US3600184A - Silver halide photographic materials sensitized with a methine dye having an isoindolo(2,1 - a)benzimidazol -yl moiety - Google Patents

Abstract

PHOTOGRAPHIC SILVER HALIDE EMULSIONS ARE PROVIDED WHICH CONTAIN A METHINE DYE HAVING AN ISOINDOLO(2,1-A) BENZIMIDAZOL-11-YL MOIETY.

Description

United States Patent @fice Int. Cl. G03c 1/08 US. Cl. 96-129 14 Claims ABSTRACT OF THE DISCLOSURE Photographic silver halide emulsions are provided which contain a methine dye having an isoindolo[2,l-a] benzimidazol-l l-yl moiety.

This invention relates to novel photographic materials, and more particularly to new light-sensitive photographic silver halide emulsions containing certain methine dyes, and photographic elements prepared therewith.

It is Well known to extend the spectral sensitivity of silver halide emulsions with various methine dyes. However, it has been found that not all methine dyes give satisfactory sensitizing results. Also, the number that can be used in practice is further limited by the Way in which the dye sensitizer performs when incorporated into silver halide emulsion layers. For example, the clearness of the layers and the sharpness of the images produced therein, as Well as the keeping stability on storage, particularly in regard to freedom from fogging and maintenance of the desired level of selective sensitization, must not be adversely afiected by the added dyes. For the purposes of color photography, it is recognized as being especially important that the dyes used fully meet not only the above requirements, but in addition, provide satisfactory selective sensitivity in the emulsion layers. Relatively, few dyes are known to meet such stringent requirements. Accordingly, it will be evident that there is need in the photographic art for new selectively sensitized materials.

Accordingly, one object of this invention is to provide novel photographic materials.

Another object of this invention is to provide lightsensitive photographic silver halide emulsions containing certain methine dyes.

A further object of this invention is to provide novel photographic elements comprising a support material having thereon at least one layer of the above novel emulsions of the invention.

Other objects of this invention will be apparent from the following disclosure and the appended claims.

In accordance with one embodiment of this invention, photographic silver halide emulsions are provided which contain a methine dye having an isoindolo[2,l-a]benzimidazol-ll-yl moiety.

We have now made the important discovery that methine dyes derived from 5-substituted-1lH-isoindolo [2,1-a] benzimidazolium salts are especially useful spectral sensitizers for light-sensitivity photographic silver halide emulsions. These novel emulsions are characterized by having an extended sensitivity range of about from 5 80 to 700 nm., and even higher in some instances, with maximum sensitivity ranging from about 550 to 650 nm. They are further characterized by good keeping qualities and causing relatively little, if any, fogging in. both fresh and incubated conditions. Also, the images produced therewith are of excellent quality, being clear, sharp and of good density.

In another embodiment of this invention, carbocyanine dyes are provided which comprise first and second nitro- 3,690,184 Patented Aug. 17, 1971 gen containing heterocyclic nuclei joined together by a dimethine or tetramethine linkage; the first of said nuclei being an isoindolo[2,1-a]benzimidazole nucleus joined at the ll-carbon atom thereof to said linkage; and, said second nucleus being of the type used in preparing cyanine dyes joined at a carbon atom thereof to said linkage, to complete said carbocyanine dye.

In still another embodiment of the invention, merocyanine dyes are provided which comprise first and second nitrogen containing heterocyclic nuclei joined together by a methine or trimethine linkage; the first of said nuclei being an isoindolo[2,1-a]benzimidazole nucleus joined at the ll-carbon atom thereof to said nucleus; and, said second nucleus being a ketomethylene nucleus of the type used in merocyanine dyes joined at a carbon atom thereof to said linkage, to complete said merocyanine dye.

In still another embodiment of the invention, benzylidene dyes are provided which comprise two nuclei joined together by a 'rnonomethine or a trimethine linkage; the first of said nuclei being an isoindolo[2,l-a]benzimidazole nucleus joined at the ll-carbon atom thereof to said linkage; and, said second nucleus being a p-dial'kylaminoaryl nucleus, joined at the 4-carbon atom thereof to said linkage, to complete said benzylidene dye.

