JPH0690521B2 - Organic electronic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an organic electronic material. More specifically, the present invention relates to an organic electronic material characterized by using a novel compound which has not hitherto been known.

[Conventional technology]

In recent years, attention has been paid to organic electronic materials used for organic semiconductors, electrophotographic materials, organic conductors, thermistors and the like.

For example, when an organic electronic material is used as the electrophotographic photosensitive member, the organic photosensitive member has a material having charge generating ability (hereinafter referred to as charge generating material) and a material having charge transporting ability (hereinafter referred to as charge transporting material). Are used in combination, and are used by stacking a charge generation layer and a charge transport layer, or by forming a layer in which a charge generation material is dispersed in a charge transport material. Holes or electrons can be considered as the charge to be transported, but a 1: 1 mixture of polyvinylcarbazole (PVK) and trinitrofluorenone (TNF) can be put to practical use as a charge transport material having "electron transporting ability". Most of the "charge transport materials" are those having a hole transport property such as pyrazoline and hydrazone. A conventional photoreceptor using a charge transport material having a hole transporting ability has to be laminated in the order of a substrate, a charge generation layer and a charge transport layer, and therefore the photoreceptor must be charged with a negative polarity. Therefore, the problem that the photoreceptor is chemically deteriorated by the negatively charged ozone cannot be avoided, and the printing durability is remarkably higher than that of the inorganic photoreceptor such as α-Se or a-Si. It has a drawback that it is low, and further, it has a drawback that a photoreceptor capable of being charged in both positive and negative polarities (bipolar photoreceptor) cannot be obtained. From these points, positively chargeable, that is, electron transportable,
Furthermore, the advent of a photoconductor capable of being charged in both polarities is desired.

As such an organic electronic material, tetracyanoanthraquinodimethane and its derivatives have been proposed (for example, JP-A-57-149259 and JP-A-58-55450).

The tetracyanoanthraquinodimethanes are compounds having a basic skeleton represented by the following formula and substituted with various substituents.

The present inventors have also succeeded in isolating a charge-transfer complex composed of the tetracyanoquinodimethanes and an electron-donating compound as a solid pure product at room temperature, and this charge-transfer complex is an organic electronic material rather than a simple substance. It has been found to be useful as, and has already applied for a patent.

The present inventors replaced at least one of the two benzo-condensed rings of the tetracyanoanthraquinodimethanes described above with another hetero-condensed ring, and further modified the two dicyanomethylene groups into various groups. Compounds were also considered to be useful as organic electronic materials in the same manner, and repeated research was conducted.

[Problems to be solved by the invention]

Therefore, an object of the present invention is to provide a novel organic electronic material which has an excellent electron transporting property and can transport electrons and holes.

[Means and Actions for Solving Problems]

The present inventors have found that the novel compound represented by the following general formula (I) is useful as an organic semiconductor, and completed the present invention.

Represents a heterocycle, and when one represents this heterocycle, the other , Y represents S, Se or Te, R ₁ ,
R ₂ and R ₅ are independent of each other and include H, alkyl,
Aryl, represents an aryl-substituted alkyl group, R ₃ , R ₄ ,
R ₆ , R ₇ and R ₈ are independent of one another and are H, alkyl, aryl, aryl-substituted alkyl, alkoxy, halogen, nitro, cyano or carboxylic acid ester groups CO
₂ R ₁ (in the formula, R ₁ has the same meaning as described above).

Examples of the compound represented by the general formula (I) are shown below by structural formulas.

In the formula, Me represents a methyl group and Et represents an ethyl group.

The compounds of general formula (I) according to the invention can generally be synthesized from the corresponding quinone derivatives.

For example, tetracyanoquinodimethane derivative (X = C (CN) ₂ )
In the case of 1, the corresponding quinone derivative is dissolved in a solvent such as chloroform, dioxane, tetrahydrofuran or the like, and titanium tetrachloride is added to the solution and kept at a predetermined temperature. Then, a solution of malononitrile (CH ₂ (CN) ₂ ) in an amount equivalent to or more than the quinone derivative and optionally a solution of a third organic base is added to this suspension, and the mixture is reacted at a predetermined temperature. After confirming the progress, after completion of the reaction, the reaction solution is concentrated if desired, and then the product is injected into a non-solvent,
Crystallize and purify by recrystallization and the like. Similarly, by replacing malononitrile with another active compound, X is replaced by C
Compounds other than (CN) ₂ can be obtained.

For example, by using malonic acid diester (CH ₂ CO ₂ R ₁ R ₂ ), The compound of X = NCN is obtained by using N, N'-bis (trimethylsilyl) -carbodiimide.

The compound represented by the general formula (I) of the present invention can be used alone as an organic electronic material, but in addition, a charge transfer complex with an electron donor or a salt of an anion or an anion radical is also used. be able to.

