DE2364763A1 - PROCESS FOR THE MANUFACTURING OF DICYANOMETHYLENTHIOPHENES AND THEIR DERIVATIVES AND THEIR USE IN ELECTROPHOTOGRAPHIC LIGHT SENSITIVE MATERIALS - Google Patents

Description

DR. BERG DIFL ..- 1 Nto. » ι At-s-

PAT EHfA H WA LTB 8 MUNICH βθ. MAUERKIRCHERSTR. 4β

Attorney file 24 485 December 27! 973

Be / Sch

Kabushiki Kaisha Biooh Tokyo /

"Process for the preparation of Bicyanoittethyienthiopiien and their derivatives and their use in electrophotographic light-sensitive Materials"

In summary, the present invention relates to electrophotographic light-sensitive materials having a photoconductive layer formed on an electroconductive support, the photoconductive layer being an organic photoconductive compound (monomer or polymer) and 4-dicyanomethylene-4H-indene / T ', 2- b7-thiophene - / 427 4 0 9 8 2 8/1112 _ ₂ _

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and / or S-dicyanomethylene-SH-indene - /? ', 1-bT-thiophene and / or their derivatives as sensitizers, as well as a process for the preparation of such compounds from 4H-indene / Ji 2-fe7 ^ -thiophene -4-one or 8H-indene / 2, t-bJ7-thiophen-8-one or their derivatives and malonitrile »

Contains an electrophotographic photosensitive material an electroconductive support having a photoconductive layer formed thereon. The principle of an electrophotography Method is that an electrostatic latent image is formed by imagewise exposing a charged photoconductive layer and the image then by a developer or toner (in liquid or Powder form), which is electrically deposited on the latent image to form a visible image photoconductive. Layer inorganic photoconductor, such as photoconductive Zinc oxide or selenium is used. Eeuierding was - the use of an organic photoconductive 7erbini & iisg ,? for example a photoconductive polymer, like Pöly-K-vinylcarbazole, instead of the inorganic photoconductor suggested. The organic photoconductive ITe bonds have, besides other advantages, · those of the transparent and mechanical flexibility. Furthermore, they are easy to form as photoconductive layersi on the other hand only absorb light in the ultraviolet range ^ " of the spectrum, but are not visible to the visible

sensitive. To overcome this disadvantage, do yours To "shift absorption into the visible region of the spectrum, dye sensitizers are added to the organic photoconductive compounds. Such dyes, as they have been used up to now, but are generally not stable and fade quickly so that the organic photoconductive compounds lose their sensitivity in the visible range. Accordingly, electrophotographic photosensitive materials made using organic photoconductive compounds, containing dye sensitizers have found limited practical use.

It is therefore an object of the present invention, a stable sensitizer and an improved electrophotographic.es to provide photosensitive material containing this stable sensitizer «

The present invention relates to electrophotographic photosensitive materials having a photoconductive layer formed on an electroconductive support wherein the photoconductive layer is an organic photoconductive compound such as a photoconductive monomer or polymer and 4-dicyanomethylene-4H-indene / T, 2-b7-thiophene or S-dicyanomethylene-eH-indene / ^. i-bT-thiophene or contains their derivatives as a sensitizer, and a process for the preparation of such compounds and their

409828/1112

Derivatives.

I'm generally an electrophotographic.es it contains photosensitive Material an electroconductive support and a photoconductive layer formed on the support.

The electrophotographic photosensitive materials of the present invention are characterized in that the photoconductive layer contains an organic photoconductive compound which reacts with 4-dicyanomethylene-4H-indene-Z ~ j 2-jo7-thiophene or e-dicyanomethylene-eH-indene / z ", 1-b / ⁷ -thiophene and their derivatives of the following general formulas are sensitized, these compounds being used as sensitizers for the organic photoconductive compound.

NC-G-CT

IC-C-CiT

409828/1 1 1 2

(A)

(B)

-5-

wherein the radicals R ₁ , R ₂ , R ^, R ^ R, - and Rg are hydrogen atoms or nitro groups.

