hydrogen atom or an (un)substituted nitrogen-containing heteroaryl group but Y and / or Z is an (un)substituted nitrogen-containing heteroaryl group).

Description

[Technical field]

[0001] The present invention relates to a boron-containing compound, a light-emitting material, and a light-emitting device using the same. More specifically, the present invention relates to a boron-containing compound having excellent light-emitting properties, a light-emitting material, and a light-emitting device using the same. [Background technology]

[0002] For example, Patent Documents 1 to 4 propose various compounds having a nitrogen-containing condensed ring structure as light-emitting materials. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO 2015 / 102118 A [Patent Document 2] CN 107501311A [Patent Document 3] CN 110407858A [Patent Document 4] JP 2012-234873 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a novel boron-containing compound having excellent light-emitting properties, a light-emitting material, and a light-emitting device using the same. [Means for solving the problem]

[0005] As a result of intensive research aimed at solving the above problems, the present invention has been completed, which includes the following aspects.

[0006] That is, the present invention is as follows. [1] A compound represented by formula (I):

[0007] [ka] In formula (I), X, Y, and Z each independently represent a hydrogen atom or a substituted or unsubstituted nitrogen-containing heteroaryl group, provided that at least one of Y and Z is a substituted or unsubstituted nitrogen-containing heteroaryl group.

[0008] [2] The compound according to [1], wherein at least one of Y and Z is a substituted or unsubstituted 9-carbazolyl group. [3] The compound according to [1], wherein at least one of Y and Z is a C1-4 alkyl-substituted 9-carbazolyl group. [4] The compound according to [1], wherein at least one of Y and Z is a 3,6-di-t-butyl-9-carbazolyl group.

[0009] [5] A light-emitting material comprising the compound according to any one of [1] to [4].

[0010] [6] A light-emitting device containing the light-emitting material according to [5]. Effect of the Invention

[0011] The boron-containing compound of the present invention is useful as a light-emitting material. The light-emitting material of the present invention may emit delayed fluorescence. A light-emitting device containing the light-emitting material of the present invention may achieve excellent light-emitting efficiency. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a diagram showing the PL spectrum of the toluene solution produced in Example 1. [Diagram 2] FIG. 2 is a diagram showing the absorption and emission spectra of the toluene solution prepared in Example 1. [Diagram 3] FIG. 2 is a diagram showing the absorption and emission spectra of the toluene solution prepared in Example 1. [Figure 4] FIG. 2 is a diagram showing the absorption and emission spectra of the toluene solution prepared in Example 1. [Diagram 5]FIG. 2 is a diagram showing the absorption and emission spectra of the toluene solution prepared in Example 1. [Figure 6] FIG. 2 shows the transient PL intensity of the toluene solution produced in Example 1. [Figure 7] FIG. 2 is a diagram showing an energy diagram of the organic electroluminescence element produced in Example 2. [Figure 8] FIG. 13 is a diagram showing the Lambertian distribution of the organic electroluminescence element produced in Example 2. [Figure 9] FIG. 1 is a graph showing the current density-external quantum efficiency characteristics of the organic electroluminescence device produced in Example 2. [Figure 10] FIG. 4 is a diagram showing the voltage-current density characteristics of the organic electroluminescence element produced in Example 2. [Figure 11] FIG. 2 is a diagram showing the PL spectrum of the organic electroluminescence device produced in Example 2. [Figure 12] FIG. 1 shows the PL spectrum of the toluene solution prepared in Example 3. [Figure 13] FIG. 1 shows the absorption and emission spectra of the toluene solution prepared in Example 3. [Figure 14] FIG. 13 shows the transient PL intensity of the toluene solution produced in Example 3. [Figure 15] FIG. 13 is a diagram showing the Lambertian distribution of the organic electroluminescence element produced in Example 4. [Figure 16] FIG. 10 is a graph showing the current density-external quantum efficiency characteristics of the organic electroluminescence device produced in Example 4. [Figure 17] FIG. 10 is a diagram showing the voltage-current density characteristics of the organic electroluminescence element produced in Example 4. [Figure 18] FIG. 13 is a diagram showing the PL spectrum of the organic electroluminescence device produced in Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The boron-containing compound of the present invention is a compound represented by formula (I).

[0014] [ka] In formula (I), X, Y, and Z each independently represent a hydrogen atom or a substituted or unsubstituted nitrogen-containing heteroaryl group, provided that at least one of Y and Z is a substituted or unsubstituted nitrogen-containing heteroaryl group.

[0015] The nitrogen-containing heteroaryl group in X, Y, and Z may be either a single ring or a polycyclic ring. As long as at least one ring of the nitrogen-containing polycyclic heteroaryl group is a nitrogen-containing heteroaromatic ring, the remaining rings may be any of saturated rings, unsaturated rings, or aromatic rings, but the remaining rings are preferably aromatic rings. The number of atoms constituting the unsubstituted nitrogen-containing heteroaryl group is preferably 5 to 40, more preferably 5 to 20, and even more preferably 5 to 14. Examples of unsubstituted nitrogen-containing heteroaryl groups include 5-membered ring heteroaryl groups such as an imidazolyl group, a pyrazolyl group, a triazolyl group, an oxadiazolyl group, a thiadiazolyl group, and a tetrazolyl group; 6-membered ring heteroaryl groups such as a pyridyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, and a triazinyl group; and fused ring heteroaryl groups such as an indolyl group, a benzimidazolyl group, a quinolyl group, an isoquinolyl group, a quinoxalinyl group, and a carbazolyl group.

