JP7025885B2 - Nitrogen-containing condensed polycyclic complex aromatic ring compound - Google Patents

Description

The present invention relates to nitrogen-containing condensed polycyclic heteroaromatic ring compounds. More specifically, a nitrogen-containing condensed polycyclic complex aromatic ring compound that can be suitably used as a material for an electron transport layer, an electron injection layer, and a hole blocking layer of an organic electroluminescent element, and the nitrogen-containing condensed polycyclic complex fragrance. The present invention relates to a material for an organic electroluminescent element containing a ring compound, and an organic electroluminescent element configured by using the material for the organic electroluminescent element.

As the nitrogen-containing condensed polycyclic heteroaromatic ring compound, for example, pyridonaphthylidine compound is a compound in which three pyridines are fused, and is generally used for an electron transport layer in an organic electric field light emitting element, such as pyridine and quinoline. Since it has a condensed ring structure longer than that of the above, it is expected to exhibit excellent properties due to this chemical structure. Since the organic electroluminescent device has various excellent characteristics as a display, the development of a material capable of further improving the performance has been actively promoted.

Several examples of nitrogen-containing condensed polycyclic heteroaromatic ring compounds that can be used for the electron transport layer of organic electric field light emitting elements have been known so far, but most of them have nitrogen at a specific position on the pyridonaphthylidine skeleton. It was limited to those with atoms (see, for example, Patent Documents 1 and 2).

Further, the applicability of a pyridonaphthylidine compound to which a specific substituent is bonded to a dye or an organic semiconductor (molecular semiconductors) has been investigated (see, for example, Non-Patent Document 1).

Korean Publication No. 2015-0002266 Gazette Korean Published Patent No. 2014-010787A

Sarah Fernandez et al., 7 others, "Organic LETTERS", 2016, No. 18, p. 3158-3161

As described above, the pyridonaphthalidine compounds described in Patent Documents 1 and 2 are limited to those having a nitrogen atom at a specific position in the pyridonaphthylene skeleton, and only a part of the pyridonaphthylene compound isomers. Was merely disclosed. In the nitrogen-containing condensed polycyclic heteroaromatic ring compound, there are a total of 16 types of isomers even if they have a pyridonaphthylidine skeleton in which one nitrogen atom is present in each ring constituent atom, and these isomers are present. A wide variety of substituents can be appropriately attached to each of the bodies, and a huge number of materials can be designed by selecting these. In the inventions described in Patent Documents 1 and 2, these compounds have not been sufficiently studied. Further, the pyridonaphthalidine compound described in Non-Patent Document 1 has one pyridonaphthylidine skeleton, and a specific substituent having less than 10 carbon atoms is bonded to a specific carbon atom of the skeleton. It was limited to things. Therefore, there is room for further development of nitrogen-containing condensed polycyclic heteroaromatic ring compounds. It is preferable to develop further nitrogen-containing condensed polycyclic heteroaromatic ring compounds and increase their variations in consideration of future development in various applications. Further, when the nitrogen-containing condensed polycyclic heteroaromatic ring compound is used for various purposes in various applications, the range of choices can be expanded, which has great technical significance.

The present invention has been made in view of the above situation, and an object of the present invention is to provide a novel nitrogen-containing condensed polycyclic heteroaromatic ring compound.

The present inventors are expected to have excellent peculiar properties due to the structure in which three nitrogen-containing heteroaromatic rings such as pyridine are fused, and the nitrogen-containing condensed polycyclic heteroaromatic ring compounds such as pyridonaphthylidine compounds are expected. We focused on a group of specific isomers and the like, which were not examined in the inventions described in Patent Documents 1 and 2. Then, it is composed of only one specific nitrogen-containing condensed polycyclic heteroaromatic ring in this specific isomer group, and has 13 or more carbon atoms at a predetermined position of the nitrogen-containing condensed polycyclic heteroaromatic ring. We have succeeded in producing a product to which a substituent is bonded and a product composed of a plurality of the nitrogen-containing condensed polycyclic heteroaromatic rings. In addition, the present inventors have excellent heat resistance, electron injection and / or electron transportability of such a nitrogen-containing condensed polycyclic heteroaromatic ring compound, and electron transport layer and electron injection of an organic electroluminescent element. It has been found that it is suitable as a material for a layer, a hole blocking layer, and the like. The reason why the nitrogen-containing condensed polycyclic heteroaromatic ring compound is excellent in electron injection property and electron transport property is that the nitrogen-containing condensed polycyclic heteroaromatic ring compound has a structure in which three nitrogen-containing heteroaromatic rings are condensed. By having it, the energy level of the lowest empty orbital (LUMO) is lower than that of pyridine, quinoline, phenanthroline, etc. used for the electron transport layer in the organic electric field light emitting element, and the injection (transport) of electrons from the cathode is efficient. It is thought that it can be done in a targeted manner. Furthermore, the present inventors can replace the hydrogen atom of such a nitrogen-containing condensed polycyclic complex aromatic ring compound with another specific atomic group, whereby a nitrogen-containing condensed polycycle having various structures can be substituted. It has been found that the formula heteroaromatic ring compound can be produced. The present invention has been reached with the idea that the above problems can be solved brilliantly.

That is, the present invention has the following formula (1);

(In the formula, X ¹ to X ⁴ are the same or different, and are any of an alkyl group which may have a hydrogen atom, a halogen atom and a substituent, an aromatic hydrocarbon ring group, or an aromatic heterocyclic group. Represents a bonded carbon atom or nitrogen atom, and at least ^one of X1 to ^X4 is ^a nitrogen atom. Y1 to Y3 ^are the same or different, and have a hydrogen atom, a halogen atom, and a substituent. It represents a carbon atom or a nitrogen atom bonded to any of an alkyl group, an aromatic hydrocarbon ring group, or an aromatic heterocyclic group which may have, and at ^{least one} of Y1 to Y3 is nitrogen. It is an atom. N is an integer of 1 to 4. L represents a monovalent substituent having 13 or more carbon atoms, a 2- to 4-valent linking group, or a direct bond, and when n is 1, L is a monovalent substituent having 13 or more carbon atoms, when n is 2, L is a divalent linking group or a direct bond, and when n is 3 or 4, L is an n-valent linking group. It is a nitrogen-containing condensed polycyclic heteroaromatic ring compound represented by).
The present invention is also a material for an organic electric field light emitting device containing the nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention.
The present invention is also an organic electroluminescent device configured using the material for the organic electroluminescent device of the present invention.

The nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention is excellent in heat resistance, electron injection property and / or electron transport property, and is a material for an electron transport layer, an electron injection layer, a hole blocking layer, etc. of an organic electric field light emitting element. It is suitable as.