These connections are named as follows:

A. S-dicyanomethylene-SH-indene / ?, 1-b / -thiophene

B. 4-dicyanomethylene-4H-indene ^ T ", 2-b7'-thiophene.

The electrophotographic photosensitive materials of the present invention can be prepared by having a photoconductive one on the electroconductive support Layer, which layer forms a variety of organic photoconductive monomers, such as N-vinylcarbazole, or organic photoconductive polymers such as poly-W-vinylcarbazole and 4-dicyanomethylene-4H-indene / T, 2-b7-thiophene or S-dicyanomethylene-eH-indene / ^ ", 1-b7-thiophene or their derivatives as described above. 4-Dicyanomethylene-4H-indene / T, 2-b7-thiophene or 8-dicyanomethylene-8H-indene ^ 2 *, 1-b7_thiophene or their derivatives in an amount of about 0.01 to 1.2 moles per mole of organic photoconductive monomer or per monomeric unit of the organic photoconductive polymer used (where 1 mol of organic photoconductive polymer is represented by the monomeric unit of the polymer). ·

4-dicyanomethylene-4H-indene / T, 2-b7-thiophene or 8-dicyanomethylene-8H-indene ^ 2,1-b_7-thiophene and their derivatives, the

-6- 409828/1112

find use according to the present invention, show the following structural formulas:

(D

NC-C-CN
Dicyanomethylene- ^ H-indene-ZT.2-b7-thiophene

(H)

NC-C-CN

2-Nitro-4-dicyanomethylene-4-H-indene- / ^: T. 2-b7-thiophene

(III)

NC-C-CN

6-nitro-4-dicyanomethylene- ' ^ί ^ -H-inden- / ϊ. 2-b7-thiophene

(IV)

NC-C-CN

2.6-Dinitro-4-dicyanomethylene-4H-indene- / ^: i. 2-b7-thiophene

4 0 982871112

-7-

(ν)

NC-C-CN
6. S-Dinitro - ^ - aicyanomet-hylen- ^ H-ind'en-ZT. 2-b7-thiophene

(VI)

NC-C-CN

2.6.8-trinitro-4-dicyanomethylene-4li-inaen- / T. 2-b7-thiophene

NC-C-ClT

(VII)

S-dicyanomethylene-SH-indene- ^, 1 -b7-thiophene

NC-C-CN

(VIII)

2-nitro-8-dcyanomethylene-8H-indene- _i / ?, 1-b7 ~ thiophene

409828/1112

-8th-

(IX)

6_Nitro-8-dicyanomethylene-8H-indene- / 2 ', 1- [b /' - thiopienes

NC-G-GN

(X)

2. ö-Dinitro-S-dicyanomethylene-SH-indene- ^, 1 -b7-thiophene

(ΧΙ)

4. e-Dinitro-S-dicyanomethylene-eH-inaen- ^ Z. 1 -b ^ -thiophene

NC-C-GN

(XII)

2.4.6-trinotro-8-di cyanomethylene-8H-indene- / 2.1 -b7-thiophene

4 0 9 8 2 8/1112

Organic photoconductive compounds according to the present invention Invention use are:

The preferred organic photoconductive polymer " seeds include poly-N-vinylcarbazole, chlorinated or brominated Poly-N-vinyl carbazole, polyvinyl pyrene, polyvinyl naphthalene, Polyvinyl anthracene, poly-9-vinyl fluorene, poly-1-arylimidazole, Bromopyrene-formaldehyde resin and poly-p-phenylene-1ο3c4-oxadiazole '

Preferred organic photoconductive monomers hear E-vinylcarbazole, - ET-ethylcarbazole, anthracene and pyrene,

However, it is used as an organic photoconductive compound Poly-U-vinyloarbazole and chlorinated or brominated poly-ΪΓ-vinylcarbazole preferred.

On suitable electroconductive supports, which are used in the present For example, metal foils such as aluminum foils and synthetic foils can be used in the invention Resin films coated with an aluminum layer are.