[0016] The substituents on the substituted nitrogen-containing heteroaryl group are not particularly limited as long as they are chemically permissible and have the effect of the present invention. Specific examples of groups which can be "substituents" include the following groups. halogeno groups such as fluoro, chloro, bromo, and iodo groups; C1-6 alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, i-butyl, t-butyl, n-pentyl, and n-hexyl groups; C2-6 alkenyl groups such as vinyl group, 1-propenyl group, 2-propenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-methyl-2-propenyl group, 2-methyl-2-propenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, 1-methyl-2-butenyl group, 2-methyl-2-butenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 4-hexenyl group, and 5-hexenyl group;

[0017] C2-6 alkynyl groups such as ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-methyl-2-propynyl, 2-methyl-3-butynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 1-methyl-2-butynyl, 2-methyl-3-pentynyl, 1-hexynyl, and 1,1-dimethyl-2-butynyl; C3-8 cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cubanyl; C3-8 cycloalkenyl groups, such as a 2-cyclopropenyl group, a 2-cyclopentenyl group, a 3-cyclohexenyl group, or a 4-cyclooctenyl group; C6-10 aryl groups such as phenyl and naphthyl groups; 5-membered heteroaryl groups such as a pyrrolyl group, a furyl group, a thienyl group, an imidazolyl group, a pyrazolyl group, an oxazolyl group, an isoxazolyl group, a thiazolyl group, an isothiazolyl group, a triazolyl group, an oxadiazolyl group, a thiadiazolyl group, and a tetrazolyl group; 6-membered heteroaryl groups such as a pyridyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, and a triazinyl group; fused-ring heteroaryl groups such as indolyl, benzofuryl, benzothienyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, quinolyl, isoquinolyl, and quinoxalinyl groups; cyclic ether groups such as an oxiranyl group, a tetrahydrofuryl group, a dioxolanyl group, and a dioxanyl group; cyclic amino groups such as an aziridinyl group, a pyrrolidinyl group, a piperidyl group, a piperazinyl group, or a morpholinyl group;

[0018] Hydroxyl group; Oxo group; C1-6 alkoxy groups, such as a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an s-butoxy group, an i-butoxy group, or a t-butoxy group; C2-6 alkenyloxy groups such as a vinyloxy group, an allyloxy group, a propenyloxy group, or a butenyloxy group; C2-6 alkynyloxy groups such as ethynyloxy groups and propargyloxy groups; C6-10 aryloxy groups such as phenoxy and naphthoxy groups; 5- to 6-membered heteroaryloxy groups, such as thiazolyloxy groups and pyridyloxy groups;

[0019] Carboxyl group; Formyl group; C1-6 alkylcarbonyl groups such as acetyl group and propionyl group; formyloxy group; C1-6 alkylcarbonyloxy group such as acetyloxy group and propionyloxy group; C1-6 alkoxycarbonyl groups, such as a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an i-propoxycarbonyl group, an n-butoxycarbonyl group, or a t-butoxycarbonyl group;

[0020] C1-6 haloalkyl groups such as a chloromethyl group, a chloroethyl group, a trifluoromethyl group, a 1,2-dichloro-n-propyl group, a 1-fluoro-n-butyl group, and a perfluoro-n-pentyl group; C2-6 haloalkenyl groups, such as a 2-chloro-1-propenyl group and a 2-fluoro-1-butenyl group; C2-6 haloalkynyl groups such as a 4,4-dichloro-1-butynyl group, a 4-fluoro-1-pentynyl group, and a 5-bromo-2-pentynyl group; C3-6 halocycloalkyl groups such as a 3,3-difluorocyclobutyl group; C1-6 haloalkoxy groups, such as a 2-chloro-n-propoxy group, a 2,3-dichlorobutoxy group, a trifluoromethoxy group, and a 2,2,2-trifluoroethoxy group; C2-6 haloalkenyloxy groups, such as a 2-chloropropenyloxy group or a 3-bromobutenyloxy group; C1-6 haloalkylcarbonyl groups such as a chloroacetyl group, a trifluoroacetyl group, or a trichloroacetyl group;

[0021] Cyano group; Nitro group; Amino group; C1-6 alkylamino groups such as methylamino, dimethylamino, and diethylamino groups; C6-10 arylamino groups such as anilino group and naphthylamino group; formylamino group; C1-6 alkylcarbonylamino group such as acetylamino group, propanoylamino group, butyrylamino group, and i-propylcarbonylamino group; C1-6 alkoxycarbonylamino groups, such as a methoxycarbonylamino group, an ethoxycarbonylamino group, an n-propoxycarbonylamino group, or an i-propoxycarbonylamino group; C1-6 alkylsulfoximino groups such as S,S-dimethylsulfoximino groups;

[0022] Aminocarbonyl group; C1-6 alkylaminocarbonyl groups, such as a methylaminocarbonyl group, a dimethylaminocarbonyl group, an ethylaminocarbonyl group, or an i-propylaminocarbonyl group; imino C1-6 alkyl group such as an iminomethyl group, a (1-imino)ethyl group, or a (1-imino)-n-propyl group; hydroxyimino C1-6 alkyl groups such as a hydroxyiminomethyl group, a (1-hydroxyimino)ethyl group, or a (1-hydroxyimino)propyl group; C1-6 alkoxyimino C1-6 alkyl groups such as a methoxyiminomethyl group and a (1-methoxyimino)ethyl group;

[0023] Mercapto group; C1-6 alkylthio groups, such as a methylthio group, an ethylthio group, an n-propylthio group, an i-propylthio group, an n-butylthio group, an i-butylthio group, an s-butylthio group, or a t-butylthio group; C1-6 haloalkylthio groups, such as a trifluoromethylthio group and a 2,2,2-trifluoroethylthio group; C2-6 alkenylthio groups such as vinylthio groups and allylthio groups; C2-6 alkynylthio groups, such as an ethynylthio group or a propargylthio group; C1-6 alkylsulfinyl groups such as a methylsulfinyl group, an ethylsulfinyl group, or a t-butylsulfinyl group; C1-6 haloalkylsulfinyl groups such as a trifluoromethylsulfinyl group and a 2,2,2-trifluoroethylsulfinyl group; C2-6 alkenylsulfinyl groups, such as an allylsulfinyl group; C2-6 alkynylsulfinyl groups, such as a propargylsulfinyl group; C1-6 alkylsulfonyl groups such as a methylsulfonyl group, an ethylsulfonyl group, or a t-butylsulfonyl group; C1-6 haloalkylsulfonyl groups such as a trifluoromethylsulfonyl group or a 2,2,2-trifluoroethylsulfonyl group; C2-6 alkenylsulfonyl groups, such as an allylsulfonyl group; C2-6 alkynylsulfonyl groups, such as a propargylsulfonyl group;