It is a figure which shows the result of the cyclic voltammetry of the nitrogen-containing condensed polycyclic complex aromatic ring compound of this invention. HOMO (highest occupied molecular orbital) -LUMO (lowest empty orbital) of nitrogen-containing fused polycyclic complex aromatic ring compounds (1) to (12) having a structure in which pyridine, quinoline, phenanthroline, and nitrogen-containing heteroaromatic rings are fused. It is a reference figure which shows the result of the molecular orbital calculation of the orbital). It is a figure which shows the distribution of the molecular orbital (HOMO orbital / LUMO orbital) of the nitrogen-containing condensed polycyclic complex aromatic ring compound of this invention. It is a figure which shows the distribution of the molecular orbital (HOMO orbital / LUMO orbital) of the nitrogen-containing condensed polycyclic complex aromatic ring compound of this invention. It is a figure which shows the synthetic route of the nitrogen-containing condensed polycyclic complex aromatic ring compound which has a halogen atom in a preferable form of this invention. It is a figure which shows the synthetic route of the nitrogen-containing condensed polycyclic complex aromatic ring compound which has a halogen atom when the conventional method is applied. It is a schematic diagram which showed an example of the structure of the organic electroluminescent element of this invention. It is a figure which showed the measurement result of the voltage-current density characteristic of the organic electroluminescent element which used the nitrogen-containing condensed polycyclic complex aromatic ring compound manufactured in the Example. It is a figure which showed the measurement result of the current density-current efficiency characteristic of the organic electroluminescent element which used the nitrogen-containing condensed polycyclic complex aromatic ring compound manufactured in the Example. It is a figure which showed the measurement result of the voltage-current density characteristic of the organic electroluminescent element using the compound of the comparative example. It is a figure which showed the measurement result of the current density-current efficiency characteristic of the organic electroluminescent device using the compound of the comparative example.

The present invention will be described in detail below.
It should be noted that a combination of two or more of the individual preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

In the above general formula (1) in the nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention, the above L is a monovalent substituent having 13 or more carbon atoms, a 2- to 4-valent linking group, or a direct bond. show. Above all, it is preferable that L represents a monovalent substituent having 13 or more carbon atoms or a divalent to tetravalent linking group. Further, when n is 1 (when the nitrogen-containing fused polycyclic heteroaromatic ring compound of the present invention has only one nitrogen-containing condensed polycyclic heteroaromatic ring), L is a monovalent substitution having 13 or more carbon atoms. It is the basis. The monovalent substituent is not particularly limited as long as the total number of carbon atoms is 13 or more, and is, for example, a diarylamino group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, and hydrogen of these groups. One or more of the atoms may be substituted with a substituent such as a halogen atom, an alkyl group, an alkoxy group, an alkenyl group or an alkynyl group.

The number of carbon atoms of the above 2- to tetravalent linking group is not particularly limited, and when the valence of the linking group is n-valent, (n-1) hydrogen atoms are eliminated from the above-mentioned monovalent substituent. It is possible to use the one having the above structure. The lower limit of the number of carbon atoms of the divalent to tetravalent linking group is usually 1, preferably 2, more preferably 3, further preferably 4, and particularly preferably 5. preferable.
Further, the lower limit of the number of carbon atoms of the monovalent substituent and the 2- to tetravalent linking group is more preferably 15; even more preferably 18; even more preferably 20; 22. Most preferably.
Further, the upper limit of the number of carbon atoms of the monovalent substituent and the 2- to tetravalent linking group is not particularly limited, but from the viewpoint of easy synthesis, for example, 50 is preferable, and 30 is more preferable. ..

In the above general formula (1) in the nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention, the monovalent substituent or the 2- to 4-valent linking group in L is an aromatic hydrocarbon ring and / or an aromatic complex. It is preferable to have a ring. Among them, the monovalent substituent or the 2- to 4-valent linking group in L is at least one selected from the group consisting of an aromatic hydrocarbon ring, a benzimidazole ring, a dibenzothiophene ring, a dibenzofuran ring, and a carbazole ring. It is more preferable to have. As a result, according to the molecular orbital calculation, the lowest empty orbital (LUMO) is unevenly distributed near the nitrogen-containing condensed polycyclic heteroaromatic ring, and the highest occupied molecular orbital (HOMO) is an aromatic hydrocarbon ring or the above-mentioned specific aroma. LUMO and HOMO are separated from each other by being unevenly distributed near the group heterocycle. Therefore, when the nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention is used as a material for an organic electric field light emitting element, for example, a hole blocking layer or an electron transporting layer, and comes into contact with holes, for example, holes are formed. Nitrogen-containing condensation because holes come into contact with holes via HOMO, which is unevenly distributed on the side of aromatic hydrocarbon rings that are stable to holes, rather than polycyclic heteroaromatic rings that are unstable with respect to holes. It is considered that the decomposition of the polycyclic heteroaromatic ring compound can be further suppressed and the device life is extended.

Further, in the above general formula (1) of the nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention, the 2- to tetravalent linking group in L may have a structure in which a plurality of aromatic hydrocarbon rings are directly bonded. More preferred. As a result, LUMO and HOMO are further separated. As a result, when the nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention is used as a material for an organic electric field light emitting device, it can be more stabilized not only for reduction but also for oxidation, and the device life is longer. It is considered to be. It is more preferable that the 2- to tetravalent linking group in L has a structure in which two or more aromatic hydrocarbon rings are bonded in a zigzag structure. As a result, the effect of stabilization is considered to be remarkable.

In the above general formula (1) in the nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention, X ¹ to X ⁴ are the same or different, and may have a hydrogen atom, a halogen atom, and a substituent. Represents a carbon atom or a nitrogen atom to which any of a group, an aromatic hydrocarbon ring group, or an aromatic heterocyclic group is bonded. In other words, X ¹ to X ⁴ may represent the same or different carbon atom to which a hydrogen atom is bonded, represent a carbon atom to which a halogen atom is bonded, or have a substituent. An aromatic hydrocarbon ring group to which an alkyl group is bonded represents a carbon atom bonded to an aromatic hydrocarbon ring group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. Represents a bonded carbon atom or a nitrogen atom. The same applies to Y ¹ to Y ³ . At least one of X ¹ to X ⁴ is a nitrogen atom, and at least one of Y ¹ to Y ³ is a nitrogen atom. Hereinafter, halogen atoms, alkyl groups, aromatic hydrocarbon ring groups, and aromatic heterocyclic groups that X ¹ to X ⁴ and Y ¹ to Y ³ may have will be described.

The halogen atom is preferably a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and more preferably a fluorine atom.
As the above-mentioned alkyl group, for example, a linear alkyl group having 1 to 18 carbon atoms, a branched chain alkyl group having 3 to 18 carbon atoms, and a cycloalkyl group having 3 to 18 carbon atoms are preferable.
Specific examples of the linear alkyl group having 1 to 18 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group and an n-heptyl group. Examples thereof include an n-octyl group and an n-decyl group.
Specific examples of the branched alkyl group having 3 to 18 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, an isohexyl group and a 2-ethylhexyl group.
Specific examples of the cycloalkyl group having 3 to 18 carbon atoms include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group and the like.
As the alkyl group, a linear alkyl group having 1 to 18 carbon atoms or a branched alkyl group having 5 to 18 carbon atoms is preferable, and among these, the upper limit of the carbon number is preferably 14 and 10. More preferably, for example, a methyl group, an ethyl group, a tert-butyl group, a 2-ethylhexyl group, and an octyl group are particularly preferable.

As the aromatic hydrocarbon ring group, those having 6 to 18 carbon atoms are preferably mentioned, and specifically, benzene, naphthalene, anthracene and the like are mentioned as more suitable ones.
The upper limit of the number of carbon atoms of the aromatic hydrocarbon ring group is preferably 14, more preferably 10, still more preferably 8, and specifically, benzene is particularly preferable.