When a charge transfer complex is formed using an electron donor, examples of the electron donor include aromatic compounds such as benzene, naphthalene, anthracene, pyrene, and perylene, p-phenylenediamine, and similar condensed ring aromatic compounds. , Tetrathiafulvalene (TTF), tetrathiatetracene (T
TT) and sulfur-containing electron donating compounds such as tetramethylthiafulvalene (TMTSF).

These electron donors and other examples are shown below by structural formulas.

Such a charge transfer complex can be produced by the following method.

(1) Dissolving a compound represented by the general formula (I) and an electron-donating compound in a mixed solvent of a soluble solvent (eg methylene chloride, dichloroethane etc.) and a poor solvent (CCl ₄ etc.) for reaction, Then, the mixed solvent is removed to obtain the target complex.

(2) A method in which the compound represented by the general formula (I) and the electron-donating compound are dissolved in both soluble solvents to cause a reaction, then a poor solvent is added and mixed, and then the solvent is removed to obtain the target complex.

When the compound of the general formula (I) is an anion salt or an anion radical salt, examples of the counter cation include the following.

These salts can be prepared by a conventional method.

〔The invention's effect〕

The novel compound of the present invention represented by the general formula (I) can be usefully used as an organic semiconductor. The compound of the general formula (I) can be used alone, or as a charge transfer complex with an electron donor, or as a salt of an anion or an anion radical. For example, when it is used as a charge transporting material for an electrophotographic photoreceptor, it can be used together with a binder resin such as polycarbonate or polyester to form a charge transporting layer, or it can be contained in a charge generating layer together with a charge generating material.

〔Example〕

Example 1 BTDA-TCNQ (benzothiadiazolo-tetracyanoquinodimethane) 1 The quinone derivative 2 as a raw material is R. Neidlein et al. (Chem. Ber., 115,
2898 (1982)), 4 × 10 ^-2 Torr, 250
What was sublimated at ℃ was used (melting point> 390 ° (decomposition)).

Rubbing in a mortar Pink powder raw material 2 6.0 g (26.5 mmo
l) in one 3 neck round bottom flask with dry chloroform (C
aH ₂ in dry distilled ones) are suspended in 390 ml.

Add 12 ml (4 equivalents) of TiCl ₄ and stir vigorously with a mechanical stirrer. Cool to -50 ℃ in a dry ice-methanol bath, and use malonnitrile (boiling point 103-106 ℃ / 14mmH
g) 55.13 g (77.7 mmol, 2.9 equivalents) and dry pyridine (CaH ₂
42 ml (20 equivalents) of dry chloroform (195 ml) was added dropwise while keeping the temperature at -50 ° C. At this time, the color of the solution changes from orange to purple to yellow. Keep the flask temperature below -10 ° C in an ice-salt bath and stir vigorously for 6.5 hours. Next, when 150 ml of cooled ether is added, green-yellow crystals are precipitated (when the temperature at this time is high, decomposition products (green ones) increase, and tar-like. The same applies when the number of equivalents of is large. Therefore, it is necessary to process the reaction promptly).

At this time, unreacted 2 remained as orange-colored cubic crystals at the bottom of the flask, but this was 1 due to decantation.
The crystals can be easily separated from the crystals (the same applies to recrystallization described later). The solid obtained by separating the green-yellow crystals with a Buchner funnel contains the _Ti salt, so after washing with ether (100 ml x 2), a large amount of water (100 ml x
2) Wash with hot water (~ 50 ° C, 200 ml x 2) and dry under reduced pressure. Yield of crude product 7.16 g (84%, melting point 350-365 ° C (decomposition)). The crude product 1 (1) was fractionated recrystallization with acetone 6.72 g, to obtain a 2 0.2 g, 1 a mixture of 2 0.4 g. At this time, 1 is a pale yellow-green crystal, which is sublimated (4 × 10 ^-2 Torr,
At 300 ° C. a yellow powder (pure 1 ) is obtained.
Final yield 72%, melting point 375-380 ° C (decomposition). Recrystallization from acetonitrile gives yellow needle crystals.

Elemental analysis: Calculated as C ₁₂ N ₈ S ₂ (%) C 45.00; N 34.98; S 20.02 Measured value (%) C 45.19; N 35.16; S 20.14.

Mass: m / e (%) 320 (M ⁺ , 100).

384 (4.53), 364 (4.50), 309 (4.45), 303 ^Sh (4.3
6), 246 (4.04), 239 (4.06).

¹ H-NMR: no proton is observed.