[0024] Tri-C1-6 alkylsilyl groups such as trimethylsilyl group, triethylsilyl group, and t-butyldimethylsilyl group; Tri-C6-10 arylsilyl groups, such as triphenylsilyl groups; In addition, any hydrogen atom in these "substituents" may be substituted with a group having a different structure.

[0025] Terms such as "C1-6" indicate that the number of carbon atoms in the core group is 1-6. This number of carbon atoms does not include the number of carbon atoms in the substituent. For example, an ethoxybutyl group is classified as a C2 alkoxyC4 alkyl group because the core group is a butyl group and the substituent is an ethoxy group.

[0026] R is preferably a hydroxy group, a halogeno group, a C1-20 alkyl group, a C1-20 alkoxy group, a C1-20 alkylthio group, a C1-20 alkyl-substituted amino group, a C6-40 aryl-substituted amino group, a C6-40 aryl group, a 5-40-membered heteroaryl group, a C2-10 alkenyl group, a C2-10 alkynyl group, a C2-20 alkylamido group, a C6-20 arylamido group, or a tri-C1-10 alkylsilyl group, and more preferably a C1-20 alkyl group, a C1-20 alkoxy group, a C1-20 alkylthio group, a C1-20 alkyl-substituted amino group, a C6-40 aryl-substituted amino group, a C6-40 aryl group, or a 5-40-membered heteroaryl group.

[0027] Examples of a ring formed by connecting two adjacent Rs include a benzene ring, a naphthalene ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a pyrrole ring, an imidazole ring, a pyrazole ring, an imidazoline ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, a cyclohexadiene ring, a cyclohexene ring, a cyclopentene ring, a cycloheptatriene ring, a cycloheptadiene ring, and a cycloheptene ring.

[0028] Specific examples of the boron-containing compound of the present invention include the following: However, these are merely examples, and the present invention is not limited to these exemplified compounds.

[0029] [ka]

[0030] [ka]

[0031] [ka]

[0032] The boron-containing compound of the present invention can be obtained by combining known synthesis reactions (for example, coupling reactions, substitution reactions, etc.).

[0033] For example, the compound represented by formula (I) can be obtained as follows.

[0034] (Synthesis Example 1) (Synthesis of 2BCz-BCB) [ka]

[0035] In a 300mL Schlenk flask, t-BuOK (1.513g, 13.5mmol), dehydrated DMF (100ml), and 3,6-di-t-butyl-carbazole (3.766g, 13.5mmol) were added and stirred at room temperature for 30 minutes. Then, 1-bromo-2,3,5,6-tetrafluorobenzene (0.686g, 3.00mmol) was added and refluxed for 24 hours. The resulting liquid was poured into water, and dichloromethane was added to perform extraction. Magnesium sulfate was added to the resulting organic layer to dry it, and it was filtered and concentrated with a rotary evaporator. The concentrated product was recrystallized with chloroform and methanol to obtain 1.76g (yield 46.0%) of white crystals of 4BCz-Br. 1 H-NMR (400MHz, CDCl 3 ,δ): 8.20 (s, 1H), 7.64 (d, J = 2.0 Hz, 4H), 7.63 (d, J = 1.8 Hz, 4H) 7.10-7.02 (m, 16H), 1.40 (s, 36H), 1.39 (s, 36H).

[0036] In a 300 ml Schlenk flask, 4BCz-Br (2.528 g, 2.00 mmol) and dehydrated t-butylbenzene (150 ml) were added. After nitrogen replacement, n-butyllithium (1.9 mL, 1.6 M, 3.00 mmol) was added little by little at 0°C and stirred at room temperature for 4 hours. Then, boron tribromide (0.29 mL, 3.00 mmol) was added little by little at 0°C and stirred at room temperature overnight. Then, N,N-diisopropylethylamine (0.5 mL, 3.0 mmol) was added at 0°C and stirred at 180°C for 24 hours. The obtained liquid was returned to room temperature, poured into water, and extracted with chloroform. The obtained organic layer was filtered, and the filtrate was washed with water, dried by adding magnesium sulfate, and concentrated with a rotary evaporator. The concentrated product was separated by silica gel column chromatography (n-hexane / chloroform=9 / 1) to obtain 0.35 g (yield 14.6%) of orange crystals of 2BCz-BCB. 1 H-NMR (400MHz, CDCl 3 ,δ): 9.18 (d, J = 1.8 Hz, 2H), 8.32 (d, J = 1.5 Hz, 2H), 8.21 (s, 1H), 7.86 (d, J = 1.5 Hz, 4H), 7.66 (d, J = 1.6 Hz, 2H), 7.22 (br s, 4H),7.02 (br s, 4H), 6.68 (d, J = 8.8 Hz, 2H), 6.27 (dd, J = 8.8, 2.0 Hz, 2H), 1.68(s, 18H), 1.35 (s, 36H), 1.14 (s, 18H).