The aromatic heterocyclic group contains a heteroatom which is an atom other than carbon and hydrogen as a ring-constituting atom, and those having 0 to 12 carbon atoms are preferable, and specifically, pentazole. Five-membered ring nitrogen-containing ring groups such as triazole, imidazole, benzoimidazole, oxazole, isooxazole, thiazole, isothiazole, pyrazole, pyrrol, indole, carbazole, furan, benzofuran, dibenzofuran, thiophene, benzothiophene, dibenzothiophene and the like. Five-membered ring heterocyclic groups; six-membered ring heterocyclic groups such as pyridine, pyrazine, piperidine, morpholine, thiazine and the like are preferred. Among these, the aromatic heterocyclic group preferably has an upper limit of 8 carbon atoms, more preferably 6 carbon atoms, and even more preferably 5. Further, the lower limit of the number of carbon atoms is preferably 1, more preferably 2, and even more preferably 3. As the aromatic heterocyclic group, those having a nitrogen atom such as pyridine, pyrazine, furan, pyrrole, thiophene and pyrrolidone are particularly suitable.

The alkyl group, aromatic hydrocarbon ring group, or aromatic heterocyclic group which the above X ¹ to X ⁴ and Y ¹ to Y ³ may have may further have a substituent. Examples of the substituent include an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a halogen atom, a cyano group, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and 2 to 2 carbon atoms. Examples thereof include 12 alkylamino groups or arylamino groups having 7 to 18 carbon atoms. Further, the aromatic hydrocarbon ring group or the aromatic heterocyclic group which the above X ¹ to X ⁴ and Y ¹ to Y ³ may have may have an alkyl group as a substituent.

The alkyl group, aromatic hydrocarbon ring, aromatic heterocyclic group, and halogen atom as the substituent are preferably the same as those described above.

The alkoxy group having 1 to 12 carbon atoms includes a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a tert-butoxy group, an n-pentyloxy group and an n-hexyloxy group. , N-Heptyloxy group, n-octyloxy group and the like in a linear or branched chain form are preferable.
The number of carbon atoms of the alkoxy group having 1 to 12 carbon atoms is preferably 1 to 8, more preferably 1 to 6, and even more preferably 1 to 3.

Examples of the aryloxy group having 6 to 12 carbon atoms include a phenyloxy group and a benzyloxy group.
The aryloxy group having 6 to 12 carbon atoms is preferably 6 to 10 carbon atoms among the above-mentioned aryloxy groups. More preferably, it is 6-8. More preferably, it is 6.

As the alkylamino group having 2 to 12 carbon atoms, an acyclic or cyclic dialkylamino group having 2 to 12 carbon atoms such as a dimethylamino group, a diethylamino group, a pyrrosinyl group and a morpholinyl group is preferable.
The number of carbon atoms of the alkylamino group having 2 to 12 carbon atoms is preferably 2 to 8, more preferably 2 to 6, and even more preferably 2 to 5.

Examples of the arylamino group having 7 to 18 carbon atoms include N-alkyl-N-arylamino groups such as N-methyl-N-phenylamino group; carbons such as diphenylamino group, carbazolyl group, phenoxadinyl group and phenothiazinyl group. A diallylamino group having a number of 12 to 18 is preferable.
The arylamino group having 7 to 18 carbon atoms preferably has 8 to 18 carbon atoms, more preferably 12 to 18 carbon atoms, and even more preferably 12 carbon atoms.

In addition, the substituent may be a dioxaborolanyl group, a stenyl group, a silyl group, a hydroxyl group, a sulfo group, a sulfonyl group, a phosphoryl group or the like.

The substituent may be further substituted with a halogen atom, a hetero atom, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, an aromatic ring or the like as long as the effect of the present invention can be exhibited. The position and number of the substituents are not particularly limited.

Among these, the substituent is preferably an aromatic hydrocarbon ring having 6 to 18 carbon atoms, more preferably an aryl group having 6 to 12 carbon atoms, and further preferably a benzene ring. ..
The above-mentioned alkyl group, aromatic hydrocarbon ring group, aromatic heterocyclic group and substituent do not particularly contribute to the deterioration of heat resistance and performance as a material for an organic electric field light emitting element.

Although X ¹ to X ⁴ and Y ¹ to Y ³ in the nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention have been described in detail, as long as at least one of the above X ¹ to X ⁴ is a nitrogen atom, the above X It is the present invention that ¹ to X ⁴ represent the same or different carbon atom bonded to a hydrogen atom, a carbon atom bonded to a linear or branched alkyl group having 1 to 4 carbon atoms, or a nitrogen atom. Is one preferred form of. Above all, it is particularly preferable that the above ^X1 to ^X4 represent the same or different carbon atom or nitrogen atom bonded to the hydrogen atom. Further, as long as at ^{least one} of the above Y1 to Y3 is ^a nitrogen atom, the above Y1 to Y3 ^are the same or different carbon atoms bonded to a hydrogen atom, and are linear or branched having 1 to 4 carbon atoms. It is one preferred embodiment of the present invention to represent a carbon atom or a nitrogen atom bonded to a chain alkyl group. Above all ^, it is particularly preferable that the above Y1 to ^Y3 represent the same or different carbon atom or nitrogen atom bonded to the hydrogen atom.

In the above general formula (1) in the nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention, at least ^one of the above X1 to ^X4 is a nitrogen atom. In other words, ^one to ^four of the above X1 to X4 are nitrogen atoms. Among them, it is preferable that ^one to ^three of X1 to X4 are nitrogen atoms, more preferably ^one or ^two of X1 to X4 are nitrogen atoms, and it is more preferable that ^one or ^two of X1 to X4 are nitrogen atoms. It is even more preferred that one is a nitrogen atom.
Further, among the above X ¹ to X ⁴ , it is particularly preferable that any one of X ¹ , X ² and X ⁴ is a nitrogen atom.

At least one of the above Y ¹ to Y ³ is a nitrogen atom. In other words, ^one to ^three of the above Y1 to Y3 are nitrogen atoms. Above all, it is preferable that one or two of the above Y ¹ to Y ³ is a nitrogen atom, and it is more preferable that one of the above Y ¹ to Y ³ is a nitrogen atom.
Further, among the above Y ¹ to Y ³ , it is particularly preferable that any one of Y ² and Y ³ is a nitrogen atom.

In the nitrogen-containing condensed polycyclic heteroaromatic ring compound represented by the general formula (1), the substituents that X ¹ to X ⁴ may have and Y ¹ to Y ³ are present. The substituents may be bonded to each other to form a ring structure, or may not form a ring structure, but it is preferable that the ring structure is not formed.

