JP6899578B2 - Electron transport material and electronic material using the electron transport material - Google Patents

Description

Since the present invention has good sensitivity, exhibits electron transport capability at high speed, and has excellent solubility in an organic solvent, an electron transport layer in an ultrathin film can be formed, and thus, for example, fax or copy can be formed. Electronic transport materials that can be applied to various electronic materials such as organic semiconductors, organic ELs, and other ultrathin layers that require an electron transport layer with high flexibility or elasticity in some cases, in addition to a solvent drum, and the same. Regarding electronic materials using electronic transport materials.

Naphthalenetetracarboxylic dianimides (hereinafter, may be referred to as "NTC") represented by the following general formula (XX) as described in Patent Document 1 are promising as electronic materials such as electron transport materials. Has been done.

In the general formula (XX), R and R'are the same or different and represent an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkoxy group.

The biggest drawback of the NTC (XX) is that it has very poor solubility in an organic solvent. For example, when it is used as an electron transport material, it has low compatibility with a binder resin forming a photosensitive layer, and the photosensitivity is low. It sometimes crystallized in the layer.
In order to solve such a problem, by introducing an asymmetric substituent into R and R'in the above formula (XX), each substituent is 90 with respect to the main skeleton (naphthalenetetracarboxylic dianimide). Attempts have been made to prevent stacking of molecules and increase solubility by rotating them in degrees (see, for example, Patent Document 2).
However, introducing an asymmetric substituent is industrially inferior in practicality because the synthesis process is complicated and the yield tends to be low.

In addition, as described in Patent Document 3 and the like, although various substituents NTC (V') have been developed so far, the market is always simpler and yields higher than those conventional products. There is a demand for the development of an electron transporting material capable of high synthesis and having better solubility and electron transporting ability than these conventional products.
In particular, when used as an organic semiconductor material, the presence of impurities hinders electron transfer and causes deterioration, so it is necessary to make the purity as high as 100%.

Furthermore, the present inventors have proposed an electron transporting material containing a pyrazolone derivative (antipyrine derivative) and an electronic material using the electron transporting material (Japanese Patent Laid-Open No. 2014-210768 << hereinafter, prior application >>).

Special Fair 1-39098 Gazette Japanese Patent No. 3292461 Japanese Patent No. 4339617

The present invention has a request for further expansion of applications (for example, an electron transport material capable of forming a layer with an ultrathin film) than the above-mentioned previously applied electron transport material, and an electron transport material satisfying this request and the material. An object of the present invention is to provide an electronic material using the above.

In order to solve the above problems, it is possible to apply to a wide range of materials (particularly, excellent solvent solubility, and the formation of an ultrathin layer associated therewith, as well as higher sensitivity and higher moving speed than the previously applied material. Ease of use) and the provision of materials at a low price are important, and it is necessary to consider from a different point of view from the previous application.
Therefore, the present inventors are more soluble than conventional products, have high flexibility or elasticity, are easy to form in an ultrathin layer, and are easy to attract electrons, and therefore have a wider range of applications at a price. As a result of repeated studies to develop an inexpensive electron transport material, the following findings were obtained.
(1) Analyzing the chemical structure of the previously proposed electron transport material, first finding out which group is directly involved in electron transport,
(2) Next, when a means for obtaining the compound having the above group at a low cost, in other words, a means for synthesizing the compound (raw material) by a simple manufacturing process was pursued, it was obtained by a conventionally known synthetic route. If the compound is a group that is directly involved in electron transport and exhibits highly sensitive electron transport ability, and this group is bonded to the main part of the previously proposed electron transport material, it has extremely excellent solubility. It was found that it also has.

The present invention has been made based on the above findings.
The gist is an electron transport material containing a pyrazole derivative represented by the formula (I).

In formula (I),
A and B represent the same or different alkyl group, cycloalkyl group, aryl group or aralkyl group.
In the present invention, the alkyl group may have an alkoxy group and / or a halogen atom, and the cycloalkyl group, the aryl group and the aralkyl group may have an alkyl group and / or a halogen atom. The aralkyl group may have an alkyl group and / or a halogen atom on the alkylene chain.
Z represents any one of the eight structural formulas (Z-1) to (Z-8) of the following formula (II).