[0037] (Synthesis Example 2) (Synthesis of 3BCz-BCB) [ka]

[0038] In a 300mL Schlenk flask, t-BuOK (1.233 g, 11.0 mmol), dehydrated DMF (120 ml), and 3,6-di-t-butyl-carbazole (3.069 g, 11.0 mmol) were added and stirred at room temperature for 30 minutes. Iodopentafluorobenzene (0.586 g, 2.00 mmol) was then added and refluxed for 24 hours. The resulting liquid was poured into water, and dichloromethane was added for extraction. The organic layer was dried with magnesium sulfate, filtered, and concentrated using a rotary evaporator. The residue was recrystallized from chloroform and methanol to obtain 2.26 g of white crystals of 5BCz-I (yield 71.0%). 1 H-NMR (400MHz, CDCl 3 ,δ): 7.60 (d, J = 1.5 Hz, 4H), 7.18 (dd, J = 4.8, 1.8 Hz, 8H), 7.02 (dd, J = 8.7, 1.9 Hz, 4H), 6.93 (d, J = 8.8 Hz, 4H), 6.81 (d, J = 8.8 Hz, 4H), 6.68 (dd, J = 8.8, 2.0 Hz, 2H), 6.58 (dd, J = 8.8, 2.0 Hz, 4H), 1.35 (s,36H), 1.22 (s, 36H), 1.11 (s, 18H)

[0039] In a 300 ml Schlenk flask, 5BCz-I (3.178 g, 2.00 mmol) and dehydrated t-butylbenzene (150 mL) were added. After nitrogen replacement, n-butyllithium (1.9 mL, 1.6 M, 3.00 mmol) was added little by little at 0°C and stirred at room temperature for 4 hours. Then, boron tribromide (0.29 mL, 3.00 mmol) was added little by little at 0°C and stirred at room temperature overnight. Then, N,N-diisopropylethylamine (0.5 mL, 3.00 mmol) was added at 0°C and stirred at 180°C for 24 hours. The obtained liquid was returned to room temperature, poured into water, and extracted with chloroform. The obtained organic layer was filtered, and the filtrate was washed with water, dried by adding magnesium sulfate, and concentrated with a rotary evaporator. The concentrated product was separated by silica gel column chromatography (n-hexane / chloroform=9 / 1) to obtain 0.68 g (yield 23.2%) of yellow crystals of 3BCz-BCB. 1 H-NMR (400MHz, CDCl 3 ,δ):δ 8.81 (d, J = 1.8 Hz, 2H), 8.38 (d, J = 1.8 Hz, 2H),7.73 (d, J = 2.0 Hz, 2H), 7.37 (d, J = 1.8 Hz, 4H), 7.25 (d, J = 9.0 Hz, 2H), 7.20 (d, J = 1.8 Hz, 2H), 6.56 (dd, J = 8.5, 1.8 Hz, 4H), 6.46 (d, J = 8.5 Hz, 4H), 6.35 (dd, J = 8.7, 1.9 Hz, 2H), 6.13 (dd, J = 8.9, 2.1 Hz, 2H), 5.87 (d, J = 8.8 Hz, 2H), 1.71 (s, 18H), 1.26 (s, 18H), 1.23 (s, 36H), 1.11 (s, 18H).

[0040] (Synthesis Example 3) (Synthesis of BC2B) [ka]

[0041] In a 200mL Schlenk flask, t-BuOK (0.741g, 6.60mmol), dehydrated DMF (60ml), and 3,6-di-t-butyl-carbazole (1.841g, 6.60mmol) were added and stirred at room temperature for 30 minutes. Then, 2,4-dibromo-1,3,5-trifluorobenzene (0.580g, 2.00mmol) was added and refluxed for 24 hours. The resulting liquid was poured into water, and dichloromethane was added to perform extraction. Magnesium sulfate was added to the resulting organic layer to dry it, and it was filtered and concentrated with a rotary evaporator. The concentrated product was recrystallized with chloroform and methanol to obtain 1.23g (yield 57.7%) of white crystals of 3BCz-2Br. 1 H-NMR (400MHz, CDCl 3 ,δ): 8.16-8.08 (m, 8H), 7.77 (s, 1H), 7.57-7.48 (m, 8H), 7.16-7.04 (m, 8H), 1.46 (s, 18H), 1.42 (s, 36H).

[0042] In a 300 ml Schlenk flask, 3BCz-2Br (2.130 g, 2.00 mmol) and dehydrated t-butylbenzene (150 ml) were added. After nitrogen replacement, n-butyllithium (3.2 ml, 1.6 M, 5.00 mmol) was added little by little at 0°C and stirred at room temperature for 4 hours. Then, boron tribromide (0.48 mL, 5.00 mmol) was added little by little at 0°C and stirred at room temperature overnight. Then, N,N-diisopropylethylamine (1.0 mL, 6.0 mmol) was added at 0°C and stirred at 180°C for 24 hours. The obtained liquid was returned to room temperature, poured into water, and extracted with chloroform. The obtained organic layer was filtered, and the filtrate was washed with water. Then, magnesium sulfate was added to dry it, and it was concentrated with a rotary evaporator. The concentrated product was separated and purified by silica gel column chromatography (n-hexane / chloroform=9 / 1) to obtain 0.672 g (yield 38.6%) of yellow crystals of BC2B. 1 H-NMR (400MHz, CDCl 3,δ): 8.71 (s, 2H), 8.60 (s, 2H), 8.33 (s, 1H), 8.19-8.11 (m, 6H), 7.89 (d, J = 8.5 Hz, 2H), 7.61 (dd, J = 8.8, 2.0 Hz, 2H), 1.70 (s, 18H),1.67 (s, 18H), 1.65 (s, 18H).