Example 2 TDA-TCNNQ (thiadiazolo-tetracyanonaphthoquinodimethane) 3 The raw material quinone derivative 4 is R. Naefe et al. (Chem. Ber., 90 , 1137).
(1957)) and purified by silica gel (G-22) chromatography (eluent CH ₂ Cl ₂ ) were used (melting point 245-248 ° C. (decomposition)). 4 1.10 g (5.09 mmol) 50 in a 200 ml three neck round bottom flask
Suspend in ml of dry chloroform. Add 2.2 ml (4 equivalents) of TiCl ₄ and cool to 0 ° C. in an ice water bath. While maintaining at 0 ° C., a solution of 6.70 g (102 mmol, 20 equivalents) of malonnitrile and 16 ml (70 equivalents) of dry pyridine in 50 ml of dry chloroform is added dropwise. After stirring at room temperature for 20 minutes, pour into 100 ml of water, separate the _Ti salt, and wash thoroughly with methylene chloride (20 ml x 5).
The layers were quickly separated, the aqueous layer was extracted with methylene chloride (50 ml x 2), the organic layers were combined and washed with water (150 ml x 6), and then Na ₂ was added.
Dry with SO ₄ . Concentrate the solvent at low temperature (~ 20 ℃) (~ 20m
l), 10 ml of ether is added and the yellow precipitate that separates is separated. Crude product 1.01 g (64%, melting point 268-271 ° C (decomposition))
To get This is recrystallized from methylene chloride-hexane to obtain yellow needle crystals having a melting point of 277 to 278 ° C (decomposition). Final yield
55%.

Elemental analysis: Calculated as C ₁₆ H ₄ N ₆ S (%) C 61.53; H 1.29; N 26.90; S 10.27 Measured value (%) C 61.16; H 1.07; N 26.22; S 10.06.

Mass m / e (%) 312 (M ⁺ , 100).

357 (4.44), 296 (4.38).

IR ▲ ν ^KBr _max ▼ / cm ^-1 2218 (CN), 1558 (C =
C).

7.8 to 8.1 (2H, m), 8.6 to 8.9 (2H, m).

Example 3 SeDA-TCNNQ (selena diazolo-tetracyanonaphthoquinodimethane) 5 6 500 mg (1.90 mmol) are ground, suspended in 30 ml dry methylene chloride and 0.85 ml (4 equivalents) TiCl _{4 is} added. Malononitrile 1.32 g (~ 10 eq), dry pyridine 6 ml (40
Gradually add 15 ml of dry methylene chloride solution (eq.
Stir for 8 hours at room temperature while checking by thin layer chromatography. After confirming that the spots of the starting quinone derivative have disappeared, pour into a mixed solution of 100 ml of water and 50 ml of CH ₂ Cl ₂ and extract. The aqueous layer was further extracted with CH ₂ Cl ₂ (50 ml × 2), the organic layers were combined and washed with water (100 ml × 3), and then Na ₂
Dry with SO ₄ . After the solvent was distilled off, 30 ml of ether was added, and the crystals were separately dried to obtain 452 mg (66%) of a crude product. Melting point 330-350 (decomposition). This CH ₂ Cl ₂ - Recrystallization from hexane become yellow powder. Melting point 335-370 ° C (decomposition).

Elemental analysis: Calculated value as C ₁₆ H ₄ N ₆ Se (%) C 53.50; H 1.12; N 23.40 Measured value (%) C 53.31; H 1.00; N 23.30 Example 4 TDA-DCNNQI (thiadiazolo-dicyanonaphthoquinodiimine ) 7 Thiadia Zolonaphthoquinone 4 100 mg (0.463) is dissolved in 10 ml dry CH ₂ Cl ₂ and 0.2 ml TiCl ₄ (4 eq) is added.
N, N'-bis (trimethylsilyl) carbodiimide 830mg
(9.6 eq) 5 ml dry CH ₂ Cl ₂ solution is added and refluxed for 8 hours. Pour into 20 ml of water, separate, and separate the aqueous layer with CH ₂ Cl ₂ (20 ml)
Extracted with water, and the organic layers were combined and washed with water (50 ml), then Na ₂ S
Dry with O ₄ . Evaporate the solvent to give 109 mg (89%) of crude product. This CH ₂ Cl ₂ - Recrystallization from hexane becomes dark yellow powder. Melting point 275-280 ° C (decomposition).

Elemental analysis: calculated for C ₁₂ H ₄ N ₆ S (%) C 54.54; H 1.53; N 31.80; S 12.13 Found (%) C 54.71; H 1.37; N 31.29; S 11.50.

