US3582343A - Direct positive silver halide emulsions containing a 5 nitro -2- arylindole nucleus - Google Patents

Direct positive silver halide emulsions containing a 5 nitro -2- arylindole nucleus Download PDF

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US3582343A
US3582343A US754965A US3582343DA US3582343A US 3582343 A US3582343 A US 3582343A US 754965 A US754965 A US 754965A US 3582343D A US3582343D A US 3582343DA US 3582343 A US3582343 A US 3582343A
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nitro
silver halide
emulsion
direct positive
emulsions
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US754965A
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John D Mee
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Eastman Kodak Co
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Eastman Kodak Co
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
    • C09B23/00—Methine or polymethine dyes, e.g. cyanine dyes
    • C09B23/02—Methine or polymethine dyes, e.g. cyanine dyes the polymethine chain containing an odd number of >CH- or >C[alkyl]- groups
    • C09B23/06—Methine or polymethine dyes, e.g. cyanine dyes the polymethine chain containing an odd number of >CH- or >C[alkyl]- groups three >CH- groups, e.g. carbocyanines

Definitions

  • This invention relates to novel photographic materials, and more particularly to a new class of cyanine dyes, and to new and improved direct positive photographic silver halide emulsions containing one or more of these new dyes.
  • an object of this invention to provide a new class of cyanine dyes which overcome the shortcomings of the above mentioned prior art dyes. Another object is to provide novel direct positive photographic silver halide emulsions, and more particularly fogged direct positive emulsions, containing one or more of the new cyanine dyes of this invention. Another object of this invention is to provde novel emulsions as above containing, in addition, a color former, Another object of this invention is to provide photographic elements comprising a support having thereon at least one layer containing a novel direct positive emulsion of this invention. Another object of this invention is to provide methods for preparing such novel dyes and photographic materials of this invention. Other objects of this invention will be apparent from this disclosure and the appended claims.
  • cyanine dyes derived from nitro substituted 2-arylindoles are outstanding electron acceptors and spectral sensitizers for direct positive type photographic silver halide emulsions. They provide superior reversal systems, especially with fogged silver halide emul sions, that are characterized by both good speed and desired sensitivity to radiation in the green to red region of the spectrum with maximum sensitivity occurring in most cases in the region of about 540-640 mm. I have found further that the inclusion of color-forming couplers in these novel direct positive emulsions results in unexpectedly desirable holding or keeping stability of the emulsion melts.
  • n represents a positive integer of from 1 to 2;
  • R 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, cyclohexyl, decyl, etc., in aryl group, e.g., phenyl, tolyl, naphthyl, chlorophenyl, etc., a heterocyclic group such as a thienyl group, and the like, at least one R representing hydrogen;
  • R and R each represents an alkyl group, including substituted alkyl, (preferably a lower alkyl containing from 1 to 4 carbon atoms), e.g., methyl, ethyl, propyl, isopropyl, butyl, hexyl, cyclohexyl, decyl, dodecyl, etc., and substitute
  • desensitizing nucleus refers to those nuclei which, when converted to a symmetrical carbocyanine dye and added to gelatin silver chlorobromide emulsion containing 40 mole percent chloride and 60 mole percent bromide, at a concentration of from 0.01 to 0.2 gram dye per mole of silver, cause by electron trapping at least about an percent loss in the blue speed of the emulsion when sensitometrically exposed and developed three minutes in Kodak developer D-19 at room temperature.
  • the densensitizing nuclei are those which, when converted to a symmetrical carbocyanine dye and tested as just described essentially completely densenitize the test emulsion to blue radiation (i.e., cause more than about to loss of speed to blue radiation).
  • symmetrical cyanine dyes defined by Formula I above wherein R is a S-nitro group are conveniently prepared by reacting a mixture comprising (1) an indole of the formula:
  • R and R are as previously defined, with (2) a compound such as 1,3,3-trimethoxypropene, in the presence of (3) a strong acid HX such as a mineral acid or an organic sulfonic acid, e.g., hydrobromic, perchloric, p-toluenesulfonic, etc. acids, in an inert solvent medium such as hot glacial acetic acid, in the proportions of about 2 moles of (1) and at least 1 mole of each of (2) and (3).
  • a strong acid HX such as a mineral acid or an organic sulfonic acid, e.g., hydrobromic, perchloric, p-toluenesulfonic, etc. acids
  • an inert solvent medium such as hot glacial acetic acid
  • R, R, R and R are as previously defined, except that R, in this case does not include the S-nitro group, with an indole of Formula V in the presence of a strong acid and in the absence of trimethoxypropene.