[0043] (Synthesis Example 4) (Synthesis of BCB) [ka]

[0044] In a 300mL Schlenk flask, t-BuOK (1.68g, 18.00mmol), dehydrated DMF (120ml), and 3,6-di-t-butyl-carbazole (4.19g, 18.0mmol) were added and stirred at room temperature for 30 minutes. Then, 1-bromo-2,6-difluorobenzene (1.16g, 6.00mmol) was added and refluxed for 24 hours. The resulting liquid was poured into water, and dichloromethane was added to perform extraction. Magnesium sulfate was added to the resulting organic layer to dry it, and it was filtered and concentrated with a rotary evaporator. The concentrated product was recrystallized with chloroform and methanol to obtain 2.60g (yield 61.0%) of white crystals of 2BCz-Br. 1 H-NMR (400MHz, CDCl 3 ,δ):8.16 (d, J = 1.3 Hz, 4H), 7.68 (dd, J = 9.0, 6.5 Hz, 1H), 7.63-7.61 (m, 2H), 7.51 (dd, J = 8.7, 1.9 Hz, 4H), 7.12 (dd, J = 8.5, 0.5 Hz,4H), 1.47 (s, 36H).

[0045] In a 100 ml Schlenk flask, 2BCz-Br (1.16 g, 1.50 mmol) and dehydrated t-butylbenzene (20 mL) were added. After nitrogen replacement, n-butyllithium (1.5 mL, 1.6 M, 2.5 mmol) was added little by little at 0°C and stirred at room temperature for 4 hours. Then, boron tribromide (0.24 mL, 2.5 mmol) was added little by little at 0°C and stirred at room temperature overnight. Then, N,N-diisopropylethylamine (0.5 mL, 3.00 mmol) was added at 0°C and stirred at 180°C for 24 hours. The obtained liquid was returned to room temperature, poured into water, and extracted by adding chloroform. The obtained organic layer was filtered, and the filtrate was washed with water. Then, magnesium sulfate was added to dry it, and it was concentrated with a rotary evaporator. The concentrated product was separated and purified by silica gel column chromatography (n-hexane / chloroform=9 / 1) to obtain 0.23 g (yield 23.9%) of yellow crystals of BCB. 1 H-NMR (400MHz, CDCl 3 ,δ):δ 9.14 (d, J = 2.0 Hz, 2H), 8.47 (d, J = 1.8 Hz, 2H),8.41 (d, J = 9.0 Hz, 2H), 8.35 (d, J = 8.5 Hz, 2H), 8.27 (d, J = 2.0 Hz, 2H), 8.03 (t, J = 8.3 Hz, 1H), 7.66 (dd, J = 8.8, 2.3 Hz, 2H), 1.67 (s, 18H), 1.53 (s,18H). (Synthesis Example 5) (Synthesis of m-BCz-BCB) [ka] 3,6-Di-t-butylcarbazole (9.22g, 33.0mmol) was added to a 300mL three-neck flask substituted with nitrogen, suspended in 80mL of dehydrated 1,3-dimethyl-2-imidazolidinone, and t-butoxypotassium (3.93g, 35.0mmol) was added under ice-water cooling and stirred at room temperature for 0.5 hours. This mixture was cooled with ice-water and 1-bromo-2,3,6-trifluorobenzene (2.11g, 10.0mmol) was dissolved in 10mL of dehydrated 1,3-dimethyl-2-imidazolidinone and added under a nitrogen stream, and stirred at 140℃ for 21 hours. The reaction solution was cooled with ice-water, water and toluene were added, and the organic layer was separated. The aqueous layer was further extracted twice with toluene, and the combined organic layer was washed three times with water and then washed with saturated saline. The organic layer was dehydrated with magnesium sulfate, filtered, and concentrated to obtain a crude product. The crude product was purified by silica gel column chromatography (eluent: n-hexane / benzene) to obtain 7.29 g (yield 73.7%) of an intermediate as a colorless amorphous substance. 1 H-NMR (400MHz, CDCl 3 ,δ):8.21(d,J=2.0Hz,2H),7.92(d,J=8.8Hz,1H),7.81(d,J=8.8Hz,1H),7.59(dt,J=8.8Hz,1.6Hz,6H),7.35(s,2H),6.97(dd,J=8.4 Hz,2.0Hz,2H),6.94(dd,J=8.4Hz,2.0Hz,2H),6.86(d,J=8.0Hz,2H),6.78(d,J=8.8Hz,2H),1.51(s,18H),1.35(s,18H),1.34(s,18H)

[0046] [ka] The intermediate (5.43g, 5.5mmol) and 110ml of dehydrated xylene were added to a 300mL four-neck flask, and after degassing and nitrogen replacement, t-butyllithium (1.61M n-pentane solution 10.23mL, 16.5mmol) was added dropwise at -10℃ and stirred at 60℃ for 2 hours. Then, boron tribromide (1M dichloromethane solution 16.5mL, 16.5mmol) was added at -40℃ and stirred at room temperature for 0.5 hours. Next, N,N-diisopropylethylamine (4.6mL, 26.4mmol) was added at -10℃ and stirred at 120℃ for 18 hours. The reaction solution was cooled with ice water, and an aqueous sodium acetate solution and toluene were added, and the insoluble matter was filtered through Celite, and the organic layer was separated. Furthermore, the aqueous layer was extracted twice with toluene, and the mixed organic layer was washed with saturated saline. The organic layer was dehydrated with magnesium sulfate, filtered, and concentrated to obtain a crude product. The crude product was purified by silica gel column chromatography (eluent: n-hexane / benzene) to obtain 1.38 g of crude product. 2.71 g of the crude product obtained in the same manner was recrystallized with dichloromethane / methanol to obtain 2.67 g (yield 31.8%) of orange crystals of m-BCz-BCB. 1 H-NMR (400MHz, CDCl 3 ,δ):9.17(d,J=2.0Hz,1H),9.11(d,J=1.2Hz,1H),8.52(d,J=1.6Hz,1H),8.50(d,J=9.2Hz,1H ),8.44(d,J=8.8Hz,1H),8.31(dd,J=6.0Hz,2.0Hz,2H),8.20(d,J=8.4Hz,1H),7.95(d,J=1.6H z,2H),7.71-7.67(m,2H),7.22(d,J=8.8Hz,2H),7.01-6.96(m,2H),6.65(d,J=8.8Hz,1H),6. 24(dd,J=8.8Hz,2.0Hz,1H),1.70(s,9H),1.69(s,9H),1.54(s,9H),1.40(s,18H),1.15(s,9H)

[0047] The synthesized compounds can be purified by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., recrystallization or crystallization using a solvent, etc. The compounds can be identified by NMR analysis, etc. From the above explanation, it will be easily understood by those skilled in the art that the compounds of the present invention that are not listed as examples can be synthesized in the same manner as the above method.