In the nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention, for example, a dimer such as bipyridine is synthesized using a nitrogen-containing heteroaromatic ring compound such as pyridine as a raw material, and the substituent of this dimer is ringed. After the conversion, a nitrogen-containing condensed polycyclic heteroaromatic ring compound having a halogen atom is synthesized by subjecting it to a halogenation reaction, and if necessary, a substituent is added, or the compound is dimerized or multimerized. It can be easily synthesized.
As shown in the reaction formula described later, the present invention causes a cross-coupling reaction between a nitrogen-containing heteroaromatic ring compound having a halogen atom and a metal substituent as a raw material and a nitrogen-containing heteroaromatic ring compound having a halogen atom and a cyano group. In the step of obtaining a dimer of a nitrogen-containing heteroaromatic ring compound having a halogen atom and a cyano group at the 2 and 2'positions, respectively, the halogen atom and the cyano group of the dimer are cyclized to form a cyclic amide compound. Also in the method for producing a nitrogen-containing condensed polycyclic heteroaromatic ring compound, which comprises a step of obtaining the cyclic amide compound and a step of reacting the cyclic amide compound with phosphoryl halide to obtain a nitrogen-containing condensed polycyclic heteroaromatic ring compound having a halogen atom. be.
In the above production method, a nitrogen-containing condensed polycyclic complex aromatic ring having a halogen atom is further reacted with a boronic acid ester to form a nitrogen-containing condensed polycyclic complex aromatic ring represented by the above general formula (1). It is preferable to include a step of obtaining a compound. Examples of the boronic acid ester include those in which a boronic acid ester group and a monovalent substituent having 13 or more carbon atoms are directly bonded, those in which two boronic acid ester groups are directly bonded, and 2 to 4 boronic acid esters. Examples thereof include those in which the groups are bonded via a 2- to 4-valent linking group.
Specifically, first, as shown in the reaction formula below, a dimer such as bipyridine is synthesized using a nitrogen-containing heteroaromatic ring compound such as pyridine as a raw material.

The α and β are the same or different and represent halogen atoms such as fluorine, chlorine and bromine. M represents a metal substituent usually used in a cross-coupling reaction such as a boryl group, a trialkylstanyl group and zinc halide. ^The above X1 to ^X4 and the above Y1 to Y3 ^are the same as those described above in the formula ( ¹ ). As the palladium catalyst, for example, Pd (PPh ₃ ) ₄ is preferable.

Then, as shown in the reaction formula below, the cyano group and the halogen atom, which are the substituents of the dimer, are cyclized under basic conditions to synthesize a cyclic amide compound.

The above α, X ¹ to X ⁴ , and Y ¹ to Y ³ are the same as those described above.
The obtained cyclic amide compound is reacted with phosphoryl halides such as phosphorus oxychloride and phosphorus oxybromide in the presence of an amine catalyst, for example, as shown in the reaction formula below, and has a nitrogen-containing condensed polycyclic formula having a halogen atom. Synthesize a complex aromatic ring compound.

The above γ represents a halogen atom such as chlorine or bromine. ^The above X1 to ^X4 and Y1 to ^{Y3 are} the same as those described above.
The obtained nitrogen-containing condensed polycyclic complex aromatic ring compound having a halogen atom is reacted with a boronic acid ester in the presence of a palladium catalyst as shown in the following reaction formula, and the nitrogen-containing condensed polycyclic complex of the present invention is reacted. Aromatic ring compounds can be synthesized. In the following reaction formula, a boronic acid ester having two boronic acid ester groups is used, but a nitrogen-containing condensed polycyclic formula obtained by changing the number of boronic acid ester groups in one boronic acid ester molecule is used. The number of nitrogen-containing fused polycyclic heteroaromatic rings of the heteroaromatic ring compound can be appropriately changed.

The above L is the same as that described above in the formula (1). The above γ, X ¹ to X ⁴ , and Y ¹ to Y ³ are the same as those described above.
However, the method for producing a nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention is not limited to those described above.

The present invention is also a material for an organic electric field light emitting device containing the nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention. The material for an organic electroluminescent element of the present invention is a material for an electron transport layer, an electron injection layer, and a hole blocking layer of an organic electroluminescent element (hereinafter, also referred to as an electron transport material, an electron injection material, and a hole blocking material). Can be suitably used as.
When the material for an organic electroluminescent element of the present invention is used as an electron transport material, an electron injection material, or a hole blocking material, the material for an organic electroluminescent element of the present invention further comprises an electron transport material, an electron injection material, or a hole blocking material. The material may further contain a compound or the like that can be usually used.

Examples of compounds commonly used in electron transporting materials and electron injecting materials are pyridines such as Tris-1,3,5- (3'-(pyridine-3''-yl) phenyl) benzene (TmPyPhB). Derivatives, quinoline derivatives such as (2- (3- (9-carbazolyl) phenyl) quinoline (mCQ)), 2-phenyl-4,6-bis (3,5-dipyridylphenyl) pyrimidine (BPyPPM). Pyrimidine derivatives, pyrazine derivatives, phenanthroline derivatives such as vasophenantroline (BPhen), 2,4-bis (4-biphenyl) -6- (4'-(2-pyridinyl) -4-biphenyl)-[1,3 5] Triazine derivatives such as triazine (MPT), triazole derivatives such as 3-phenyl-4- (1'-naphthyl) -5-phenyl-1,2,4-triazole (TAZ), oxazole derivatives, 2- Oxaziazole derivatives such as (4-biphenylyl) -5- (4-tert-butylphenyl-1,3,4-oxadiazole) (PBD), 2,2', 2''-(1,3) , 5-Bentryyl) -imidazole derivatives such as Tris (1-phenyl-1-H-benzimidazole) (TPBI), aromatic ring tetracarboxylic acid anhydrides such as naphthalene and perylene, bis [2- (2-hydroxyphenyl) ) Benzothiazolato] Various metal complexes typified by zinc (Zn (BTZ) ₂ ), tris (8-hydroxyquinolinato) aluminum (Alq3), etc., 2,5-bis (6'-(2', 2''-) Examples thereof include organic silane derivatives typified by syrol derivatives such as bipyridyl)) -1,1-dimethyl-3,4-diphenylsilol (PyPySPyPy), and one or more of these can be used.

Examples of compounds that can be usually used as a hole blocking material include the above-mentioned compounds that can be used as an electron transporting material and an electron injecting material, as well as 2,2', 2 "-(1,3,5-benzinetri). Il) -tris (1-phenyl-1-H-benzimidazole) and the like can be mentioned, and one or more of these can be used.
The material for an organic electric field light emitting element of the present invention preferably contains 10 to 100% by mass of the nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention in 100% by mass of the material.

(Organic electroluminescent device)
The present invention is also an organic electroluminescent device configured using the material for the organic electroluminescent device of the present invention.
The organic electric field light emitting device of the present invention is configured to include element constituent members such as an electron transport layer, an electron injection layer, and a hole blocking layer obtained by using the material for the organic electric field light emitting device of the present invention. Often, as the other element constituent member, a general element constituent member manufactured by using a material usually used can be adopted. For example, the organic electroluminescent element of the present invention has a light emitting layer, an anode, and a cathode, and an electron injection layer obtained by using the material for an organic electroluminescent element of the present invention is provided between the cathode and the light emitting layer. The element may have an electron transport layer, if necessary, and a hole transport layer and / or a hole injection layer between the anode and the light emitting layer. Further, the organic electroluminescent device of the present invention may have another layer between each of these layers. In addition, each of these layers may be composed of one layer or may be composed of two or more layers. Further, the organic electroluminescent device of the present invention may be a top-emission type that extracts light to the side opposite to the side where the substrate is located, or a bottom-emission type that extracts light to the side where the substrate is located. May be good.

In the organic electroluminescent device of the present invention, the material for the organic electroluminescent device of the present invention is formed into a film by a commonly used method such as vapor deposition or coating, and an electron transport layer, an electron injection layer, or a hole of the organic electroluminescent device is formed. It can be suitably used as an element component such as a blocking layer.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" means "molar mass%".