Particularly useful methine dyes for practicing the invention include those represented by one of the following formulas:

I Ru

e.g., fl-hydroxyethyl, w-hydroxybutyl, etc., an alkoxyalkyl group, e.g., fl-methoxyethyl, w-butoxybutyl, etc., a carboxyalkyl group, e.g., fl-carboxyethyl, w-carboxybutyl, etc., a sulfoalkyl group, e.g., B-sulfoethyl, w-sulfobutyl, etc., a sulfatoalkyl group, e.g., fi-sulfatoethyl, w-sulfatobutyl, etc., an acyloxyalkyl group, e.g., fi-acetoxyethyl, 'y-acetoxypropyl, w-butyryloxybutyl, etc., an alkoxycarbonylalkyl group, e.g., fi-methoxycarbonylethyl, w-ethoxycarbonylbutyl, etc., an aralkyl group, e.g., benzyl, phenethyl, etc., or an aryl group, e.g., phenyl, tolyl, naphthyl, methoxyphenyl, chlorophenyl, etc.; R represents an alkyl group (preferably a lower alkyl containing from 1 to 4 carbon atoms), e.g., methyl, ethyl, propyl, isopropyl, butyl, hexyl, cyclohexyl, decyl, dodecyl, etc.; R represents an aryl group, e. phenyl, tolyl, naphthyl, methoxyphenyl, chlorophenyl, etc.; R and R each represents a hydrogen atom, an alkyl group (preferably a lower alkyl containing from 1 to 4 carbon atoms), e.g., methyl, ethyl, propyl, isopropyl, butyl, hexyl, cyclohexyl, decyl, dodecyl, etc., an alkoxy group, e.g., methoxy, ethoxy, isopropoxy, butoxy, etc., a halogen atom, e.g., chlorine or bromine, and the like; R and R each represents the same or different alkyl group (preferably a lower alkyl containing from 1 to 4 carbon atoms) e.g., methyl, ethyl, propyl, isopropyl, butyl, hexyl, cyclohexyl, decyl, dodecyl, etc.; X represents an acid anion, e.g., chloride, bromide, iodide, thiocyanate, sulfamate, perchlorate, p-toluenesulfonate, methyl sulfate, ethyl sulfate, etc.; Z represents the non-metallic atoms necessary to complete a sensitizing heterocyclic nucleus of the type used in cyanine dyes, containing from 5 to 6 atoms in the heterocyclic ring, which may also include, in addition to the hetero nitrogen atom, a second hetero atom such as oxygen, sulfur, selenium or nitrogen, such as the following nuclei:

a thiazole nucleus, e.g., thiazole, 4-methylthiazo1e, 4-phenylthiazole, S-methylthiazole, S-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4-(2-thienyl)thiazole, benzothiazole, 4-chlorobenzothiazole, S-chlorobenzothiazole, 6-chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole, S-methylbenzothiazole, 6-methylbenzothiazole, S-bromobenzothiazole, 6-bromobenzothiazole, 4-phenylbenzothiazole, 4-methoXybenzothiazole, S-methoxybenzothiazole, 6-methoxybenzothiazole, 5-iodobenzothiazole, 6-iodobenzothiazole, 4- ethoxybenzothiazole, S-ethoxybenzothiazole, tetrahydrobenzothiazole, 5,6-dimethoxybenzothiazole, 5,6-dioxymethylenebenzothiazole, S-hydroxybenzothiazole, 6- hydroxybenzothiazole, naphtho[2,1-d]thiazole, naphtho [1,2-d]thiazole, fi,t-I-naphtho[2,3-d]thiazole, S-methoxynaphtho[2,3 d]thiazole, 5-ethoxynaphtho[1,2 d]thiazole, 8-methoxynaphtho 2, l-d] thiazole, 7-methoxynaphtho [2, l-d] thiazole, 4'-methoxythianaphtheno-7',6', 4,5-thiazole, etc.;

an oxazole nucleus, e.g., 4-methyloxazole, S-methyloxazole, 4-phenyloxazole, 4,5-diphenyloxazole, 4-ethyloxazole, 4,5-dimethoxazole, 5-phenyloxazole, benzoxazole, S-chlorobenzoxazole, S-methylbenzoxazole, 5- phenylbenzoxazole, 6-methylbenzoxazole, 5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, S-methoxybenzoxazole, S-ethoxybenzoxazole, S-chlorobenzoxazole, 6- methoxybenzoxazole, 5 -hydroxybenzoxazole, 6-hydroxybenzoxazole, naphtho [2,1-d] oxazole, naphtho [1,2-d]oxazole, etc.;

a selenazole nucleus, e.g., 4-methylselenazole, 4-phenylselenazole, benzoselenazole, 5-chlorobenzoselenazole, S-methoxybenzoselenazole, 5-hydroxybenzoselenazole, tetrahydrobenzoselenazole, naptho[2,1 d]selenazole, naphtho[1,2-d]selenazole, etc.;

a thiazoline nucleus, e.g., thiazoline, 4-methylthiazoline,

etc.;

a pyridine nucleus, e.g., Z-pyridine, S-methyl-Z-pyridine,

4-pyridine, 3-methyl-4-pyridine, etc.;