[0048] The boron-containing compound of the present invention can be used as a light-emitting material. The light-emitting material of the present invention can provide a light-emitting device such as an organic photoluminescence device or an organic electroluminescence device. The boron-containing compound of the present invention has a function of assisting the emission of other light-emitting materials (host materials), and can be used by doping other light-emitting materials.

[0049] The organic photoluminescence element of the present invention comprises a substrate and a light-emitting layer containing the light-emitting material of the present invention. The light-emitting layer can be obtained by a coating method such as spin coating, a printing method such as ink-jet printing, a vapor deposition method, or the like.

[0050] The organic electroluminescence element of the present invention has an organic layer between an anode and a cathode. In the present invention, the term "organic layer" means a layer located between the anode and the cathode and substantially made of an organic material, and these layers may contain inorganic materials within a range that does not impair the performance of the light-emitting element of the present invention. The structure of the organic electroluminescent element of the present invention in one embodiment includes an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light emitting layer, a hole blocking layer, an electron transport layer, and a cathode, which are arranged in this order on a substrate, and an electron injection layer is further arranged between the electron transport layer and the cathode. In these multilayer structures, some organic layers can be omitted, and for example, an anode, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode can be arranged in this order on a substrate, or an anode, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode can be arranged. The light emitting material of the present invention may be doped not only in the light emitting layer, but also in the hole injection layer, the hole transport layer, the electron blocking layer, the hole blocking layer, the electron transport layer, or the electron injection layer.

[0051] The substrate is a support for the light-emitting element, and a silicon plate, a quartz plate, a glass plate, a metal plate, a metal foil, a resin film, a resin sheet, etc. are used. In particular, a glass plate or a plate made of a transparent synthetic resin such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferable. When using a synthetic resin substrate, attention must be paid to the gas barrier property. If the gas barrier property of the substrate is too low, the light-emitting element may be deteriorated by the outside air passing through the substrate. For this reason, it is preferable to provide a dense silicon oxide film or the like on one or both sides of the synthetic resin substrate to ensure the gas barrier property.

[0052] An anode is provided on the substrate. A material with a large work function is generally used for the anode. Examples of materials for the anode include metals such as aluminum, gold, silver, nickel, palladium, and platinum; indium oxide, tin oxide, ITO, zinc oxide, In 2 O 3Examples of the conductive material include metal oxides such as ZnO and IGZO, metal halides such as copper iodide, carbon black, and conductive polymers such as poly(3-methylthiophene), polypyrrole, and polyaniline. The formation of the anode is usually performed by sputtering, vacuum deposition, or the like. In addition, in the case of metal fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, conductive polymer fine powder, etc., the anode can be formed by dispersing them in an appropriate binder resin solution and applying it on a substrate. Furthermore, in the case of conductive polymers, a thin film can be formed directly on a substrate by electrolytic polymerization, or a conductive polymer can be applied on a substrate to form an anode.

[0053] The anode can be formed by laminating two or more different materials. The thickness of the anode varies depending on the required transparency. When transparency is required, it is desirable to set the visible light transmittance to usually 60% or more, preferably 80% or more, and in this case, the thickness is usually 10 to 1000 nm, preferably 10 to 200 nm. When opaqueness is sufficient, the anode may have a thickness approximately equal to that of the substrate. The sheet resistance of the anode is preferably several hundred Ω / □ or more.

[0054] As the hole injection layer provided as required, in addition to porphyrin compounds such as copper phthalocyanine, naphthalenediamine derivatives, starburst-type triphenylamine derivatives, triphenylamine trimers and tetramers such as arylamine compounds having a structure in which three or more triphenylamine structures are linked in the molecule by single bonds or divalent groups not containing heteroatoms, acceptor heterocyclic compounds such as hexacyanoazatriphenylene, and coating-type polymer materials can be used. These materials can be formed into thin films by known methods such as vapor deposition, spin coating, and inkjet printing.

[0055] The hole transport material used in the hole transport layer, which is provided as necessary, is preferably one that has a high efficiency of hole injection from the anode and can efficiently transport the injected holes. For this purpose, it is preferable that the material has a small ionization potential, is highly transparent to visible light, has a large hole mobility, is stable, and is unlikely to generate impurities that become traps during production or use. In addition to the above general requirements, when considering application to in-vehicle displays, it is preferable that the element has a high heat resistance. Therefore, a material having a Tg value of 70°C or more is desirable. Examples of the hole transport layer that may be provided as necessary include triazole derivatives, oxadiazole derivatives, imidazole derivatives, carbazole derivatives, indolocarbazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline-based copolymers, and conductive polymer oligomers. More specifically, examples of the compound include compounds containing m-carbazolylphenyl groups, N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine (hereinafter abbreviated as TPD), N,N'-diphenyl-N,N'-di(α-naphthyl)-benzidine (hereinafter abbreviated as NPD), benzidine derivatives such as N,N,N',N'-tetrabiphenylylbenzidine, 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (hereinafter abbreviated as TAPC), various triphenylamine trimers and tetramers, and carbazole derivatives. These can be used alone or in combination of two or more. The hole transport layer may be a film having a single layer structure or a film having a laminate structure. In addition, a coating type polymer material such as poly(3,4-ethylenedioxythiophene) (hereinafter abbreviated as PEDOT) / poly(styrenesulfonate) (hereinafter abbreviated as PSS) can be used as the hole injection / transport layer. These materials can be formed into thin films by known methods such as deposition, spin coating, and inkjet printing.