Various measurements of the compound synthesized in the examples were carried out as follows.
( ^{1 1} H-NMR measurement)
The sample was dissolved in deuterated chloroform or deuterated dimethylsulfoxide containing tetramethylsilane, and measured by a nuclear magnetic resonance apparatus (Gemini 2000, 400 MHz, manufactured by Varian).
(Pyrolysis temperature measurement)
Using a differential thermogravimetric simultaneous measuring device (TG / DTA6200, manufactured by Seiko Instruments Co., Ltd.), a sample of about 5 mg was placed in an aluminum pan and measured as follows.
Measurement temperature range: Room temperature to 500 ° C
Temperature rise rate: 10 ° C / min
The place where a weight loss of 5 wt% was observed in the obtained pyrolysis curve was defined as the pyrolysis temperature.

(Measurement of glass transition temperature)
Using a differential scanning calorimeter (product name: DSC6220, manufactured by Seiko Instruments Co., Ltd.), a sample of about 3 mg was sealed in a sealed aluminum pan for measurement. The measurement temperature range was 30 ° C to the melting point −10 ° C. (decomposition temperature −10 ° C for a sample without a melting point), and the temperature rise (decrease) rate was 30 ° C / min. The temperature rise and fall was repeated three times, and the place where the baseline was shifted in the temperature raising process portion of the second cycle and the third cycle of the obtained DSC curve was defined as the glass transition temperature (Tg).

(Example 1)
Synthesis of bipyridine compound 1

2-Cyano-3-bromopyridine (10.0 g, 54.6 mmol) and 2-fluoro-3-pyridineboronic acid (9.24 g, 65.6 mmol) are placed in a 1000 mL three-necked flask, and toluene (220 ml) and ethanol (2) are added. It was dissolved in 60 ml), and an aqueous sodium carbonate solution (2.0 M, 60 ml, 120 mmol) was added. Pd (PPh ₃ ) ₄ (1.89 g, 1.64 mmol) was added thereto, and the mixture was heated and stirred overnight while refluxing. This was allowed to cool to room temperature, water was added, the mixture was extracted with ethyl acetate, the organic layer was washed with saturated brine, dried over magnesium sulfate, filtered, and the filtrate was concentrated. The obtained residue was purified by column chromatography to obtain 3.2 g (15.8 mmol) of bipyridine compound 1 (yield 29%).
The physical property values were as follows.
^{1 1} H-NMR (400 MHz, CDCl ₃ ) δ8.78 (d, J = 3.2 Hz, 1H), 8.39 (dd, J = 2.0, 1H) 7.97-8.02 (m, 1H) ), 7.93 (d, J = 8.0Hz, 1H), 7.64 (dd, J = 3.2Hz, 1H), 7.39-7.42 (m, 1H).

Synthesis of cyclic amide compound 2

Bipyridine compound 1 (3.2 g, 15.8 mmol) potassium hydroxide (4.4 g, 79.1 mmol) and t-butyl alcohol (63 ml) were placed in an eggplant flask, and the mixture was heated and stirred overnight while refluxing. This was concentrated, water was added to dissolve it, and then neutralized with 2N hydrochloric acid. The precipitated solid was collected by filtration, washed with water and methanol, and dried under reduced pressure to obtain 1.83 g (9.3 mmol) of cyclic amide compound 2 (yield 59%).
The physical property values were as follows.
^{1 1} H-NMR (400MHz, DMSO-d6) δ12.28 (s, 1H), 8.99 (d, 1H), 8.93 (d, 1H), 8.85 (d, 1H), 8.54 (Dd, 1H), 7.88 (dd, 1H), 7.36 (dd, 1H).

Synthesis of nitrogen-containing condensed polycyclic heteroaromatic ring compound 3 having a bromine atom

Cyclic amide compound 2 (1.83 g, 9.3 mmol) and acetonitrile (70 ml) were placed in a 200 ml two-necked flask, and diisopropylethylamine (0.84 ml, 4.8 mmol) and phosphorus oxybromide (4.0 g, 13. 9 mmol) was added. The reaction solution was heated and stirred overnight while refluxing, and then allowed to cool to room temperature for concentration. Chloroform was added thereto, and the organic layer was washed with an aqueous sodium hydrogen carbonate solution and dried over magnesium sulfate. This was filtered to concentrate the filtrate, and the obtained residue was purified by column chromatography to obtain 546 mg (2.10 mmol) of a nitrogen-containing condensed polycyclic heteroarocyclic compound 3 having a bromine atom (yield). 23%).
The physical property values were as follows.
^{1 1} H-NMR (400 MHz, CDCl ₃ ) δ9.23 (dd, 1H), 9.14 (dd, 1H), 8.91 (dd, 1H), 8.88 (dd, 1H), 7.90 ( dd, 1H), 7.73 (dd, 1H).

Synthesis of nitrogen-containing condensed polycyclic heteroaromatic ring compound 4

Nitrogen-containing condensed polycyclic complex aromatic ring compound 3 (546 mg, 2.10 mmol), boronic acid ester (410 mg, 0.95 mmol), Pd (PPh ₃ ) ₄ (121 mg, 0.11 mmol) having a bromine atom in a Schlenck flask. , Dioxane (11 ml) and an aqueous sodium carbonate solution (2.0 M, 4.6 ml) were added, and the mixture was heated and stirred at 100 ° C. overnight. This was concentrated, chloroform was added, and the mixture was washed with saturated brine. After drying over magnesium sulfate, the filtrate was concentrated by filtration, and the obtained residue was purified by column chromatography to obtain 410 mg (0.75 mmol) of the nitrogen-containing condensed polycyclic heteroaromatic ring compound 4. (Yield 80%).
The physical property values were as follows.
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ9.22 (dd, J = 1.2, 1.6 Hz, 2H), 9.18 (dd, J = 1.6 Hz, 2H), 8.99 (dd) , J = 1.6Hz, 2H), 8.91 (dd, J = 1.6, 2.0Hz, 2H), 8.31 (s, 2H), 8.23 (dd, J = 1.6, 2.0Hz, 2H), 7.86 (dd, J = 4.0Hz, 2H), 7.68 (dd, J = 4.4Hz, 2H) 7.61 (d, J = 8.0Hz, 2H) , 2.30 (s, 6H).

(Example 2)
Synthesis of bipyridine compound 5

4-Cyano-3-bromopyridine (3.9 g, 21.3 mmol), 3-fluoro-4-tributylstanylpyridine (9.05 g, 23.4 mmol), CuI (406 mg, 2.1 mmol) in a 300 mL three-necked flask. Was added and dissolved in dioxane (106 ml). Pd (PPh ₃ ) ₄ (739 g, 0.64 mmol) was added thereto, and the mixture was heated and stirred overnight while refluxing. After allowing to cool to room temperature and concentrating, the obtained residue was purified by column chromatography to obtain 3.9 g (19.6 mmol) of the bipyridine compound 5 (yield 92%).
The physical property values were as follows.
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ8.90 (d, 1H), 8.87 (s, 1H), 8.71 (s, 1H), 8.64 (d, 1H), 7.72 (D, 1H), 7.43 (t, 1H).