a quinoline nucleus, e.g., Z-quinoline, 3-methyl-2-quinoline, 5-ethyl-2-quinoline, 6-chloro-2-quinoline, S-chloro- Z-quinoline, 6-methoxy-2-quinoline, 8-ethoxy-2-quinoline, 8-hydroxy-2-quinoline, 4-quinoline, 6-methoxy-4- quinoline, 7-methyl-4-quinoline 8-chloro-4-quinoline, l-isoquinoline, 3,4-dihydro-l-isoquinoline, 3-isoquinoline, etc; and,

a 3,3-dialkylindolenine nucleus, e.g., 3,3-dimethylindolenine, 3,3-dibutylindolenine, etc.; and

an imidazole nucleus e.g., imidazole, l-alkylimiclazole, l-

alkyl-4-phenylimidazole, 1-alky1-4,5-dimethylimidazole, benzimidazole, l-alkylbenzimidazole, 1-aryl-5,6-dichlorobenzimidazole, 1 alkyl-lH-naphth[2,l-d]imidazole, 1-aryl-3H-naphth[1,2-d]imidazole, l-alkyl-S-methoxylH-naphth[2,l-d]imidazole, etc.; and the like;

and Q represents the nonmetallic atoms necessary to complete a heterocyclic nucleus such as the following nuclei:

a pyrazolinone nucleus (e.g., 3-methyl-l-phenyl-S-pyrazolinone, l-phenyl-S-pyrazolinone, 1-(2-benzothiazolyl)- 3-methyl-5-pyrazolinone, etc.),

an oxindole nucleus (e.g., 1-alkyl-2,3-dihydro-2-oxindoles,

etc.),

a rhodanine nucleus (i.e., 2-thio-2,4-thiazolidinedione series), such as rhodanine, 3-alkylrhodanine (e.g., 3- ethylrhodanine, 3 ethoxycarbonyl-methylrhodanine, 3- allylrhodanine, etc.) or 3-arylrhodanines (e.g., 3-phenylrhodanine, etc. etc.,

a 2-selena-2,4-thiazolidinedione nucleus (e.g., 3-ethyl-2- selena-2,4-thiazolidinedione, etc.),

a 2-thio-2,4-oxazolidinedione nucleus (i.e., those of the 2- thio-2,4(3H,5H)-oxazoledione series) (e.g., 3-ethyl-2- thio-2,4-oxazolidinedione, etc.),

a 2-thio-2,S-thiazolidinedione nucleus (i.e., the 2-thio-2,5 (3H,4H)-thiazoledione series) (e.g., 3-ethyl-2-thio-2,5- thiazolidinedione, etc.),

a 2,4-thiazolidinedione nucleus (e.g., 2,4-thiazolidinedione, 3-ethyl-2,4-thiazolidinedione, 3-phenyl-2,4-thiaz0lidinedione, 3-a-naphthyl-2,4-thiazolidinedione, etc.),

a thiazolidinone nucleus (e.g., 4-thiazolidinone, 3-ethyl-4- thiazolidinone, 2 dicyanomethylene-3-ethyl-4-thiazolidinone, 3-phenyl-4-thiazolidinone, 3-a-naphthy1-4-thiazolidinone, etc.),

a 4-thiazolin-one nucleus (e.g., Z-ethyl-mercapto-4-thiazolinone, 2-alkylphenylamino-4-thiazolinones, 2-diphenylamino-4-thiazolinone, etc.)

a 2(3H)-thiophenone nucleus (e.g., 5-methyl-2(3H)-thiophenone, etc.),

a 2-imino-2,4-oxazolinone (i.e., pseudohydantoin) nucleus,

a 2,4-imidazolinedione (hydantoin) nucleus (e.g., 2,4- imidazolinedione, 3-ethyl-2,4-imidazolinedione, 3-phenyl-2,4-imidazolinedione, 3-a-naphthyl-2,4-imidazolinedione, 1,3-diethyl-2,4-imidazolinedione, 1-ethyl-3-anaphthyl-2,4-imidazolinedione, 1,3-diphenyl-2,4-imidazolinedione, etc.),

a 2-thio-2,4-imidazolinedione (i.e., 2-thiohydantoin) nucleus (e.g., 2-thio-2,4-imidazolinedione, 3-ethyl-2-thio- 2,4imidazolinedione, 3-phenyl-2-thio-2,4-imidazolinedione, 3-u-naphthy1-2*thio-2,4-imidazolinedione, 1,3-diethyl-2-thio-2,4-imidazolinedione, 1-ethyl-3-phenyl-2- ethyl 2 thio-2,4-imidazolinedione, 1-ethyl-3-phenyl-2- thio-2,4-imidazolinedione, 1-ethyl-3-a-naphthyl-2-thio- 2,4-imidazolinedione, 1,3 diphenyl-2-thio-2,4-imidazolinedione, etc.),

a S-imidazolinone nucleus (e.g., 2-n-propylmercapto-5- imidazolinone, etc.), etc.