The electrophotographic photosensitive materials can be made as follows:

About 0.01 to about 1 mole of 4-dicyanomethylene-4H-indene ^ T, 2-b / ⁷ -thiophene or S-dicyanomethylene-SH-indene / ^, 1-b7-thiophene

-10- 409828/1112

or their derivatives are mixed with 1 mole of organic monomer or monomeric unit of the organic photoconductive polymer and dissolves the mixture in an organic Solvents such as tetrahydrofuran or dioxane to form a photosensitive solution. Polyester resin, ScLvolach resin or acrylic resin can be added to this solution, if desired. Furthermore, polychlorobiphenyl can these Solution to be added * The obtained photosensitive solution can be applied to a surface of an electroconductive Carrier, for example using an air knife, after which it is left to set and then dried « .

Examples:

409828/1112 -n

example 1

A photosensitive solution that is photoconductive
Preparation for the production of a photoconductive layer contains, was prepared from the following ingredients:

Poly-N-vinylcarbazole 387 mg (2 mmol)

6. 8-Dinitro-4-dicyanomethylene-4-Hr
inden- ^ T.2-b7-thiophene 65 mg (0.2 mmol)

Polyester adhesive 49000

(Trademark for a polyester resin.

from E.I. Du Pont de Nemours

& Go., Inc.) 38 mg

This photosensitive solution was coated on an aluminum layer on a polyester resin film (thickness 75 / u) using an air knife at a distance of 200 / u, and then the layer was in
a silica gel dryer to evaporate the solvent and dried for about 10 minutes at a temperature of 60 ⁰ C and about 2 minutes at a temperature
dried at 120 ° C. This gave a photoconductive layer with a thickness of about 7 / U on the aluminum layer.

The sensitivity of the electrophotographic thus obtained photosensitive material (No. 1) of the present Invention was made using an "electrostatic paper analyzer" ("Electrostatic paper analyzer Type SP-4-28 of the Kawaguchi Denk! Seisakusho ") as" follows rated:

-12-409828 / 1112

- 12 - '

The material obtained above was divided into two parts ^ The photoconductive layer was charged negatively or positively by means of a corona discharge of about -6kV or + 6IcV for 20 seconds, whereby a surface electric potential Vdo was obtained and then the layer was subjected to 20 seconds Dark attenuation, giving a residue surface potential Vpo. This charged photosensitive material was exposed to a tungsten filament lamp, the luminosity of which was adjusted to 20 lux on the surface of the photosensitive layer. The Z _e it (in seconds), which was required to reduce the surface electric potential auf'die half or 1/5 of the residual surface potential Vpo was measured * the length of exposure, E ^ νο (-'- ^αχ "sec.) and E ^ y ₁ - (lux · sec) required to reduce the surface electric potential to half or 1/5 of Vpo was calculated from the equation "20 lux χ time (in seconds)." The values E ^ y ₂ ^{and E} 1/5 S ^e 6 ^en indicate the sensitivity of the electrophotographic light-sensitive material, the lower the value of E ^ , ^ or 'E ^ / t, the higher the sensitivity of the light-sensitive material. The values for Vpo, E ^ ₂ and Ε ^, γ are given in Table I below.

Similar results are obtained in Table I below with the corresponding 8-dicyanomethylene-8H compound

£ 09828/1 1 12

-1-3-

charge

-Table I. ^E 1/5
(lux sec.) Vpo
(V) ^E 1/2
(lux sec.) 44.9 480 14.0 33.7 425 11.7

Examples 2 "to 8

An electrophotographic light-sensitive materials (No. to No. 8) of the present invention were obtained by repeating the same procedure as in Example 1 except that the indicated organic photoconductive compound, in Table II S _e nsibilisator, PoIyester-adhesive 49000 and Tetrahydrofuran were used and that the photoconductive layer had the thickness shown in Table II.