Example 5 SeDA-DCNNQI (selena diazolo-dicyanonaphthoquinodiimine) 8 Selenodiazolonaphthoquinone 6 100mg 20ml dry CH ₂
Suspend in Cl ₂ and add 0.2 ml of TiCl ₄ (4 eq). N, N ′
-Bis (trimethylsilyl) carbodiimide 890 mg (12.
Add 5 eq) of 5 ml dry CH ₂ Cl ₂ solution and reflux for 54 hours.
Pour into 20 ml water and extract with 30 ml CH ₂ Cl ₂ . The aqueous layer CH ₂ C
Extract with l ₂ (20 ml), combine the organic layers and wash with water (50 ml x
After 2), it is dried with Na ₂ SO ₄ . 118 mg of a crude product obtained by distilling off the solvent is recrystallized from CH ₂ Cl ₂ (ClCH ₂ CH ₂ Cl may be used) to obtain a purified product having a melting point of 298-318 ° C. (decomposition). 28 mg
(twenty four%).

Example 6 BTDA-TCNQ.TTT (benzothiadiazolo-tetracyanoquinodimethane.tetrathiatetracene) (1:
1) Complex BTDA-TCNQ (prepared in Example 1) 62 mg (0.2 mmol) 130 ml
Dissolved in CH ₂ Cl ₂ and, using a Soxhlet extractor, dissolve and dissolve 70 mg (0.2 mmol) of tetrathiatetracene (TTT). After all TTT has been extracted, leave at room temperature to obtain 132 mg (~ 100%) of black needles. Melting point> 400 ° C.

IR: ν _CN = 2173 cm ^-1 . Specific resistance ρ (4 for pellets
Measured by the terminal method) = 0.14 to 0.15 Ωcm.

Example 7 BTDA-TCNQ.N, N, N ', N',-TMPD (benzothiadiazolo-tetracyanoquinodimethane.N, N, N ', N'
-Tetramethylparaphenylenediamine) (1: 1) complex BTDA-TCNQ 62 mg (0.2 mmol) was dissolved in 60 ml of boiling dry CH ₂ Cl ₂ and tetramethylparaphenylenediamine 33 mg (0.
2 mmol) in dry CH ₂ Cl _{2 (} 1 ml) is added and left at room temperature for 7 hours. 50 mg (52%) of black powder are obtained. Melting point 225-230 ° C
(Disassembly).

IR: ν _CN = 2171 cm ^-1 . ρ = 8.66Ωcm (measured by the two-terminal method for pellets).

Example 8 [(N-Methylphenazinium) (benzothiadiazolo-tetracyanoquinodimethane anion radical)]
(1: 1) salt Prepared from BTDA-TCNQ and 3 equivalents of LiI in anhydrous CH ₃ CN Dissolve 205 mg (0.63 mmol) in 300 ml boiling dry CH ₂ CN,
N-methylphenazinium methylsulfate 192mg
Add 10ml dry CH ₃ CN solution (0.63 mmol). Allow to stand at room temperature and separate the dark brown needles. Yield 174 mg (61
%). Melting point 219-220 ° C (decomposition).

IR: ν _CN = 2172 cm ^-1 . ρ = 1.66Ωcm (measured by the two-terminal method for pellets).

Elemental analysis: Calculated as C ₂₅ H ₁₁ N ₁₀ S ₂ (%) C 58.24; H 2.15; N 27.17; S 12.94 Measured value (%) C 58.20; H 1.96; N 26.96; S 12.33.

Example 9 Conductivity of Charge-Transfer Complex of BTDA-TCNQ and Electron Donor The specific resistance value was obtained by the two-terminal method or four-terminal method using the charge-transfer complex of BTDA-TCNQ and various electron donors as a pellet. Shown in I.

Example 10 3 parts polyester resin and 2 bisazo pigments on an aluminum substrate
To form a charge generation layer. Then, a solution containing 3 parts by weight of the compound prepared in Example 1 and 2 parts by weight of a polycarbonate resin was applied on the charge generation layer to form a charge transport layer. The film thicknesses of the charge generation layer and the charge transport layer were 2 μ and 20 μ, respectively.

Using the photoconductor formed in this way, it was uniformly charged to the positive polarity and imagewise exposed. The electrostatic contrast was 550V.
Latent image was formed. When each electrostatic latent image was developed to form a copy image, a good image was obtained.

When the latent image forming slap was repeatedly performed, the increase in residual potential was about 100V.

Claims (1)

[Claims] 1. The following general formula (I): Represents a heterocycle, and when one represents this heterocycle, the other , Y represents S, Se or Te, R ₁ ,
R ₂ and R ₅ are independent of each other and include H, alkyl,
Aryl, represents an aryl-substituted alkyl group, R ₃ , R ₄ ,
R ₆ , R ₇ and R ₈ are independent of one another and are H, alkyl, aryl, aryl-substituted alkyl, alkoxy, halogen, nitro, cyano or carboxylic acid ester groups CO
₂ R ₁ (in the formula, R ₁ has the same meaning as described above). ] The organic electronic material characterized by using the compound shown by these.