(especially a heterocyclic nucleus containing 5 or 6 atoms in the heterocyclic ring, 3 or 4 of said atoms being carbon atoms, 1 of said atoms being a nitrogen atom, and 1 of said atoms being selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom).

The carbocyanine dyes defined by Formula I above are especially useful spectral sensitizers for negative type silver halide emulsions, and are the preferred class of sensitizers in this invention. They are conveniently prepared, for example, by heating a mixture of (1) an isoindolo[2,l-a]benzimidazolium salt of the formula:

wherein R R R and X are as previously defined, and (2) 'a heterocyclic salt of the formula:

wherein m, L, R X and Z are as previously defined, and R represents a hydrogen atom or an acyl group, e.g., acetyl, propionyl, etc., in approximately equimolar proportions, in the presence of a basic condensing agent such as a trialkylamine, e.g., triethylamine, etc., piperidine, N- methylpiperidineyetc, in ,a solvent medium such as pyridine, acetic anhydride, etc. The dyes are then separated from the reaction mixtures, and purified by one or more recrystallizations from appropriate solvents such as ethanol, mixtures of ethanol and dimethylformamide, pyridine, and the like.

The merocyanine dyes defined by Formula II above are readily prepared by heating a mixture of (1) a compound selected from Formula IV above, and (2) a heterocyclic compound of the formula:

wherein d, L, R and Q are as previously defined, in approximately equimolar proportions, in the presence, of a basic condensing agent, and the pure dye recovered in generally similar manner as described above the preparation of dyes of Formula I above.

The benzylidene dyes defined by Formula III above are advantageously prepared by heating a mixture of (1) a compound selected from Formula IV above, and (2) a compound of the formula:

wherein g, R, and R are as previously defined, in approximately equimolar proportions, in the presence of a basic condensing agent, e.g., piperidine, in a solvent medium such as an alkanol, e.g., ethanol, etc. The purified dye is obtained by separation of the crude dye from the reaction mixture followed by one or more recrystallizations there of from appropriate solvents such as methanol, mixtures of ethanol and dimethylformamide, and the like.

The intermediate isoindolo[2,1-a]benzimidazole (Bistrzycki and Schmutz, Ann. 415, 1 (1917)) with appropriate quaternizing agents, e.g., methyl tosylate, ethyl tosylate, butyl tosylate, dimethyl sulfate, etc. Further details for their preparation can be had by reference to copending appilcation of G. Irick, U.S. Ser. No. 642,238 filed May 29, 1967, wherein such intermediates are described and claimed, together with a number of carbocyanine and benzylidene dyes prepared therewith, which latter are indicated as being useful for the specific purpose of dyeing fibers, yarns and fabrics.

In the preparation of negative silver halide photographic emulsions, the dyes of the invention are advantageously incorporated in the washed, finished silver halide emulsion and should, of course, be uniformly distributed throughout the emulsion. The methods of incorporating dyes and other addenda in emulsions are relatively simple and well known to those skilled in the art of emulsion making. For example, it is convenient to add them from solutions in appropriate solvents, in which case the solvent selected should be complextely free from any deleterious effect on the ultimate light-sensitive materials. Methanol, isopropanol, pyridine, water, etc., alone or in admixtures, have proven satisfactory as solvents for this purpose. The type of silver halide emulsions that can be sensitized with the dyes of the invention include any of those prepared with hydrophilic colloids that are known to be satisfactory for dispersing silver halides, for example, emulsions comprising natural materials such as gelatin, albumin, agaragar, gum arabic, alginic acid, etc. and hydrophilic synthetic resins such as polyvinyl alcohol, polyvinyl pyrrolidone, cellulose ethers, partially hydrolyzed cellulose acetate, and the like.

The binding agents for the emulsion layer of the photographic element can also contain dispersed polymerized vinyl compounds. Such compounds are disclosed, for example, in US. Pats. 3,142,568; 3,193,386; 3,062,674 and 3,220,844 and include the water insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates and the like.

The types of silver halide emulsions that can be sensitized with the new dyes of this invention include any of the conventional emulsions prepared with light-sensitive silver salts including silver chloride, silver bromide, silver iodide, silver chlorobromide, silver bromoiodide, silver chlorobromoiodide, etc. The concentration of the new dyes in the emulsion can vary widely, e.g., from about 5 to about mg. per liter of flowable emulsion. The specific concentration will vary according to the type of lightsensitive material in the emulsion and the effects desired. The suitable and most economical concentration for a given emulsion will be apparent to those skilled in the art upon making the tests and observations customarily used in the art of emulsion making.