Table II

PoIy-N- 6.8-Dinitro-_ 65 mg Poly- Tetra Strength of vinyl- 4-dicyano- (0.2 mmol) ester hydro photoconductive carbazole methylene-4H- Adhesive furan capable inden- / T.2-b_7- siv layer thiophene 49000 290 mg 243 mg 46 mg 5.2 g about 12 / rev (1.5 mmol) (0.75 mmol) 1-bromine Il pyrene Il Il It formalde- No. 3 hyd resin about 11 / rev 586 mg 290 mg 5.3 g (2 mmol)

-14-

409828/1112

mg (2 mmol)

130 mg (0.4 mmol) mg 3.9 g

approximately

Poly-N-vinyl carbazole

mg (2 mmol)

2.6.8-trinitrate-4-dicyanomethylene-4H-indene-A7

f · - - - r

Ethiopia

37 mg (0.1 mmol) mg 6.1 g

approximately

1-bromopyrene formal de hydharz

mg (2 mmol)

37 mg (0.1 mmol) mg 5.1 g

approximately

chlorinated poly-N-vinylcarbazole

mg (1.5 mmol)

6.8 Dinitro

4-dicyanome-

ethylene-4H-

inden / T.2-b_7-

Ethiopia

243 mg (0.75 mmol) mg 6.0 g

approximately

+2)

brominated poly-N-No.8 vinyl carbazole

mg (1.5 mmol)

243 mg (0.75 mmol) mg 6.0 g

approximately

⁺ 1) chlorine content. 1 chlorine atom per monomeric unit of poly-N-vinylcarbazole

2) Bromine content 1 bromine atom per two monomeric units of poly-N-vinylcarbazole.

A09828 / 1112

- 15 -

The values for Vpo, E ^ ₂ and E ^ ^ of the photosensitive materials No. 2 to No. 8 were measured by the same method as in Example 1. The values obtained are given in Table III below.

Table III

No. loading Vpo
(V). ' ^E 1/2
(luX'Sek.) ^E V5
(lux sec.) 2 - 505 20.6 61.7 3 - + • 340 24.0 68.6 4th - 1100 14.6 67.1 5 + 800 23.7 . 75.5 6th - 880 26.9 86.9 7th + 900 29.2. 93.2 8th - 660 22.9 69.4 + 560. 14.9 47.7 - 420 32.0 81.0 + 270 57.4 93.2 - 650 18.3 55.0 + 490 22.5 .60.1 - 630 19.9 60.0 + 490 23.3 67.7

In the examples given above, only 6.8-dinitro-4-dicyanomethylene-4H-indene / T.2-b7-thiophene were used (Formula V) and 2.6.8-trinitro-4-dicyanomethylene-4H-indene- / T. 2-b_7-thiophene

-16- 409828/1112.

(Formula VI) used as a sensitizer, but similar values for VpO, E ₁ , ^ and Ej Aj as in Tables .. I and III can be obtained if 4-dicyanomethylene-4H-indene- / T <, 2 -b_7-thiophene or its derivatives, as indicated in the formulas I to IV, instead of the above-mentioned 4-dicyanomethylene-4H-indene- / To2-bJ7_thiophenderivate in an amount of 0.01 to 1 mol per monomeric unit of poly-N- vin'ylcarbazole, chlorinated or brominated poly-H-vinylcarbazole or 1-bromopyrene formaldehyde resin is used.

Similar results are obtained with the corresponding 8-dicyanomethylene-8H compounds with the same preparations.

Electrophotographic photosensitive materials sensitive to visible light can be prepared with organic photoconductive compounds which are not sensitive to visible light by adding a certain amount of 4-dicyanomethylene-4H-indene / T _e 2-b / -thiophene or 8-dicyanomethylene- 8R- ± nen / 2. 1-bJ7-thiophene or its derivatives are added to the organic photoconductive compounds.

The 4-dicyanomethylene-4H-indene / T. 2-bJ7-thiophene compounds of this invention are new. -.

- ι

4-dicyanomethylene-4H-indene / T.2-b7-thiophene and its derivatives can be prepared using the methods described below.