[0056] In addition, in the hole injection layer or hole transport layer, materials that are usually used in the layer can be further doped with trisbromophenylaminehexachloroantimony P, or polymer compounds having a PD structure in their partial structure, etc. Carbazole derivatives such as CBP, TCTA, and mCP can be used as hole injection / transport host materials.

[0057] Preferred compounds (hi1) to (hi7) that can be used as the hole injection material are listed below.

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] [ka]

[0062] [ka]

[0063] [ka]

[0064] [ka]

[0065] Preferred compounds (ht1) to (ht38) that can be used as the hole transport material are listed below.

[0066] [ka]

[0067] [ka]

[0068] [ka]

[0069] [ka]

[0070] [ka]

[0071] [ka]

[0072] [ka]

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076]

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[0077]

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[0080]

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[0083]

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[0085]

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[0086]

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[0088]

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[0090]

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[0098]

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[0099]

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[0100]

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[0101]

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[0102]

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[0103]

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[0104] As the electron blocking layer provided as necessary, compounds having an electron blocking effect can be used, such as carbazole derivatives such as 4,4',4"-tri(N-carbazolyl)triphenylamine (hereinafter abbreviated as TCTA), 9,9-bis[4-(carbazol-9-yl)phenyl]fluorene, 1,3-bis(carbazol-9-yl)benzene (hereinafter abbreviated as mCP), and 2,2-bis(4-carbazol-9-ylphenyl)adamantane (hereinafter abbreviated as Ad-Cz), and compounds having a triphenylsilyl group and a triarylamine structure, such as 9-[4-(carbazol-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene. These can be used alone or in combination of two or more. The electron blocking layer may be a film of a single layer structure or a film of a laminate structure. These materials can be formed into thin films by known methods such as vapor deposition, spin coating, and inkjet printing.

[0105] Preferred compounds (es1) to (es5) that can be used as the electron blocking material are listed below.

[0106] [ka]

[0107] [ka]

[0108] [ka]

[0109] [ka]

[0110] [ka]

[0111] The light-emitting layer is a layer having a function of emitting light by generating excitons by recombination of holes and electrons injected from the anode and cathode, respectively. The light-emitting layer may be formed by using the light-emitting material of the present invention alone, or may be formed by doping the light-emitting material of the present invention into a host material. Examples of the host material include metal complexes of quinolinol derivatives such as tris(8-hydroxyquinoline)aluminum (hereinafter abbreviated as Alq3), anthracene derivatives, bisstyrylbenzene derivatives, pyrene derivatives, oxazole derivatives, polyparaphenylenevinylene derivatives, compounds having a bipyridyl group and an ortho-terphenyl structure, mCP, thiazole derivatives, benzimidazole derivatives, and polydialkylfluorene derivatives. The light-emitting layer may contain a known dopant. Examples of the dopant include quinacridone, coumarin, rubrene, anthracene, perylene and their derivatives, benzopyran derivatives, rhodamine derivatives, and aminostyryl derivatives. In addition, phosphorescent emitters such as green phosphorescent emitters such as Ir(ppy)3, blue phosphorescent emitters such as FIrpic and FIr6, and red phosphorescent emitters such as Btp2Ir(acac) may be used. These may be used alone or in combination of two or more. The light-emitting layer may be a film having a single layer structure or a film having a laminated structure. These materials can be formed into thin films by known methods such as vapor deposition, spin coating, and inkjet printing. When a host material is used, the amount of the light-emitting material of the present invention that can be contained in the light-emitting layer has a lower limit of preferably 0.1 mass %, more preferably 1 mass %, and an upper limit of preferably 50 mass %, more preferably 20 mass %, and even more preferably 10 mass %.

[0112] Preferred compounds (el1) to (el40) that can be used as the host material of the light-emitting layer are listed below.

[0113] [ka]

[0114]

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[0115]

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[0119]

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[0121]

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[0123]

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[0153] Examples of the hole blocking layer that may be provided as necessary include compounds having a hole blocking effect, such as compounds having a bipyridyl group and an ortho-terphenyl structure, phenanthroline derivatives such as bathocuproine (hereinafter abbreviated as BCP), metal complexes of quinolinol derivatives such as aluminum (III) bis(2-methyl-8-quinolinato)-4-phenylphenolate (hereinafter abbreviated as BAlq), various rare earth complexes, oxazole derivatives, triazole derivatives, and triazine derivatives. These materials may also serve as materials for the electron transport layer. These materials may be used alone or in combination of two or more. The hole blocking layer may be a film having a single layer structure or a film having a laminate structure. These materials may be used to form thin films by known methods such as deposition, spin coating, and inkjet.

[0154] Preferred compounds (hs1) to (hs11) that can be used as the hole blocking material are listed below.

[0155] [ka]

[0156] [ka]

[0157] [ka]

[0158] [ka]

[0159] [ka]

[0160] [ka]

[0161] [ka]

[0162] [ka]

[0163] [ka]

[0164] [ka]

[0165] [ka]

[0166] As the electron transport layer provided as required, in addition to metal complexes of quinolinol derivatives such as Alq3 and BAlq, various metal complexes, triazole derivatives, triazine derivatives, oxadiazole derivatives, thiadiazole derivatives, carbodiimide derivatives, quinoxaline derivatives, phenanthroline derivatives, silole derivatives, etc. can be used. These can be used alone or in combination of two or more. The electron transport layer may be a film of a single layer structure or a film of a laminate structure. These materials can be formed into a thin film by known methods such as a vapor deposition method, a spin coating method, and an inkjet method.