To prepare a gelatin-silver halide emulsion sensitized with one of the dyes of this invention, the following procedure is satisfactory. A quantity of the dye is dissolved in a suitable solvent and a volume of this solution containing from 5 to 100 mg. of dye is slowly added to about one liter of a gelatin-silver halide emulsion. With most of the dyes, about from 5 to 20 mg. of dye per liter of emulsion suflices to produce the maximum sensitizing effect with the ordinary gelatin-silver bromide (including bromoiodide and chlorobromide) emulsions. With fine grain emulsions, which include most of the ordinarily employed gelatin-silver chloride emulsions, somewhat larger concentrations of dye may be necessary to obtain the optimum sensitizing effect. While this procedure has dealt with emulsions comprising gelatin, it will be understood that these remarks apply generally to any emulsions wherein part or all of the gelatin is substituted by another suitable hydrophilic colloid, such as previously mentioned. It will also be understood that the above description is lntended to be illustrative and should not be construed as limiting my invention in any sense since it is apparent that the new dyes can be incorporated by other methods 1n many of the photographic silver halide emulsions and hydrophilic colloid layers customarily employed in the art. For instance, the dyes can be incoporated by bathing a plate or film bearing an emulsion layer in a solution of one of the dyes in an appropriate solvent. Bathing methods, however, are not normally preferred.

The novel emulsions of this invention may be coated on any suitable photographic support, such as glass, film base such as cellulose acetate, cellulose acetate butyrate, polyesters such as poly(ethylene terephthalate), paper, baryta coated paper, polyolefin coated paper, e.g., polyethylene or polypropylene coated paper, which may be electron bombarded to promote emulsion adhesion, to produce the novel photographic elements of the invention.

The following examples illustrate the preparation of a number of specific methine dyes that are useful for preparing the novel emulsions and elements of the invention.

7 EXAMPLE 1 3',5-diethyl-1l-isoindolo[2,1-a]benzimidazolooxacarbocyanine iodide ethyl 11H isoindolo[2,1-a]benzimidazolium tosylate (1.22 g., 3 mmol.), 2-acetanilidoviny1-3-ethylbenzoxazolium iodide (1.30 g., 3 mmol.), triethylamine (0.6 ml.) and pyridine (7 ml.) are refluxed for 5 minutes. The dye is precipitated by the addition of ether and the syrupy residue washed with ether. It crystallized when stirred with ethanol. After chilling it is filtered off and dried. The yield is 0.59 g. (37%). After two recrystallizations from methanol, the pure dye melts at 298-299 C.

dec.

EXAMPLE 2 3 ,5'-diethyl-ll-isoindolo[2,1-a1benzimidazolothiacarbocyanine iodide S =CHCH:

GEN r l (3 11 5 ethyl 11H isoindolo[2,l-a]benzimidazolium tosylate (1.22 g., 3 mmol.), 2-acetanilidovinyl-3-ethylbenzothiazolium iodide (1.35 g., 3 mmol.), triethylamine (0.6 ml.) and pyridine (7 ml.) are refluxed for 5 min. The dye is isolated as in Example 1. The yield is 1.41 g. (86% Twice recrystallized from methanol, the dye melts at 296-297 C., dec.

EXAMPLE 3 5'-ethy1-1,3,3-trimethylindo-11-isoindolo[2,1-a] benzimidazolocarbocyanine iodide H3 CCH;

GEN:

5 ethyl 11H isoindolo[2,1-a]benzimidazolium tosylate (1.22 g., 3 mmol.), 2-acetanilidovinyl-1,3,3-trimethyl-3H-indolium iodide (1.34 g., 3 mmol.), triethylamine (0.6 ml.), and pyridine (7 ml.) are refluxed for 5 minutes. The dye is isolated as in Example 1. The yield is 0.94 g. (57%). After successive recrystallizations from methanol and ethanol, the dye melts at 301-302 C. dec.

:EXAMPLE 4 5,6-dichloro-1,3,5'-triethylbenzimidazolo-11'-isoindolo- [2,1-a]benzimidazolocarbocyanine iodide $2 5 Cl N Cl i J: CH CII= e EXAMPLE 5 3 ',5-diethyl-4,5-benzo-1l-isoindolo[2,1-a]benzimidazolothiacarbocyanine tosylate 5-ethyl-11H-isoindolo[2,l-a]benzimidazoliurn tosylate (1.63 g., 4 mmol.), 5-acetanilidomethylene-3-ethylrhodathiazolium tosylate (2.01 g., 4 mmol.), acetic anhydride (0.6 ml.), triethylamine (1.1 ml.) and pyridine (10 ml.) are refluxed together for 8 minutes. The dye is isolated as in Example 1. The yield is 1.99 g. (77%). Twice recrystallized from ethanol, the purified dye melts at 285- 286 C.