Synthesis of cyclic amide compound 6

Bipyridine compound 5 (3.9 g, 19.6 mmol), potassium hydroxide (5.49 g, 97.9 mmol) and t-butyl alcohol (80 ml) were placed in an eggplant flask, and the mixture was heated and stirred overnight while refluxing. It was concentrated, added with water to dissolve it, and then neutralized with 2N hydrochloric acid. The precipitated solid was collected by filtration, washed with water and methanol, and dried under reduced pressure to obtain 4.36 g of cyclic amide compound 6 (including impurities).
The physical property values were as follows.
^{1 1} H-NMR (400 MHz, DMSO-d ₆ ): δ12.2 (s, 1H), 9.96 (s, 1H), 8.94 (d, 1H), 8.70 (s, 1H), 8 .51-8.61 (m, 2H), 8.16 (d, 1H).

Synthesis of nitrogen-containing condensed polycyclic heteroaromatic ring compound 7 having a bromine atom

Put cyclic amide compound 6 (4.36 g) and acetonitrile (170 ml) in a 300 ml two-necked flask, and add diisopropylethylamine (2.0 ml, 11.5 mmol) and phosphorus oxybromide (9.51 g, 33.2 mmol). rice field. The reaction solution was heated and stirred overnight while refluxing, allowed to cool to room temperature, water was added, and the mixture was extracted with chloroform. The organic layer was washed with an aqueous sodium hydrogen carbonate solution and dried over magnesium sulfate. The filtrate was filtered and concentrated, and the obtained residue was purified by column chromatography to obtain 340 mg (1.31 mmol) of a nitrogen-containing condensed polycyclic heteroarocyclic compound 7 having a bromine atom (to bipyridine compound 5). On the other hand, the yield is 6.6%).
The physical property values were as follows.
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ10.02 (s, 1H), 9.50 (s, 1H), 9.10 (d, 1H), 8.92 (d, 1H), 8.44 (D, 1H), 8.25 (d, 1H).

Synthesis of nitrogen-containing condensed polycyclic heteroaromatic ring compound 8

Nitrogen-containing condensed polycyclic complex aromatic ring compound 7 (340 mg, 1.31 mmol) having a bromine atom in a two-mouthed flask, boronic acid ester (622 mg, 1.57 mmol), Pd (PPh ₃ ) ₄ (76 mg, 0. 065 mmol), dioxane (6.5 mL) and sodium carbonate aqueous solution (2.0 M, 1.6 mL) were added, and the mixture was stirred at 100 ° C. overnight. After allowing to cool to room temperature, the mixture was concentrated, chloroform was added, and the mixture was washed separately with saturated brine. The organic layer was dried over magnesium sulfate, filtered and concentrated, and the residue was purified by column chromatography to obtain 30 mg (0.067 mmol) of the nitrogen-containing condensed polycyclic heteroaromatic ring compound 8 (yield 5). .1%).
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ9.57 (s, 1H) 9.23 (dd, 1H), 8.87-8.90 (m, 2H), 8.27 (dd, 1H), 8.02 (m, 1H), 7.90 (d, 1H) 7.78-7.79 (m, 2H), 7.65 (dd, 1H), 7.54-7.59 (m, 2H) ), 7.28-7.42 (m, 3H).

(Example 3)
Synthesis of bipyridine compound 9

2-Cyano-3-bromopyridine (5.0 g, 27.3 mmol), 3-fluoro-2-tributylstanylpyridine (12.6 g, 32.8 mmol), CuI (520 mg, 2.7 mmol) in a 300 mL three-necked flask. Was added and dissolved in dioxane (140 ml). Pd (PPh ₃ ) ₄ (947 mg, 0.82 mmol) was added thereto, and the mixture was heated and stirred overnight while refluxing. Allowed to cool to room temperature and concentrated. The obtained residue was purified by column chromatography to obtain 4.1 g (20.3 mmol) of the bipyridine compound 9. (Yield 74%)
The physical property values were as follows.
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ8.80 (d, J = 6.0 Hz, 1H), 8.64 (d, 1H), 8.10 (dd, 1H), 7.50-7. 65 (m, 2H), 7.47-7.50 (m, 1H).

Synthesis of cyclic amide compound 10

Bipyridine compound 9 (4.1 g, 20.3 mmol), potassium hydroxide (5.7 g, 101.7 mmol) and t-butyl alcohol (100 ml) were placed in an eggplant flask, and the mixture was heated and stirred overnight while refluxing. It was concentrated, added with water to dissolve it, and then neutralized with 2N hydrochloric acid. The precipitated solid was collected by filtration, washed with water and methanol, and dried under reduced pressure to obtain 3.75 g (19 mmol) of the cyclic amide compound 10 (yield 93%).
The physical property values were as follows.
^{1 1} H-NMR (400 MHz, DMSO-d ₆ ): δ12.00 (s, 1H), 9.09 (dd, 1H), 9.00 (dd, 1H), 8.56 (dd, 1H), 7 .91 (dd, 1H), 7.75 (dd, 1H), 5.56-7.59 (m, 1H).

Synthesis of nitrogen-containing condensed polycyclic heteroaromatic ring compound 11 having a bromine atom

Cyclic amide compound 10 (3.75 g, 19.0 mmol) and acetonitrile (140 ml) were placed in a 300 ml two-necked flask, and diisopropylethylamine (1.7 ml, 9.9 mmol) and phosphorus oxybromide (8.18 g, 28. 5 mmol) was added. The reaction solution was heated and stirred overnight while refluxing, allowed to cool to room temperature, water was added, and the mixture was extracted with chloroform. The organic layer was washed with an aqueous sodium hydrogen carbonate solution and dried over magnesium sulfate. The filtrate was filtered and concentrated, and the obtained residue was purified by column chromatography to obtain 546 mg (2.10 mmol) of a nitrogen-containing condensed polycyclic heteroarocyclic compound 11 having a bromine atom (yield 23%). ).
The physical property values were as follows.
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ9.51 (dd, 1H), 9.27 (dd, 1H), 9.07 (dd, 1H), 8.48 (dd, 1H), 7.93 (Dd, 1H), 7.76 (dd, 1H).

Synthesis of nitrogen-containing condensed polycyclic heteroaromatic ring compound 12

Nitrogen-containing condensed polycyclic complex aromatic ring compound 11 (1.04 g, 4.0 mmol) having a bromine atom in a two-mouthed flask, boronic acid ester (1.90 g, 4.80 mmol), Pd (PPh ₃ ) ₄ ( 231 mg (0.20 mmol), dioxane (20 mL), and sodium carbonate aqueous solution (2.0 M, 6.0 mL) were added, and the mixture was stirred at 100 ° C. overnight. After allowing to cool to room temperature, the mixture was concentrated, chloroform was added, and the mixture was washed separately with saturated brine. The organic layer was dried over magnesium sulfate, filtered and concentrated, and the residue was purified by column chromatography to obtain 1.64 g (3.64 mmol) of the nitrogen-containing condensed polycyclic complex aromatic ring compound 12. Rate 91%).
The physical property values were as follows.
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ9.53 (d, 1H), 9.09 (dd, 1H), 9.02 (dd, 1H), 8.55-8.57 (m, 1H) , 8.49 (dd, 1H), 8.21 (d, 1H), 7.88 (d, 1H), 7.83 (dd, 1H), 7.74 (dd, 1H), 7.66 ( d, 1H), 7.41-7.52 (m, 6H), 7.30-7.43 (m, 1H), 7.24-7.26 (m, 2H).