[0167] The electron injection layer, which is provided as needed, can be made of an alkali metal salt such as lithium fluoride or cesium fluoride, an alkaline earth metal salt such as magnesium fluoride, or a metal oxide such as aluminum oxide, but can be omitted in the preferred selection of the electron transport layer and the cathode.

[0168] In the electron injection layer or electron transport layer, a material that is further doped with N-type metal such as cesium in addition to the materials normally used for the layer can be used.

[0169] Preferred compounds (et1) to (et30) that can be used as the electron transporting material are listed below.

[0170] [ka]

[0171] [ka]

[0172] [ka]

[0173] [ka]

[0174] [ka]

[0175] [ka]

[0176] [ka]

[0177] [ka]

[0178] [ka]

[0179]

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[0181]

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[0198]

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[0199]

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[0200] Preferred compounds (ei1) to (ei4) that can be used as the electron injection material are listed below.

[0201] [ka]

[0202] [ka]

[0203] [ka]

[0204] [ka]

[0205] Preferred compounds (st1) to (st5) that can be used as the stabilizing material are listed below.

[0206] [ka]

[0207] [ka]

[0208] [ka]

[0209] [ka]

[0210] [ka]

[0211] A material with a small work function is generally used for the cathode. Examples of the cathode material include sodium, sodium-potassium alloy, lithium, tin, magnesium, magnesium / copper mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide mixture, indium, calcium, aluminum, silver, lithium / aluminum mixture, magnesium-silver alloy, magnesium-indium alloy, and aluminum-magnesium alloy. A transparent or semi-transparent cathode can be obtained by using a transparent conductive material. The thickness of the cathode is usually 10 to 5000 nm, preferably 50 to 200 nm. The sheet resistance of the cathode is preferably several hundred Ω / □ or more.

[0212] In order to protect the cathode made of a low work function metal, it is preferable to further laminate a metal layer having a high work function and stable against the atmosphere, such as aluminum, silver, nickel, chromium, gold, or platinum, on the cathode, since this increases the stability of the element. In addition, in order to improve the contact between the cathode and an adjacent organic layer (e.g., an electron transport layer or an electron injection layer), a cathode interface layer may be provided between the two. Examples of materials used for the cathode interface layer include aromatic diamine compounds, quinacridone compounds, naphthacene derivatives, organic silicon compounds, organic phosphorus compounds, compounds having an N-phenylcarbazole skeleton, and N-vinylcarbazole polymers.

[0213] The light-emitting device of the present invention can be applied to any of a single element, an element having a structure in which elements are arranged in an array, and an element having a structure in which anodes and cathodes are arranged in an XY matrix. EXAMPLES

[0214] The effects of the embodiments of the present invention will be described below. Using the light-emitting material of the present invention, an organic photoluminescence element and an organic electroluminescence element were produced, and the light-emitting properties were evaluated. The light emission characteristics were evaluated using a source meter (Keithley: 2400 series), a spectroradiometer (Konica Minolta: CS-2000), a spectrofluorometer (JASCO: FP-8600), and a 100 mmΦ integrating sphere (JASCO: ILF-835).

[0215] Example 1 In a glove box with a nitrogen atmosphere, toluene solutions of BC2B (sometimes referred to as "A" in the tables and figures), BCB (sometimes referred to as "B" in the tables and figures), 3BCz-BCB (sometimes referred to as "C" in the tables and figures), and 2BCz-BCB (sometimes referred to as "D" in the tables and figures) were prepared. The PL spectra and photoluminescence quantum yields (PLQY) of these solutions were measured. The results are shown in Figures 1 to 6 and Table 1.

[0216] [ka]

[0217] [ka]

[0218] [ka]

[0219] [ka]

[0220] [Table 1]

[0221] Example 2 On a glass substrate with a 50-nm-thick indium tin oxide (ITO) anode, a 10-nm-thick HAT-CN film, a 50-nm-thick TAPC film, and a 10-nm-thick mCBP film were deposited in this order by vacuum deposition (5.0 × 10 -4 The laminate was then laminated at a pressure of 1000 MPa or less (see FIG. 7). The EML film (light-emitting layer) used was the light-emitting material shown in Table 2 and a 10-nm-thick mCBP film containing 2% by weight of TADF. The light-emitting material concentration was set to 10.0% by weight.

[0222] Next, a 10 nm thick PPF film, a 40 nm thick B3PyPB film, and a Liq / Al film were laminated in this order by vacuum deposition to obtain an organic electroluminescence device. The characteristics of the organic electroluminescence device were measured. The light-emitting characteristics are shown in FIGS.

[0223] [Table 2]

[0224] Example 3 In a glove box with a nitrogen atmosphere, a toluene solution of m-BCz-BCB (sometimes referred to as "E" in the tables and figures) was prepared. The PL spectrum and photoluminescence quantum yield (PLQY) of each of these solutions were measured. The results are shown in Figures 11 to 14 and Table 3.

[0225] [ka]

[0226] [Table 3] Example 4 An organic electroluminescence element was obtained in the same manner as in Example 2, except that the luminescent material shown in Table 4 was used for the EML film (light-emitting layer). The characteristics of the organic electroluminescence element were measured, and the luminescence characteristics are shown in FIGS.

[0227] [Table 4]

[0228] As described above, the luminescent materials composed of 2BCz-BCB, 3BCz-BCB, or m-BCz-BCB, which are the compounds represented by formula (I), exhibited superior luminescent properties compared to the luminescent materials composed of BC2B or BCB.

Claims

1. A compound represented by formula (I). 【Chemistry 1】 In formula (I), X, Y and Z each independently represent a hydrogen atom or a 3,6-di-t-butyl-9-carbazolyl group, provided that at least one of Y and Z represents a 3,6-di-t-butyl-9-carbazolyl group.

2. A light-emitting material comprising the compound of claim 1.

3. A light-emitting device comprising the light-emitting material according to claim 2.

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