The gist of the present invention is also an electronic material using such an electron transporting material.

According to the electron transport material containing the novel pyrazole derivative of the present invention, the following effects can be obtained.
(1) It exhibits extremely high sensitivity and excellent electron transport capability.
(2) Since it exhibits high solubility in organic solvents and is also excellent in compatibility with various binder resins, it is easy to form in an ultrathin layer, and good electrons are formed even in an ultrathin layer. It exhibits mobility and can be used in a wide range of applications.
(3) In addition, due to the high solubility and high compatibility of (2), when used for a photosensitive layer, even if the layer is extremely thin, uniform dispersion can be ensured throughout the layer, and the performance of the layer can be improved. Not only can it be made uniform, but the stability of the layer over time can be ensured.
(4) Further, even when the electron transport layer is used for various electronic materials having an acute-angled shape, it is extremely easy because it has high flexibility as well as the above-mentioned characteristics (1) to (3). It can be applied and has a fairly wide range of uses.

The electron transport material (Electron Transport Material; hereinafter, also referred to as “ETM”) of the present invention having the above-mentioned excellent performance is a known charge generation material (hereinafter, also referred to as “CGM”), positive. By combining with a hole transport material (hereinafter, also referred to as “HTM”), a single-layer photoconductor drum with high sensitivity and high stability can be formed, and a laminated photoconductor drum can be formed. It can also be used.
In addition, it can be suitably used for organic semiconductors, organic ELs, and other electronic materials that require an ultrathin and flexible electron transport layer.

The electron transport material of the present invention uses a compound (compound of the following formula (III)) obtained by a conventionally known synthetic route (the route of the following formula (IV)) as a group involved in electron transport. Since it can be manufactured extremely easily and inexpensively, it is possible to further expand its applications.

It is a figure which shows the NMR analysis result of the compound (ZI-11) obtained in Example 1. FIG. It is a figure which shows the IR analysis result of the compound (ZI-11) obtained in Example 1. FIG. It is a figure which shows the NMR analysis result of the compound (ZI-22) obtained in Example 2. FIG. It is a figure which shows the IR analysis result of the compound (ZI-22) obtained in Example 2. FIG. It is a figure which shows the NMR analysis result of the compound (ZI-33) obtained in Example 3. It is a figure which shows the IR analysis result of the compound (ZI-33) obtained in Example 3. FIG. It is a figure which shows the NMR analysis result of the compound (ZI-42) obtained in Example 4. FIG. It is a figure which shows the IR analysis result of the compound (ZI-42) obtained in Example 4. FIG. It is a figure which shows the NMR analysis result of the compound (ZI-54) obtained in Example 5. It is a figure which shows the IR analysis result of the compound (ZI-54) obtained in Example 5. It is a figure which shows the NMR analysis result of the compound (ZI-63) obtained in Example 6. It is a figure which shows the IR analysis result of the compound (ZI-63) obtained in Example 6. It is a figure which shows the NMR analysis result of the compound (ZI-74) obtained in Example 7. It is a figure which shows the IR analysis result of the compound (ZI-74) obtained in Example 7. It is a figure which shows the NMR analysis result of the compound (ZI-84) obtained in Example 8. It is a figure which shows the IR analysis result of the compound (ZI-84) obtained in Example 8.

In the electron transporting material of the present invention containing the pyrazole derivative represented by the formula (I), A and B represent the same or different alkyl group, cycloalkyl group, aryl group or aralkyl group.
When A and B are alkyl groups, the alkyl group preferably has 1 to 16 carbon atoms, more preferably 1 to 8 carbon atoms, and may be linear or branched chain, and is an alkoxy group. Or may have a halogen atom. Specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, isopentyl, neopentyl, t-pentyl, n-hexyl, isohexyl, n-heptyl. , N-octyl, 2-ethoxyethyl, 4-methoxypropyl, perchloromethyl, perfluoroethyl, trifluoromethyl and the like.