I 9 I? 2 5 I 02115 EXAMPLE 6 3-ethy1-5-[ (S-ethylisoindole[2,1-a]benzimidazol-l 1- y1)methylene/rhodanine 5-ethyl-11H-isoindolo[2,1-a]benzimidazolium tosylate (1.63 g., 4 mmol.), 5-acetanilidomethylene-3-ethylrhodanine (1.22 g., 4 mmol.), acetic anhydride (0.4 ml.), triethylamine (1.1 ml.) and pyridine (10 ml.) are refluxed together for 7 minutes and cooled. The dye is precipitated by the addition of 10 ml. methanol, filtered 01f, and dried. The yield is 0.53 g. (33%). After two recrystallizations from pyridine and one from dimethylformamide, the pure dye melts at 275-276 C., dec.

EXAMPLE 7 1 1-p-dimethylaminobenzylidene-S-ethyl-11H- isoindolo [2,1-a]-benzimidazolium iodide S-ethyl-l1H-isoindolo[2,1-a]benzimidazolium tosylate (1.63 g., 4 mmol.), pdimethylaminobenzaldehyde (0.60 g., 4 mmol.), piperidine (6 drops) and ethanol (10 ml.) are refluxed for 10 minutes and chilled. The dye is thrown out with ether. Because it is necessary to convert to the iodide, the precipitate is redissolved in ethanol (20 ml.) and precipitated by 10 ml. of an aqueous solution of sodium iodide (0.60 g., 4 mmol.). The mixture is heated to boiling and chilled, and filtered. The dye is obtained EXAMPLE 8 1 1-p-dimethylaminocinnamylidine-S-ethyl-1lH-isoindolo I [2,1-a]benzimidazolium iodide 7 5,-ethy1-1lH-isoindolo[2,1-a1benzimidazolium tosylate (2.03 g., mmol.), p-dimethylaminocinnamaldehyde (0.92 g., 5.25 mmol.), piperidine (5 drops), and ethanol ml.) are refluxed for 5 minutes. An ethanolic solution of sodium iodide (0.75 g.) is added to precipitate the dye. It is filtered off, washed with ethanol and Water, and dried.

The individual dyes dissolved in suitable solvents are The yield is 0.60 g. (23%). Twice recrystallized from a mixture of dimethylformamide and ethanol, it melts at 299-300 C.

The following example illustrates the preparation and the testing of light-sensitive photographic silver halide emulsions and elements of the invention containing therein the specific dyes of the preceding Examples 1-8 as spectral sensitizers.

EXAMPLE 9 The individual dyes dissolved in suitable solvents are added to separate portions of either a silver bromoiodide emulsion containing 0.77 mole percent iodide or a silver chlorobromide emulsion containing 40 mole percent bromide as indicated in Table 1 below, and at the indicated concentrations. After digestion at 52 C. for 10 minutes, the emulsions in each case are coated at a coverage of 432 mg. of silver per square foot and 11190 mg. of gelatin per square foot on a cellulose acetate film sup port. A sample of each coating is exposed toa wedge spectrograph, and processed in Kodak D-19 developer which has the composition:

1 G. N-methyl-p-aminophenol sulfate 2.0 Sodium sulfite (anhydrous) 90.0 Hydroquinone 8.0 Sodium carbonate (monohydrate) 52.5 Potassium bromide 5.0 Water to make 1.0 liter.

and then fixed, washed and dried. The sensitizing results are shown in the following table.

TABLE 1.SENSITIZING DATA Dye concen- Emulsion tration, g./m. type silver sensitizing maximum (nm.)

sensitizing range Dye of Example None No sensitization Control g1? 10 these too will function in generally similar manner as useful spectral sensitizers for the preparation of other of the novel emulsions and elements of the invention.