(Example 4)
Synthesis of nitrogen-containing condensed polycyclic heteroaromatic ring compound 13

Nitrogen-containing condensed polycyclic complex aromatic ring compound 11 (2.32 g, 8.91 mmol) having a bromine atom in a flask, boronic acid ester (1.70 g, 4.05 mmol), Pd (PPh ₃ ) ₄ (231 mg, 0). .20 mmol), dioxane (88 mL) and sodium carbonate aqueous solution (2.0 M, 10.2 mL) were added, and the mixture was stirred at 90 ° C. overnight. After allowing to cool to room temperature, the mixture was concentrated, chloroform, THF and water were added, and the precipitated solid was collected by filtration. The obtained solid was washed with THF and water, and then charged into chloroform. This solution was hot-filtered, the filtrate was concentrated, acetone was added and filtered to obtain 0.72 g (1.37 mmol) of the nitrogen-containing condensed polycyclic heteroarocyclic compound 13 (yield 34%).
The physical property values were as follows.
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ9.59 (d, 2H), 9.20-9.21 (m, 2H), 9.04-9.05 (m, 2H), 8.90 ( s, 2H), 8.61 (d, 2H), 8.36 (d, 2H), 7.75-7.89 (m, 6H).

(Comparative Example 1)
Synthesis of nitrogen-containing condensed polycyclic heteroaromatic ring compound 14

Nitrogen-containing condensed polycyclic complex aromatic ring compound 11 (390 mg, 1.50 mmol) having a bromine atom in a two-mouthed flask, benzothiophene boronic acid (401 mg, 2.25 mmol), Pd (PPh ₃ ) ₄ (87 mg, 0). .075 mmol), dioxane (7.5 mL) and aqueous sodium carbonate solution (2.0 M, 1.8 mL) were added, and the mixture was stirred at 100 ° C. overnight. After allowing to cool to room temperature, the mixture was concentrated, chloroform was added, and the mixture was washed separately with saturated brine. The organic layer was dried over magnesium sulfate, filtered and concentrated, and the residue was purified by column chromatography to obtain 370 mg (1.18 mmol) of the nitrogen-containing condensed polycyclic heteroaromatic ring compound 14 (yield 79). %).
The physical property values were as follows.
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ9.54 (dd, 1H), 9.30 (s, 1H), 9.27 (dd, 1H), 8.99 (d, 1H), 8.53 (D, 1H), 7.92-8.98 (m, 2H), 7.89 (dd, 1H) 7.39-7.42 (m, 2H).

(Comparative Example 2)
Synthesis of nitrogen-containing condensed polycyclic heteroaromatic ring compound 15

Nitrogen-containing condensed polycyclic complex aromatic ring compound 11 (520 mg, 2.00 mmol), boronic acid (547 mg, 2.4 mmol), Pd (PPh ₃ ) ₄ (116 mg, 0.10 mmol) having a bromine atom in a two-mouthed flask. ), Dioxane (10 mL) and sodium carbonate aqueous solution (2.0 M, 3.0 mL) were added, and the mixture was heated and stirred at 100 ° C. After allowing to cool to room temperature, the reaction solution was diluted with ethyl acetate, and the organic layer was washed with saturated brine. After drying over magnesium sulfate, the mixture was filtered and concentrated, and the residue was purified by column chromatography to obtain 300 mg (0.83 mmol) of the nitrogen-containing condensed polycyclic heteroarocyclic compound 15 (yield 41%).
The physical property values were as follows.
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ9.62 (d, 1H), 9.19 (dd, 1H), 9.09 (dd, 1H), 8.70 (dd, 1H), 8.64 (D, 1H), 8.35 (d, 1H), 8.23-8.26 (m, 1H), 7.80-7.90 (m, 3H), 7.72 (t, 1H), 7.45-7.52 (m, 2H).

(Heat-resistant)
The nitrogen-containing condensed polycyclic complex aromatic ring compounds synthesized in Examples 1 to 4 and Comparative Examples 1 and 2 are arranged in the order of the carbon number of L in the above-mentioned general formula (1), and their heat resistance (pyrolysis temperature). ) Etc. are shown in Table 1 below. In Table 1 below, Tm represents the melting point, Tg represents the glass transition temperature, Tc represents the crystallization temperature, and Td represents the thermal decomposition temperature (5% weight loss temperature).

From the results in Table 1 above, it was found that the heat resistance improves as the number of carbon atoms in L increases.
Further, the compound 15 having 12 or less carbon atoms in L had a low glass transition temperature Tg, and the similar compound 14 had a low crystallization temperature Tc. Although compound 14 does not have a glass transition temperature Tg, it easily crystallizes even if it is amorphous immediately after film formation because the crystallization temperature is low. Compound 15 is in a liquid state at high temperatures and cannot maintain a stable amorphous film.
On the other hand, compound 8 and compound 12 having 19 carbon atoms in L show a sufficiently high glass transition temperature Tg, and can maintain an amorphous film even at a high temperature.
Compound 13 having 23 carbon atoms in L has extremely high heat resistance and no glass transition temperature Tg, and can maintain a stable amorphous film even at high temperatures. Further, the compound 13 crystallizes at 235 ° C., but the crystallization temperature is 80 ° C. or higher as compared with the compound 14 having 8 carbon atoms, and a stable amorphous film can be maintained even at a high temperature.
Compound 4 having 25 carbon atoms in L has extremely high heat resistance and has no glass transition temperature Tg, and can maintain a stable amorphous film even at high temperatures.

(Stability against reduction)
Cyclic voltammetry of the nitrogen-containing condensed polycyclic heteroaromatic ring compound 4 synthesized in Example 1 was performed. The results are shown in FIG.
Even after repeated measurements, there was almost no change in the redox wave, and it is considered to be stable with respect to reduction.

(Calculation of molecular orbital of HOMO-LUMO)
FIG. 2 shows the HOMO (highest occupied molecular orbital) of the nitrogen-containing fused polycyclic complex aromatic ring compounds (1) to (12) having a structure in which three fused rings of pyridine, quinoline, phenanthroline, and nitrogen-containing heteroaromatic ring are formed. It is a reference figure which shows the result of the molecular orbital calculation of LUMO (the lowest empty orbital). The nitrogen-containing fused polycyclic complex aromatic ring compounds (1) to (12) each correspond to the nitrogen-containing condensed polycyclic heteroaromatic ring contained in the nitrogen-containing condensed polycyclic heteroaromatic ring compound of the present invention. From the calculation results of FIG. 2, it is shown that the LUMO energy levels of the nitrogen-containing condensed polycyclic complex aromatic ring compounds (1) to (12) are lower than those of pyridine, quinoline, and phenanthroline. From this result, it is considered that the nitrogen-containing fused polycyclic heteroaromatic ring compound having a structure in which three nitrogen-containing heteroaromatic rings are condensed can efficiently inject (transport) electrons from the cathode.