When A and B are cycloalkyl groups, the cycloalkyl group has preferably 12 or less carbon atoms, more preferably 8 or less carbon atoms, and may have an alkyl group or a halogen atom on the ring. Specific examples thereof include cyclopentyl, cyclohexyl, cycloheptyl, 2,6-dimethylcyclohexyl, 2-isopropyl-5-methylcyclohexyl, 1-5-substituted chlorocyclohexylphenyl groups, 1-5-substituted fluorocyclohexyl groups and the like. ..

When A and B are aryl groups, the aryl group preferably has 12 or less carbon atoms, more preferably 10 or less carbon atoms, and may have an alkyl group or a halogen atom on the ring. Specific examples thereof include phenyl, naphthyl, diphenyl, trill, xsilyl, mesityl, cumenyl, 2-ethyl-6-methylphenyl, 1-3-substituted chlorophenyl groups and 1-3-substituted fluorophenyl groups.

When A and B are aralkyl groups, the aralkyl group has preferably 12 or less carbon atoms, more preferably 10 or less carbon atoms, and may have an alkyl group or a halogen atom on the ring. Specific examples thereof include benzyl, phenethyl, 2,6-dimethylbenzyl and the like.

In the above formula, Z is preferably one of the eight formulas (Z-1) to (Z-8) from the viewpoint that the electronic material exhibits excellent electron transporting ability. Further, Z may be a diimide compound represented by the following general formula (Z-9) in addition to the above eight formulas (Z-1) to (Z-8).

In the above general formula, R ₃₂ and R ₃₃ represent H, F, CF ₃ , and CH ₃ .

The raw material acid anhydrides for synthesizing the diimide compound represented by the above general formula are pyromellitic acids and pyromellitic acid derivatives. In the diimide compound of (Z-9) represented by the above general formula, _{when both R 32} and R ₃₃ are H, it becomes (Z-2). That is, the diimide compound of (Z-9) contains (Z-2), and (Z-2) is particularly preferable among the diimide compounds of (Z-9).

As the diimide compound of (Z-9), the following compounds can be specifically exemplified in addition to (Z-2). Each compound of (Z-9) has pyromellitic acid as a basic skeleton, and even if it has a substituent at the 1,1'position of the benzene ring existing in the center, it does not have a substituent. It is a compound which may be used.

In addition to the above eight formulas (Z-1) to (Z-8), Z may be a diimide compound represented by the following general formula (Z-10).

The diimide compound represented by the above general formula is a biphthalic acid and a biphthalic acid derivative. The diimide compound (Z-10) represented by the above general formula is a compound in which two basic skeletons are bonded, but the binding site of the benzene ring, which is the basic skeleton, is not particularly limited. Further, it may be a biphthalic acid having a substituent on the benzene ring which is the basic skeleton.

As the diimide compound of (Z-10), the following compounds can be specifically exemplified in addition to (Z-3).

In addition to the above eight formulas (Z-1) to (Z-8), Z may be a diimide compound represented by the following general formula (Z-11).
In the above general formula, R ₃₄ is a substituent selected from an oxygen (O), sulfur (S), dimethyl group, carbonyl group, sulfonyl group, dimethylsilyl group, trifluoromethyl group and indenyl group, and R ₃₅ is a substituent. , Hydrogen (H) or fluorine (F).

The diimide compounds represented by the above general formula are diphthalic acids and diphthalic acid derivatives. Specific examples of the (Z-11) diimide compound represented by the above general formula include the following compounds in addition to (Z-4), (Z-6), (Z-7), and (Z-8). Can be exemplified. Each compound of (Z-11) has diphthalic acid as a basic skeleton, and two phthalic acid skeletons are bridged by oxygen, sulfur, or the like.

Further, Z may be a diimide compound represented by the following general formula (Z-12) in addition to the above eight formulas (Z-1) to (Z-8).

In the above general formula, R ₄₀ represents O or S.

The diimide compounds represented by the above general formula are diphthalic acids and diphthalic acid derivatives. Specific examples of the (Z-12) diimide compound represented by the above general formula include the following compounds. Each compound of (Z-12) has diphthalic acid as a basic skeleton, and two phthalic acid skeletons are bridged by oxygen or sulfur.

Further, Z may be a diimide compound represented by the following general formula (Z-13) in addition to the above eight formulas (Z-1) to (Z-8).