Typical examples of such other dyes include, for example, 3,7-dichloro 3',5 diphenyl-ll-isoindolo[2,1 a] benzimidazolo-oxacarbocyanine salt (e.g., the chloride, bromide, iodide, perchlorate, p toluenesulfonate, etc. salts); l',5-diethyl-3,7-dimethoxy 11 isoindolo[2,l-a] benzimidazolo-4-dicarbocyanine salt (e.g., the chloride, bromide, iodide, perchlorate, p toluenesulfonate, etc. salts) 3,3,5,7,-tetraethyl-1 l-isoindolo [2,1-a] benzimidazoloselenacarbocyanine salt (e.g., the chloride, bromide, iodide, perchlorate, p-toluenesulfonate, etc. salts); l-phenyl-5- 5 -phenylisoindol [2,1 a]benzirnidazol-11-yl)allylidene]-2-thiohydantoin; 3-ethyl 5 [5,7-diethylisoindolo- [2,1 a]-benzimidazol-llyl)allylidene]-2-thio-2,4-oxazolidinedione; .1 l-p-dibutylaminobenzylidene-S -ethyl-i1 lH-isoindolo[2,l-a]benzimidazolium salt (e.g., the chloride, bromide, iodide, perchlorate, p-toluenesulfonate, etc. salts); and the like.

Photographic silver halide emulsions containing the sensitizing dyes of this invention can also contain other addenda such as chemical sensitizers, e.g., sulfur sensitizers (e.g., allyl thiocarbamide, thiourea, allylisothi cyanate, cystine, etc.), selenium and tellurium sensitizers. various gold compounds (e.g., potassium chloroaurate. auric trichloride, etc.) (see US. patents to W.D. Baldsiefen, No. 2,540,085, issued Feb. 6, 1951; .R. E. Damschroder, No. 2,597,856, issued May 27, 1952; and H. C. Yutzy et al., US. Patent No. 2,597,915, issued May 27, 1952), various palladium compounds, such as palladium chloride (W. D. Baldsiefen, US. Patent No. 2,540,086, issued Feb. 6, 1951), potassium chloropalladate (R. E. Staulfer et al., US. Patent No. 2,598,079, issued May 27, 1952), etc., or mixtures of such sensitizers; antifoggants such as ammonium chloroplatinate (A. P. H. Trivelli et al., US. Pat. No. 2,566,263, issued Aug. 28, 1951); benzotriazole, nitrobenzimidazole, S-nitroindazole, bermidine, mercaptans, etc. (see Mees, The Theory of the Photographic Process, MacMillan Pub., Revised Edition 1954, page 677), or mixtures thereof.

The photographic silver halide emulsions and the other layers present in the photographic elements made according to the invention can also be hardened with any suitable hardener, including aldehyde hardeners such as formaldehyde, and mucochloric acid, aziridine hardeners, hardeners which are derivatives of dioxane, oxypolysaccharides such as oxy starch or oxy plant gums,'and the like. The emulsion layers can also contain additional additives, particularly those known to be beneficial in photographic emulsions, including, for example, lubricating materials, stabilizers, speed increasing materials, absorbing dyes, plasticizers, and the like. These photographic emulsions can also contain in some cases additional spectral sensitizing dyes. Furthermore, these emulsions can contain color forming couplers or can be developed in solutions containing couplers or other color generating materials. Among the useful color formers are the monomeric and polymeric color formers, e.g., pyrazolone color formers, as well as phenolic, heterocyclic and open chain couplers having a reactive methylene group. The color forming couplers can be incorporated into the photographic silver halide emulsion using any suitable technique, e.g., techniques of the type shown in Jelley et al., US. Patent 2,322,027, issued June 15, 1943, Fierke et al., US. Patent 2,801,171, issued July 30, 1957, Fisher U.S. Patents 1,055,155 and 1,102,- 028, issued Mar. 4, 1913 and June 30, 1914, respectively, and Wilmanns US. Patent 2,186,849, issued Jan. 9, 1940. They can also be developed using incorporated developers such as polyhydroxybenzenes, aminophenols, 3-pyrazolidomes, and the like.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and 1 1 scope of the invention as described hereinabove, and as defined in the appended claims.

We claim:

1. A photographic silver halide emulsion containing at least one carbocyanine dye selected from those comprising first and second nitrogen containing heterocyclic nuclei joined together by a linkage selected from the group consisting of a dimethine linkage and a tetramethine linkage; the first of said nuclei being an isoindolo[2,l-a]benzimidazole nucleus joined at the 11-carbon atom thereof to said linkage; and said second nucleus being of the type used in cyanine dyes employed in negative silver halide emulsions, said nucleus being joined at a carbon atom thereof to said linkage, to complete said carbocyanine dye.

2. A photographic silver halide emulsion containing at least one merocyanine dye selected from those comprising first and second nitrogen containing heterocyclic nuclei joined together by a linkage selected from the group consisting of a monomethine linkage and a trimethine linkage; the first of said nuclei being an isoindolo[2,1-a]benzimidazole nucleus joined at the ll-carbon atom thereof to said nucleus; and said second nucleus being a ketomethylene nucleus of the type used in merocyanine dyes employed in negative silver halide emulsions, said nucleus being joined at a carbon atom thereof to said linkage, to complete said merocyanine dye.