(Distribution of molecular orbitals (HOMO orbitals / LUMO orbitals))
FIGS. 3-1 and 3-2 are diagrams showing the distribution of molecular orbitals (HOMO orbitals / LUMO orbitals) of the nitrogen-containing condensed polycyclic complex aromatic ring compound of the present invention.
For example, in Reference Example 1 shown in FIG. 3-1 (where L is only one divalent benzene ring), HOMO is distributed even in the nitrogen-containing fused polycyclic heteroaromatic ring, whereas in FIG. Reference Example 4 (L is a divalent dibenzothiophene ring) shown in -1, Reference Example 5 (L is a divalent carbazole ring) shown in FIG. 3-2, Reference Example 6 (L is 1). In each of the valent benzimidazole rings), the distribution of HOMO in the nitrogen-containing condensed polycyclic heteroaromatic ring is small, and LUMO and HOMO are more separated. Further, with respect to the above-mentioned Reference Example 1, Reference Example 2 (in which L is a structure in which two aromatic hydrocarbon rings are directly bonded in a zigzag structure) and Reference Example 3 (L is 3) shown in FIG. 3-1. In the structure in which the aromatic hydrocarbon rings are directly bonded in a zigzag structure), the distribution of HOMO in the nitrogen-containing condensed polycyclic heteroaromatic ring is smaller, and LUMO and HOMO are more separated. Further, Reference Example 2 is a nitrogen-containing condensed polycyclic complex fragrance with respect to Reference Example 7 shown in FIG. 3-2 (where L has a structure in which two aromatic hydrocarbon rings are directly bonded in a straight line). The distribution of HOMOs on the rings is less, and LUMOs and HOMOs are more separated. It is considered that the more the LUMO and HOMO are separated, the more stable the nitrogen-containing condensed polycyclic heteroaromatic ring compound is to oxidation.

(Convenience of manufacturing method)
When the nitrogen-containing condensed polycyclic complex aromatic ring compound which is the precursor of the nitrogen-containing condensed polycyclic complex aromatic ring compound of the present invention is synthesized by the synthesis method described in Korean Publication No. 2015-0002266, it is commercially available. It is considered that the compound will be synthesized through 5 steps using the raw material (Fig. 5). On the other hand, the synthesis method according to the present invention may be carried out in three steps (FIG. 4). Therefore, the nitrogen-containing condensed polycyclic heteroaromatic ring of the present invention can be synthesized very easily.

(Example 5)
Manufacture and Evaluation of Organic Electroluminescent Device (Organic EL Device) The organic EL device 1 shown in FIG. 6 was manufactured and evaluated by the method shown below.
[Step 1]
As the substrate 2, a commercially available transparent glass substrate having an average thickness of 0.7 mm and having a patterned electrode (anode 3) having a thickness of 150 nm made of ITO was prepared. Then, the substrate 2 having the anode 3 was ultrasonically cleaned in acetone and isopropanol, and then UV ozone cleaning was performed for 20 minutes.
[Step 2]
The substrate 2 was fixed to the substrate holder of the vacuum vapor deposition apparatus. In addition, molybdenum trioxide (MoO ₃ ) and N, N'-di (1-naphthyl) -N, N'-diphenyl-1,1'-biphenyl-4,4'-represented by the following formula (1) Diamine (α-NPD), host material KHLHS-01 purchased from Chemipro Chemicals, luminescent dopant KHLDGF-01 also purchased from Chemipro Chemicals, nitrogen-containing fused polycyclic complex aromatic ring compound 12, lithium fluoride. (LiF) and aluminum (Al) were placed in an aluminal pot and set as a vapor deposition source. Then, the pressure inside the vacuum vapor deposition apparatus was reduced to about 1 × 10 ^-5 Pa, and MoO ₃ was vapor-deposited at 0.75 nm to form a hole injection layer 4. Next, α-NPD was deposited at 40 nm to form a hole transport layer 5. Next, KHLHS-01 was used as a host and KHLDGF-01 was used as a dopant for co-depositing at 30 nm to form a light emitting layer 6. At this time, the doping concentration was set so that KHLDGF-01 was 3% by weight based on the entire light emitting layer 6. Next, the electron transport layer 7 was formed by depositing 40 nm of the nitrogen-containing condensed polycyclic heteroaromatic ring compound 12 on the substrate 2 formed up to the light emitting layer 6. Further, a film was formed by depositing LiF to form an electron injection layer 8 having a film thickness of 1 nm.
[Step 3]
Next, aluminum (cathode 9) was vapor-deposited on the substrate 2 formed up to the electron injection layer 8 so as to have a film thickness of 100 nm to obtain an "element 1" according to an embodiment of the present invention.

(Comparative Example 3)
In the above [step 2], instead of using the nitrogen-containing condensed polycyclic complex aromatic ring compound 12 synthesized in Example 3, tris (8-quinolinolat) aluminum (Alq3) represented by the following formula (2) was used. An "element" which is a comparative example of the present invention was obtained in the same manner as in Example 5 except for the above.

(Emission characteristics of organic electroluminescent device)
A voltage was applied to the element and a current was measured by a "2400 type source meter" manufactured by Keithley. The emission brightness was measured by "BM-7" manufactured by Topcon. The results are shown in FIGS. 7 to 10 and Table 2 below. In addition, the uniformity of the light emitting surface was visually confirmed.

It was clarified that the organic electroluminescent element of Example 5 was superior to the organic electroluminescent element of Comparative Example 3 in terms of brightness and luminous efficiency.

The nitrogen-containing condensed polycyclic heteroaromatic ring compounds of these examples are excellent in heat resistance, electron injection property and / or electron transport property, and are an electron transport layer, an electron injection layer, and a hole blocking layer of an organic electroluminescent element. Suitable as a material for. Further, it is possible to realize an element that is stable when used as the material and has excellent brightness and luminous efficiency.

1: Organic EL element 2: Substrate 3: Anode 4: Hole injection layer 5: Hole transport layer 6: Light emitting layer 7: Electron transport layer 8: Electron injection layer 9: Cathode

Claims (5)

The following formula (1);

(In the formula, X ¹ to X ⁴ are the same or different, and are any of an alkyl group which may have a hydrogen atom, a halogen atom and a substituent, an aromatic hydrocarbon ring group, or an aromatic heterocyclic group. Represents a bonded carbon atom or nitrogen atom, and at least ^one of X1 to ^X4 is ^a nitrogen atom. Y1 to Y3 ^are the same or different, and have a hydrogen atom, a halogen atom, and a substituent. It represents a carbon atom or a nitrogen atom bonded to any of an alkyl group, an aromatic hydrocarbon ring group, or an aromatic heterocyclic group which may have, and at ^{least one} of Y1 to Y3 is nitrogen. It is an atom. N is an integer of 1 to 4. L represents a monovalent substituent having 13 or more carbon atoms, a 2- to 4-valent linking group, or a direct bond, and when n is 1, L is a monovalent substituent having 13 or more carbon atoms , has at least one selected from the group consisting of a benzoimidazole ring, a dibenzothiophene ring, a dibenzofuran ring, and a carbazole ring, and when n is 2, L is a divalent linking group or a direct bond, and when n is 3 or 4, L is an n-valent linking group).) Compound. The nitrogen-containing condensed poly according to claim 1, wherein the divalent to tetravalent linking group in L in the general formula (1) has an aromatic hydrocarbon ring and / or an aromatic heterocycle. Cyclic heteroaromatic ring compound. The nitrogen-containing condensation poly according to claim 2, wherein the divalent to tetravalent linking group in L in the general formula (1) has a structure in which a plurality of aromatic hydrocarbon rings are directly bonded. Cyclic heteroaromatic ring compound. A material for an organic electroluminescent element, which comprises the nitrogen-containing condensed polycyclic heteroaromatic ring compound according to any one of claims 1 to 3. An organic electroluminescent device characterized by being configured by using the material for an organic electroluminescent device according to claim 4.

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