In the above general formula, R ₃₆ is O or S, and R ₃₇ is H or F.

The diimide compound represented by the above general formula has three benzene rings at the center of the compound, and has a symmetrical structure in the left-right and up-down directions.

Specific examples of the diimide compound (Z-13) include the following compounds. Each compound has three benzene rings as a basic skeleton, and is bonded to two benzene rings on the left and right by bridging with oxygen or sulfur around the benzene ring.

Further, Z may be a diimide compound represented by the following general formula (Z-14) in addition to the above eight formulas (Z-1) to (Z-8).

In the above general formula, R ₃₈ is O or S, and R ₃₉ represents a substituent selected from O, S, a dimethylalkyl group and a sulfonyl group.

The diimide compound represented by the above general formula has a symmetrical structure centered on a skeleton in which two benzene rings are bonded via a _{substituent R 39.}

Specific examples of the diimide compound (Z-14) include the following compounds. Each compound has four benzene rings as a basic skeleton, and is bonded to the left and right benzene rings via oxygen or sulfur around the two benzene rings.

Further, in addition to the above eight formulas (Z-1) to (Z-8), a diimide compound represented by the following structural formula may be used. Specifically, perylenes having perylene at the center of the diimide compound (Z-15), diphthalates consisting of three benzene rings (Z-16), and two or more 5-membered or 6-membered cyclic hydrocarbons It may be a diimide compound (Z-17) which is bonded and becomes a compound center. Further, (Z-17) may be a diimide compound in which carbon-carbon is bridged by oxygen, sulfur, kei or the like.

The pyrazole derivative contained in the electron transport material of the present invention can be obtained as a diimide compound by reacting an acid anhydride with aminopyrazole. As described above, the raw material of the diimide compound as shown in the above eight formulas (Z-1) to (Z-8) and further (Z-9) to (Z-17) can be a raw material of polyimide. Any acid anhydride can be used.

The source of the groups on both sides of formula (I), i.e. the compound of formula (III) below, can be obtained, for example, by the reaction of formula (IV) below, described in Chemical Abstracts Vol56 4746.

A and B in the formulas (III) and (IV) are the same as those in the above formula (I).

The compound of the formula (III), the source of the Z group of the above formula (I), that is, the acid anhydride which is the raw material of any one of the eight compounds of the formula (II), and the eight kinds of the formula (II). The reaction with the acid anhydride which is the raw material of the above diimide compounds other than the above is easily generated by heating and stirring while dehydrating using a Dean Stark trap or the like, and has high purity and high yield, according to the above formula (I). ) Can be obtained.

In the formula (II), the raw material of the compound represented by (Z-1) is naphthalenetetracarboxylic dianhydride, and the raw material of the compound represented by (Z-2) is pyromellitic dianhydride. The raw material of the compound represented by Z-3) is 4,4'-biphthalic dianhydride, and the raw material of the compound represented by (Z-4) is 3,3', 4,4'-diphenylsulfonetetra. It is a carboxylic acid dianhydride, and the raw material of the compound represented by (Z-5) is 4,4'-(4,4'-isopropyridenediphenoxy) diphthalic acid anhydride, and it is (Z-6). The raw material of the compound represented by is 4,4'-oxydiphthalic acid anhydride, and the raw material of the compound represented by (Z-7) is 3,3', 4,4'-benzophenonetetracarboxylic dianhydride. Yes, the raw material of the compound represented by (Z-8) is 4,4'-(hexafluoroisopropyridene) diphthalic dianhydride, which may be monoanhydride or not. You may. Further, the above-mentioned diimide compounds other than the eight kinds represented by (Z-1) to (Z-8) in the formula (II) may be monoanhydride or may not be anhydrous.

Further, in the present invention, a mixture thereof is prepared in advance for the reaction between the carboxylic acid anhydrides of the raw materials (Z-1) to (Z-8) in the formula (II) and the compound of the formula (III). , The mixture may be supplied to the reaction system, or each may be supplied to the reaction system separately. The same applies to the reaction between the acid anhydride which is the raw material of the diimide compound other than the eight types represented by (Z-1) to (Z-8) in the formula (II) and the compound of the formula (III). ..
As the solvent at this time, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, toluene, tetrahydrofuran, anisole and the like are used.
The pyrazole derivative (I), which is a reaction product, can also be purified with an adsorbent such as activated carbon, white clay, and silica gel.