  • 21 similar procedure can be used to prepare related chain-substituted dyes by reacting a compound similar to Formula V, but which is not nitro substituted,
  • R X and Z are previously defined, in approximately equimolar proportions of (1) and (2), in an inert solvent medium such as hot acetic anhydride.
  • the crude dye obtained is purified by one or more recrystallizations from appropriate solvents such as methanol.
  • R and R are as previously defined, by reaction with sodium nitrate, in approximately equimolar proportions, in a concentrated sulfuric acid medium, at temperatures not exceeding acid, the solution is chilled, and the sodium nitrate dissolved in sulfuric acid added dropwise with stirring, and ice-bath cooling.
  • the nitrated indole obtained is purified by one or more recrystallizations from an appropriate solvent such as dimethylformamide.
  • the emulsion may be fogged by the addition thereto of a reducing agent, such as thiourea dioxide, and a compound of a metal more electropositive than silver, such as a gold salt, for example, potassium chloroaurate, as described in British Pat. 723,019 (1955).
  • a reducing agent such as thiourea dioxide
  • a compound of a metal more electropositive than silver such as a gold salt, for example, potassium chloroaurate, as described in British Pat. 723,019 (1955).
  • the concentration of added dye can vary widely, e.g., from about 50 to 2000 mg. and preferably from about 400 to 800 mg. per mole of silver halide in the direct positive emulsions.
  • fogged refers to emulsions containing silver halide grains which produce a density of a least 0.5 when developed, without exposure, for 5 minutes at 68 F. in developer Kodak DK-SO having the composition set forth below, when the emulsion is coated at a silver coverage of 50 mg. to 500 mg. per square foot.
  • Fogging by means of a reduction sensitizer, a noble metal salt such as gold salt plus a reduction sensitizer, a sulfur sensitizer, high pH and low pAg silver halide precipitating conditions, and the like can be suitably utilized.
  • the shell portion of the subject grains can also be coated prior to fogging.
  • the core emulsion is first chemically or physically treated by methods previously described in the prior art to produce centers which promote the deposition of photolytic silver, i.e., latent image nucleating centers.
  • centers can be obtained by various techniques as described herein. Chemical sensitization techniques of the type described by Antoine Hautot and Henri Sauvenier in Science et Industries Photographiques, vol. XXVIII, January 1957, pages 1 to 23 and January 1957, pages 57 to 65 are particularly useful.
  • Such chemical sensitization includes three major classes, namely, gold or noble metal sensitization, sulfur sensitization, such as by a labile sulfur compound, and reduction sensitization, e.g., treatment of the silver halide with a strong reducing agent which introduces small specks of metallic silver into the silver salt crystal or grain.
  • the dyes of this invention are highly useful electron acceptors in high speed direct positive emulsions comprising fogged silver halide grains and a compound which accepts electrons, as described and claimed in Illingsworth U.S. patent application Ser. No. 619,936, filed Mar. 2, 1967, and titled Photographic Reversal Materials Case C.
  • the fogged silver halide grains of such emulsions are such that a test portion thereof, when coated as a photo graphic silver halide emulsions on a support to give a maximum density if at least about one upon processing for six minutes at about 68 F.
  • Kodak DK-SO developer in Kodak DK-SO developer, has a maximum density which is at least about 30% greater than the maximum density of an identical coated test portion which is processed for six minutes at about 68 F. in Kodak DK-SO developer after being bleached for about 10 minutes at about 68 F. in a bleach composition of:
  • the grains of such emulsions will lose at least about 25% and generally at least about 40% of their fog when bleached for ten minutes at 68 F. in a potassium cyanide bleach composition as described herein.
  • This fog loss can be illustrated by coating the silver halide grains as a photographic silver halide emulsion on a support to give a maximum density of at least 1.0 upon processing for six minutes at about 68 F. in Kodak DK-50 developer and comparing the density of such a coating with an identical coating which is processed for six minutes at 68 F. in Kodak DK-SO developer after being bleached for about 10 minutes at 68 F. in the potassium cyanide bleach composition.
  • the maximum density of the unbleached coating will be at least 30% greater, generally at least 60% greater, than the maximum density of the bleached coating.
  • the silver halides employed in the preparation of the photographic emulsions useful herein include any of the photographic silver halides as exemplified by silver bromide, silver iodide, silver chloride, silver chlorobromide, silver bromoiodide, silver chlorobromide, and the like.
  • the silver halide grains can be regular and can be any suitable shape such as cubic or octahedral, as described and claimed in Illingsworth U.S. patent application Ser. No. 619,009, filed Mar. 2, 1967, and titled Direct Positive Photographic Emulsions Case A, now U.S. Pat. No.