-17-409828 / 1112

(D

Benzoic acid ester derivative

LA "

(2)

Thiophene derivative

acid e ester derivative

where the radicals R ₁ and R _{2 are} hydrogen atoms or nitro groups, X is a chlorine, bromine or iodine atom and R is a lower alkyl group with 1 to 4 carbon atoms from 50 ⁰ G 'to 15O ⁰ G carried out.

GOOR

GOOH.

(3)

U)

2-cc-thienylbenzoic acid-T derivative

where R ^, Ro and R have the same meaning as above »The reaction shown above is carried out in an aqueous solution of HaOH at a temperature of 15 to 6O ⁰ G,

-18-

0 9 8 2 8/1112

2384763

Indenthiophene derivative

The ring closure indicated above is carried out in the presence of polyphosphoric acid Lei one. Temperature from 70 to 150 ° C through ' guided.

(6) indenthiophene derivative

The nitration shown above, in the presence of concentrated HgSO _2, at a tempera ^door conducted from 0 to 15 ⁰ C.

+ H ₂ O

GG (6) - Di G j-äJi ο me thy 3- e η- 4 H-inden ^ T. ^ b / ^ - thiophene or its derivatives

0 ^^ 28/1112

The reaction shown above is carried out in the presence of piperidine in a solution of tetrahydrofuran

The novel compounds of Formula 6 of the present invention are particularly suitable as sensitizers for organic photoconductive compounds, such as poly-N-vinylcarba * - zol ο

The process for the preparation of 6.8-dinitro-4-dicyanomethylene-4H-indene / T.2-b_7_-bhiophen and 2.6.8-trinitro-4-dicyanomethylene-4H-indene ^ To2-b7-thiophene are described in detail below

13 g (0-05 mol) of methyl 2-chloro-3,5-dinitrobenzoate (melting point 193 to 196 ⁰ C, formula 1 as stated above) and 21 g (0.1 mol) of 2-iodothiophene (boiling point 71 to 73 ° C / 16 Torr, formula 2) was dissolved in 100 ml of dimethylformamide and heated to a temperature of 7O Lösung.bei ⁰ G. To this solution was added 20 g of active copper powder (prepared by the method as described in Journal of American Chemical Society Volume 55, page 4219 (1933) by E ₀ C. Kleider and R, Adams .described) over 10 minutes, after which the solution is stirred at a temperature of 70 ° C. for 50 minutes. After cooling, the reaction product was poured into 500 ml of cold water. The precipitate thus formed was filtered off and washed with water. After the water was removed from the precipitate, the precipitate was added to 500 ml of acetone. After further stirring, the solution was filtered

4 0 9 8 2 8/1112 ~ ²⁰ ~

trotted. The filtrate was treated with activated charcoal and then filtered. The piltrate was condensed to obtain a crude product. 15.1 g of yellowish crystalline product (melting point 134 Ms 135 ° C.) were obtained in 85% yield after recrystallization of the crude product from ethyl alcohol

This product was methyl 2 thienyl 3 »5-dinitrobenzoate

(Formula 3).

Analysis:

G ( ^c / i) H (? O) "N (yo) S {'-fa)

Calculated for
O ₁ ^ H ₈ E ₂ OgS 46.75 2.61 9.09 10.41

Found 46.86 2.60 9.02 10.61

The presence of the carbonyl group was detected by means of infrared absorption at 1730 cm ^

23.6 g of the methyl 2-thienyl ^^ - dinitrobenzoate obtained in this way (Formula 3) were dissolved in 100 ml of dioxane and an aqueous solution of NaOH (6 g NaOH in 200 ml of water), after which the mixture was stirred for a further 3 hours.

A small amount of activated charcoal was added to this solution and the solution was filtered. Cold water was added to the filtrate and it was neutralized with 6H-HCl with cooling, whereby a yellowish crystalline product was obtained. The crystalline product was filtered off, washed with water and then dried. The crude product (melting point 171 to 172 ^° C.) was obtained in a yield of 21.5 g.