As the electronic material of the present invention, an electron transport material (ETM) containing the above pyrazole derivative is used.
The ETM of the present invention is, for example, combined with a known charge generating material (CGM), hole transport material (HTM), binder resin, or the like to form a photosensitive layer, and this layer is provided on a conductive support to generate electrons. A photographic photoconductor can be formed.

Examples of the CGM that can be combined with the ETM of the present invention include known ones as exemplified below.
Phthalocyanin compounds, disazo compounds, trisazo pigments, monoazo pigments, perylene pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metallic naphthalocyanine pigments, squaline pigments, trisazo pigments, indigo pigments, azurenium pigments, cyanine pigments, There are pyririum salts, anthanthrone pigments, triphenylmethane pigments, threne pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments and the like, and these may be used alone or in combination of two or more.

Among them, metal-free phthalocyanine, aluminum phthalocyanine, vanadium phthalocyanine, cadmium phthalocyanine, antimony phthalocyanine, chrome phthalocyanine, copper 4-phthalocyanine, germanium phthalocyanine, iron phthalocyanine, dichlorotin phthalocyanine, chloroaluminum phthalocyanine, (oxy) titanyl, which have high photosensitivity. Phthalocyanine compounds such as phthalocyanine, chloroindium phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, magnesium phthalocyanine, dialkyl phthalocyanine, tetramethyl phthalocyanine, and tetraphenyl phthalocyanine are preferable.
As the crystal form of the above-mentioned oxytitanyl phthalocyanine, in addition to α, β, γ, Y type, amorphous and mixed type crystals thereof can be used, and for metal-free phthalocyanine, γ type and the like can be used.
Further, a mixture of chloroindium phthalocyanine and oxytitanyl phthalocyanine, a derivative obtained by reacting a polyhydric alcohol with oxytitanyl phthalocyanine, and a compound obtained by reacting butanediol and oxytitanyl phthalocyanine can also be used.

Examples of the HTM that can be combined with the ETM of the present invention include known ones as exemplified below.
There are compounds represented by the following general formulas (V) to (VIII), and these may be used alone or in combination of two or more.

In the above formula, R 1 to R _{3 are one selected from} hydrogen atom, halogen atom, alkyl group, allyl group, alkoxy group, aryl group, dialkylamino group and diphenylamino group, respectively, and l, m, n indicates an integer of 0 or more and 2 or less.
R _{4 to} R ₇ represent one selected from a hydrogen atom, an alkyl group, an allyl group, an alkoxy group, an aryl group, a dialkylamino group, and a diphenylamino group, respectively.
R _{8 to} R ₁₁ represent one selected from a hydrogen atom, an alkyl group, an allyl group, and an aryl group.
R _{12 to} R ₁₄ represent one selected from a hydrogen atom, an alkyl group, an allyl group, and an aryl group.

Among the above HTMs, preferably, the one having a large molecular weight and high mobility is not affected by the molecular structure.

Further, in the photosensitive layer, the ETM of the present invention includes CGM and HTM generally used for the photoconductor, as well as known ETMs represented by the following general formulas (IX) to (XIII). , Can be used together.
These ETMs may be used alone or in combination of two or more.

In the above formula, R _{15 to} R ₂₅ represent one selected from a hydrogen atom, a halogen atom, an alkyl group, an allyl group, an alkoxy group, an aryl group, a dialkylamino group, and a diphenylamino group, respectively.
R _{26 to} R ₃₁ are hydrogen atom, cyano group, nitro group, halogen atom, hydroxy group, alkyl group, aryl group, heterocyclic group, ester group, alkoxy group, aralkyl group, allyl group, amide group, amino group, It is one selected from an acyl group, an alkenyl group, an alkynyl group, a carboxyl group, a carbonyl group and a carboxylic acid group, X is one selected from oxygen, sulfur and = C (CN) ₂ , and Y is one selected. Oxygen or sulfur.