3. A photographic silver halide emulsion containing at least one benzylidene dye selected from those comprising first and second nuclei joined together by a linkage selected from the group consisting of a monomethine linkage and a trimethine linkage; the first of said nuclei being an isoindolo[2,1-a1benzimidazole nucleus joined at the 11- carbon atom thereof to said linkage; and said second nucleus being a p-dialkylaminoaryl nucleus joined at the 4- carbon atom thereof to said linkage, to complete said benzylidene cyanine dye.

4. A photographic silver halide emulsion containing at least one methine dye selected from those having one of the following formulas:

wherein n, m, d and g each represents a positive integer of from 1 to 2; L represents a methine linkage; R and R each represents a member selected from the group consisting of an alkyl group and an aryl group; R and R each represents a member selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group and a halogen atom; R and R each represents an alkyl group; Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the type used in cyanine dyes employed in negative silver halide emulsions, said nucleus having from 5 to 6 atoms in the heterocyclic ring; and Q represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the type used in merocyanine dyes employed in negative silver halide emulsions, said nucleus containing 5 atoms in the heterocyclic ring, 3 of said atoms being carbon atoms, 1 of said atoms being a nitrogen atom, and 1 of said atoms being selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom.

5. A photographic emulsion in accordance with claim 4 containing a photographic color former.

6. A photographic silver halide emulsion containing at least one carbocyanine dye selected from those represented by the formula:

wherein n and In each represents a positive integer of from 1 to 2; L represents a methine linkage; R and R each represents a member selected from the group consisting of an alkyl group and an aryl group; R and R each represents a member selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group and a halogen atom; X represents an acid anion; and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the type used in cyanine dyes employed in negative silver halide emulsions.

7. A photographic silver halide emulsion in accordance with claim 6 in which said 11 of said dye is 1 and said Z of said dye represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of a thiazole nucleus, an oxazole nucleus, at selenazole nucleus, a 3,3-dialkylindolenine nucleus and an imidazole nucleus.

8. A photographic silver halide emulsion containing at least one merocyanine dye selected from those represented by the formula:

wherein said d represents a positive integer of from 1 to 2; L represents a methine linkage; R represents a member selected from the group consisting of an alkyl group and an aryl group; R and R each represents a member selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group and a halogen atom; and Q represents the non-metallic atoms necessary to complete a. heterocyclic nucleus of the type used in merocyanine dyes employed in negative silver halide emulsions,- said nucleus containing 5 or 6 atoms in the heterocyclic ring, 3 or 4 of said atoms being carbon atoms, I of said atoms being a nitrogen atom, and 1 of said atoms being selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom. I

13 9. A photographic silver halide emulsion in accordance with claim 8 in which said n of said dye is 1 and said Z of said dye represents the non-metallic atoms necessary to complete a rhodanine nucleus.

10. A photographic silver halide emulsion containing at least one benzylidene dye selected from those represented by the formula:

3',5-diethyl-1l-isoindolo[2,l-a]benzimidazolo-oxacarbocyanine iodide,

3,5-diethyl-1l-isoindolo[2,l-a]benzimidazolothiacarbocyanine iodide,

1 4 5'-ethyl-,3,3-trimethylindo-1 l-isoindolo [2,1-a]benzimidazolocarbocyanine iodide, 5 ,6-dichloro- 1,3,5 -triethylbenzimidazolo-1 l-isoindolo- [2,1-a]benzimidazolocarbocyanine iodide,

3 ,5-diethyl-4',5-benzo-11-isoindolo[2,1-a]benzimidazolothiacarbocyanine tosylate,

3-ethyl-5-[(5-ethylisoindole[2,1-a]benzimidazolo-1l-yl) methylenehhodanine,

1 1-p-dimethylaminobenzylidene-S-ethyl-1 lH-isoindolo- [2,1-a1benzimidazolium iodide and 1 1-p-dimethylaminocinnamylidene-S-ethyl-1 lH-isoindolo- [2,1-a]benzimidazolium iodide.

12. A photographic element comprising a support having thereon at least one layer containing a photographic silver halide emulsion of claim 1.

13. A photographic element comprising a support having thereon at least one layer containing a photographic silver halide emulsion of claim 4.

14. A photographic element comprising a support having thereon at least one layer containing a photographic silver halide emulsion of claim 11.

References Cited UNITED STATES PATENTS 3,243,298 3/1966 Libeer et a1. 96105 J. TRAVIS BROWN, Primary Examiner US. Cl. X.R.