409828/1 1 12 -21-

A yellowish crystalline pr.od.ukt (melting point 172.5 173.5 ^Q C) was obtained by recrystallization of the crude product from benzene. This product was analyzed as 2-tx -thienyl ^. ^ - dinitrobenzoic acid (formula 4) by means of elemental analysis. ■ '

Analysis: for
t 0 ( 90 2 , 06. N (Ji) S. (Ji) Calculated ' 44, 65 2 , 10 9.52 10 , 90 Found 44, "9.65 10 , 72

The presence of the carbonyl and hydroxyl groups was determined by means of

—1 ■ —1 Infrared absorption detected at 1730 cm and 3000 cm, respectively.

The 2-oC-thienyl-3.5- to 2 g <linitrobenzoesäure (Formula 4) was added 60 g of polyphosphoric acid, and the mixture was heated to a temperature of 130-140 ⁰ C. After cooling, the reaction mixture was poured into 200 ml of cold water. The precipitate thus formed was filtered off and washed with an aqueous solution of sodium carbonate and water and then dried. 18 g of crude product (melting point 206 to 207.5 ⁰ C) was obtained in 95 ^ IEEI "yield. The orange-brown crystalline product (melting point 209.5 to 210.0 ⁰ C) was obtained by recrystallization of the crude product from tetrahydrofuran ·. This Product was identified as a new compound, namely 6.8-dinitro-4H-inden- / T.2-b7-thiophen-4-one (formula 5), by means of elemental analysis.

-22- 409828/1 112

Analysis: for
O ₅ S G (^) H 46 N (#) O \ / 0 y Calculated 47.85 1, 57 10.11 11.61 Found 47.65 1, 10.01 ■ , 11.62

The presence of the carbonyl group was confirmed by infrared absorption detected at 1750 cm.

1.5 S 6.8-Dinitro-4H-inden- / T.2-b7-thiophen-4-one (formula 5) were dissolved in 50 ml of concentrated H ^ SO ^. and to this solution was added dropwise with stirring 5 ^m l HNO ^ (spec.

Weight 1.58) at a temperature of 5 to 10 ⁰ O for 50 minutes. Stirring was continued at this temperature for 1.5 hours. This solution was poured into 200 ml of cold water * A yellowish crystalline product was separated from the solution. The crude product was filtered and washed with water and then dried. 1.4 g of yellowish naidelähnliches crystalline product (melting point 225 to 225.5 ⁰ C) was obtained in 80.5 #> yield after recrystallization of the crude product from dioxane and ethyl alcohol. This product was identified as the new compound 2.6.8-rtrinitro-4R-inden- / T.2-b7-thiophen-4-one (formula 6) by means of elemental analysis.
Analysis:

Calculated for
O ₇ S 41 , 16 0 , 95 ' 13-, 08 9 , 98 Found 40 , 90 1 , 52 ■ 12, 90 10 , 25

-23- 4098 2 87111ε

The presence of the carbonyl group was confirmed by infrared absorption detected at 1730 cm.

8 g 6.8-dinitro-4H-inden / T.2-b_7tliiophen- ^£ l-one (Formula 5) and 3.8 g Ilalonitril were dissolved in 150 ml of tetrahydrofuran and to this solution "was added a few Tropfeh piperidine under reflux. After refluxing for further 20 minutes, tetrahydrofuran was distilled off under reduced pressure. The residue was washed with methyl alcohol. It was 4.4 g. 6.8-dinitro-4-dicyanomethylene-4H-inden / T.2-b_7-thiophene (Formula V, melting point 244 to 245.5 ⁰ C ") was obtained by recrystallization of the residue from dioxane ■ ■..

Analysis: for c ( Si) 1, *) 17th *) B ( *) Calculated 51 , 85 1, 24 17th , 28 9, 89 Found 51 , 82 01 , 62 9, 80

The presence of the cyano group was confirmed by infrared absorption at 2230 cm " ¹ .