As the binder resin for forming the photosensitive layer containing ETM, CGM, HTM, etc. as described above, known ones as exemplified below are used.
Polycarbonate resin, styrene resin, acrylic resin, styrene-acrylic resin, ethylene-vinyl acetate resin, polypropylene resin, vinyl chloride resin, chlorinated polyether resin, vinyl chloride-vinyl acetate resin, polyester resin, furan resin, nitrile resin, alkyd Resin, polyacetal resin, polymethylpentene resin, polyamide resin, polyurethane resin, epoxy resin, polyarylate resin, dialylate resin, polysulfone resin, polyethersulfone resin, polyallylsulfone resin, silicone resin, ketone resin, polyvinylbutyral resin, poly There are ether resin, phenol resin, EVA (ethylene / vinyl acetate) resin, ACS (acrylonitrile / chlorinated polyethylene / styrene) resin, ABS (acrylonitrile / butadiene / styrene) resin and epoxy allylate, etc., which may be used alone or in two types. The above may be mixed and used.

In addition to the above-mentioned components, various additives such as a plasticizer, a surfactant, a leveling agent, and an antioxidant can be added to the photosensitive layer.

As the conductive support on which the photosensitive layer is formed as described above, various materials having conductivity as illustrated below are used.
Elemental metals such as iron, aluminum, copper, tin, platinum, gold, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, brass; plastic materials with the above metals deposited or laminated. Glass coated with aluminum iodide, tin oxide, indium oxide or the like; a resin or the like in which conductive fine particles such as carbon black are dispersed can be mentioned.
The shape of the conductive support may be either a sheet shape or a drum shape according to the structure of the image forming apparatus to be used, and the support itself has conductivity or the surface of the support is conductive. It suffices to have sex. Further, the conductive support preferably has sufficient mechanical strength in use.

Example 1
A pyrazole derivative in which Z of the formula (I) is (Z-1) was synthesized as follows.

In the reaction vessel, compound (Z-1-1): 1,4,5,8-naphthalenetetracarboxylic dianhydride (1.35 g (5.0 mmol)) and compound (I-1) of Chemical formula 7: 2 .94 g (12 mmol) and 15 ml of toluene (hereinafter, ml is referred to as mL) were added, and the mixture was reacted under reflux for 3 hours. During the reaction, Dean-Stark trap was used to remove by-product water.
After completion of the reaction, the mixture was cooled, 50 mL of methanol was added, and the precipitated crystals were filtered.
The obtained crystals were washed with methanol and then purified with tetrahydrofuran and activated carbon to obtain 0.80 g (yield 22%) of the compound of Chemical formula 8 (ZI-11).

Melting point measurement, elemental analysis, NMR analysis, IR analysis, and HPLC analysis of the obtained crystals were performed. The results are shown below.

<Melting point measurement>
This was performed using a melting point measuring device (trade name "B545" manufactured by BUCHI, Germany). The results were as follows.

Melting point: 328 ° C

<Elemental analysis>
This was done using the trade name "EA1108 type" manufactured by FISONS. The results were as follows.

Measured value (%) C: 66.62%, H: 5.14%, N: 11.71%
Calculated value (%) C: 69.79%, H: 5.30%, N: 11.63%

<NMR analysis>
Measurements were performed with _{CDCl 3} using an R-1200 high-speed sweep correlation nuclear magnetic resonance apparatus (manufactured by Hitachi, Ltd.). The result was as shown in FIG.

<IR analysis>
The measurement was carried out by the KBr method using an infrared spectroscopic analyzer (trade name manufactured by Thermo Co., Ltd .; NICOLET380;). The result is as shown in FIG.

<HPLC analysis>
When the analysis was performed using an HPLC apparatus (trade name manufactured by Shimadzu Corporation; CR-7A;), the purity was 99.9% (area percentage).