10 g - ^. E-e-trinitro- ^ H-inden- ^ T. ^ - by-thioplien - ^ - on (formula 6) and 4 g of malonitrile were dissolved in a mixture of 200 ml of tetrahydrofuran and 200 ml of methyl alcohol and added to this A few drops of piperidine were added to the solution under reflux. After maintaining the reflux for a further 20 minutes, the separated crystals were filtered off from the solution. After crystallization from a mixture of

Α09828 / 1Π2. ■ ~ ^U ~

Dioxane and acetonitrile gave 8 g of 2,6,8-trinitro-4-dicyanomethylene-4H ~ indene- / T _e 2-b7-thiophene (formula VIj melting point above 30 ° C) as red crystals in plate form. Analyzes - / ■ ·

Calculated
14 3 .5 '{ for C.
45 , 33 H (Ji)
0.82 * (*).
'18, 97 .- S.
.8th , .68 Found 45 .85 0.84 19.04 9 , 02

The presence of the cyano group was determined by means of infrared absorption detected at 2220 cm ~.

The corresponding e-dicyanomethylene SH compounds are also new. They are produced by reacting malononitrile with the corresponding 8H-indene- ^ _O i-bT'-thiophen-8-ones. The starting materials are produced according to the processes described in:

MacDowell and others, J.OrgoCheiüo 32, 2441 (196?)

Dubard and others, Academy Science Sere. C. 271 (4) 311 (1970).

Patent claims:

-25-409828 / 1112

Claims (1)

Patent claims: 1. Elektrophotographisch.es light-sensitive material with a photoconductive layer which is formed on a photoconductive support, the photoconductive Layer an organic photoconductive monomer or an organic photoconductive polymer and a sensitizing Combination of the following general formulas contains. NC-C-CN '■■■' ■ (A) (B) UC-O-CIT in which the radicals R ₁ , R _{2 are} > or nitro groups. and Rg hydrogen atoms 2. Elektrophotographisch.es light-sensitive material according to Claim 1, characterized in that that the sensitizing compound is used in an amount of about 0.01 to about 1.2 moles per mole of organic photoconductive Monomeric or organic per monomeric unit -26- 409828/1112 photoconductive polymer is present » 3. Electrophotographic photosensitive material according to claim 1, characterized in that the sensitizing compound is 6 ₀ 8-dinitro-4-dicyanomethylene-4H-indene- / T.2-b / -thiophene. 4. Electrophobographic photosensitive material according to claim 1, characterized in that the sensitizing compound is 2.6.8-trinitro-4-dicyanomethylene-4H-indene / Te2-b / -thiophene _o 5. Electrophotographic photosensitive material according to Claim 1, characterized in that that the sensitizing compound 2.6-Dinitr'o-S-dicyanomethylene-eH-indene - / ^ ". 1-b / -thiophene is. 6. Electrophotographic photosensitive material according to claim 1, characterized in that the sensitizing compound is 2.4.6-trinitro-8-dicyanomethylene-8H-indene / 2 ₀ 1-b / -thiophene _o 7. Method of making a compound of the following general formulas -27-4-098 28/1 1 1 2 NC-G-GU NC-C-GN (A) in which the radicals R., R ₂ > ^R 3> ^r a>% ^{u: generally <i} % are hydrogen atoms or nitro groups, for which the corresponding thiophen-4-one is reacted with malononitrile. '■' - 8. Compound of the formula: NC-C-CN NC-O-CN (A) wherein the radicals R ^, R ₂ , R ^ _{5 are} R ^, or nitro groups. 4 0 9 8 2 8/1112 (B) c and Rg hydrogen atoms -28- 9 ο 6 ο 8-dinitro-4-dicyanomethylene-4H-indene / To 2-Td / ⁷ -thiophene ΙΟ »2 _e 6o8-trinitro-4-dicyanometiiylen-4H-indene- / T.2-b / ^r thiopheno 11. 2. 6-Dinitro ~ 8-dioyanomethylene-8H-indene- / 2'o i-tZ- 12. 2ο4ο ö-Trinitro-S-dicyanometiiyleij.-eH-inden - / ^. X-Jo / - thiopheiio. 409828/1112