Examples 2-8
Compound 7 (I-2) and Compound 23 (Z-2-1) (Example 2),
Compound 7 (I-3) and Compound 23 (Z-3-1) (Example 3),
Compound 7 (I-2) and Compound 23 (Z-4-1) (Example 4),
Compound 7 (I-4) and Compound 23 (Z-5-1) (Example 5),
Compound 7 (I-3) and Compound 23 (Z-6-1) (Example 6),
Compound 7 (I-4) and Compound 23 (Z-7-1) (Example 7),
Compound 7 (I-4) and Compound 23 (Z-8-1) (Example 8)
In the same manner as in Example 1 except that the solvent, reaction time, and purification method are as shown in the same table, the compound of Chemical formula 8 (ZI-22) (Example 2), ( ZI-33) (Example 3), (ZI-42) (Example 4), (ZI-54) (Example 5), (ZI-63) (Example 6), (ZI-74) (Implementation) Examples 7) and (ZI-84) (Example 8) were obtained.
The table shows the yield of the pyrazole derivative before purification and the yield after purification together.

The melting point measurement, elemental analysis, NMR analysis, IR analysis, and HPLC analysis of the crystals obtained in Examples 2 to 8 were carried out in the same manner as in Example 1, and the results of the melting point measurement, elemental analysis, and HPLC analysis are shown in Table 2. The results of NMR analysis and IR analysis are shown in FIGS. 3 to 16.

<Solubility in organic solvent>
The solubility evaluation of the compounds obtained in Examples 1 to 8 was carried out as follows. The results are shown in Table 3.
0.1 g of each compound was placed in 1 mL of tetrahydrofuran and stirred for 1 minute. A completely dissolved compound was indicated by "◯", a slightly dissolved compound was indicated by "Δ", and a slightly dissolved compound was indicated by "x".

<Photoreceptor characteristics as ETM>
The photoconductor characteristics of the compounds obtained in Examples 1 to 8 whose dissolution was confirmed in the above solubility test were evaluated as follows.
0.1 g of α-type oxytitanyl phthalocyanine as CGM was placed in 100 mL of tetrahydrofuran together with 4.7 g of Z-type polycarbonate having a molecular weight of 40,000, and dispersed by an ultrasonic disperser for 24 hours.
There, 1.7 g each of the compounds obtained in Examples 1 to 8 as ETM and m-TPD (N, N'-diphenyl-N, N'-di (m) represented by the above formula (VI) as HTM. -Trill) benzidine) 3.5 g each was added and mixed and dissolved to obtain a coating liquid.

Each of the obtained coating liquids is applied to an aluminum drum-shaped conductive support with a single coating device manufactured by Mitsubishi Materials Techno Co., Ltd. so that the film thickness is 30 μm, and is positively charged. A layered electrophotographic photosensitive member was prepared.
In order to evaluate the sensitivity of the produced electrophotographic photosensitive member, a half exposure amount (μJ / cm ² ) was measured using an electrophotographic evaluation device "CINDIE743" manufactured by Gentec. The results are also shown in Table 3. The half-exposure amount is the amount of exposure required to halve the surface potential of the charged photosensitive layer (photoconductive layer) when the surface is exposed. The smaller the half-exposure amount, the more sensitive the photoconductor. Show that it is large.

^{The half-exposure amount is generally evaluated as having good sensitivity at 0.28 μJ / cm 2} or less and a photoconductor drum at about 0.35 μJ / cm ^{2 in} a positively charged single-layer photoconductor using α-type oxyttanyl phthalocyanine. Is inadequate and is considered defective.

The pyrazole derivative of the present invention is a compound having excellent solubility in organic solvents and compatibility with synthetic resins as well as electron transport ability, and has a uniform electron transport ability in ultrathin films. Not only is it extremely useful as an electron transport material (ETM) for electrophotographic photosensitive members, which can be formed well and is used in image forming devices such as electrostatic copiers, facsimiles, and laser beam printers, but also organic semiconductors. , Organic EL, conductive polymer and the like, can be suitably used in a wide range of fields.
Moreover, since raw material compounds can be synthesized and obtained at extremely low prices, their applications are extremely wide-ranging.

Claims (2)

An electron transporting material containing a pyrazole derivative represented by the formula (I).
In formula (I),
A and B represent the same or different alkyl group, cycloalkyl group, aryl group or aralkyl group.
Z represents any one of the following eight structural formulas (Z-1) to (Z-8).
An electronic material using the electronic transport material according to claim 1.