  • Such grains advantageously have a rather uniform diameter frequency distribution, as described and claimed in Illingsworth U.S. patent aplication Ser. No. 619,948, filed Mar. 2, 1967, and titled Photographic Reversal Emulsions Case B, now U.S. Pat. No. 3,501,305.
  • at least by weight, of the photographic silver halide grains can have a diameter which is Within about 40%, preferably within about 30% of the mean grain diameter.
  • Mean grain diameter i.e., average grain size, can be determined using conventional methods, e.g., as shown in an article by Trivelli and Smith entitled Empirical Relations Between Sensitometric and Size-Frequency Characteristics in Photographic Emulsion Series in The Photographic Journal, vol.
  • 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 kIlOIWH 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 completely 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 new dyes 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, agar-agar, 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.
  • dispersed polymerized vinyl compounds are disclosed, for example, in U.S. 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 dyes, reducing agents and metal compounds of the invention can be used with emulsions prepared, as indicated above, with any of the light-sensitive silver halide salts including silver chloride, silver bromide, silver chlorobromide, silver bromoiodide, silver chlorobromoiodide, etc.
  • Particularly useful are direct positive fogged emulsions in which the silve salt is a silver bromohalide comprising more than 50 mole percent bromide.
  • Certain dyes of this invention are also useful in emulsions which contain color formers.
  • the above prepared dye containing two desensitizing 1-methyl-5-nitro-2-phenylindole nuclei is photographically tested for its usefulness as an electron acceptor and spectral sensitizer for fogged direct positive photographic silver halide emulsions by the following procedure.
  • a sample of the coated support is then exposed on an Eastman Ib sensitometer using a tungsten light source and processed for 6 minutes at room temperature in Kodak D-19 developer which has the following composition:
  • the dye of this example has a maximum density in the unexposed areas of 1.74 and a minimum density in exposed areas of 0.22, a maximum sensitivity at 630 nm. and a relative speed of 725, whereas the control sample similarly prepared and tested but containing no spectral sensitizing dye shows no reversal and has a relative speed less than 1.
  • the dye compound of the above example is especially well suited to function as a spectral sensitizer. It thus provides excellent quality direct positive photographic silver halide emulsions.
  • This dye containing the desensitizing 1-methyl-5-nitro- Z-phenylindole and 3-ethyl-6-nitrobenzothiazole nuclei is tested for reversal and sensitizing properties by the procedure described in above Example 1.
  • the results are recorded in Table l hereinafter. Referring to the table, densities of 1.78 and 0.03 for the unexposed and exposed areas, respectively, a maximum sensitivity at 550 nm. and a relative speed of 1100 are shown for this dye. Accordingly, the above prepared dye is an excellent electron acceptor and spectral sensitizer for fogged direct positive emulsions.
  • cyanine dyes of the invention defined by Formulas I and II can be prepared having generally similar properties as electron acceptors and spectral sensitizers, together with improved hold properties, in direct positive photographic emulsions which may also contain colorforming couplers and colored couplers.
  • Typical dyes include the 1,1 dimethyl 5,5 dinitro 2,2 diphenyl- 3,3-indolocarbocyanine salts (e.g., the chloride, bromide, iodide, perchlorate, sulfamate, p-toluenesulfonate, etc.
  • 1,1 dibutyl 5,5 dinitro 2,2 diphenyl 3,3- indolocarbocyanine salts e.g., the chloride, bromide, iodide, perchlorate, sulfamate, p-toluenesultonate, etc.
  • the 3 ethyl 1 methyl- 5,6 dinitro 2 phenyl 3 indoloselenacarbocyanine salts e.g., the chloride, bromide, iodide, perchlorate, sulfamate, p-toluenesulfonate, etc. salts
  • the 3 ethyl- 1 methyl 5,6 dinitro 2 phenyl 3 indolo oxacarbocyanine salts e.g., the chloride, bromide, iodide, perchlorate, sulfamate, p-toluenesulfonate, etc.
  • EXAMPLE 4 This example compares the speeds of an incorporated coupler emulsion sensitized with the dye of above Example 3 and two other related dyes containing no nitro substituents, half of these melts being coated immediately after formulation and the other half after a 50-minute hold at 40 C.
  • the test procedure is as follows:
  • All dyes of this invention can, however, be advantageously used with any of the photographic color formers, including monomeric and polymeric color formers, such as pyrazolone, phenolic, heterocyclic, and open chain couplers having a reactive methylene group, such as any of those specifically referred to in the Jelley et al., Fierke et al., Fisher and Wilmanns patents identified below, or in U.S. Pat. 2,600,788 or 2,983,608, to provide emulsions which retain this spectral sensitivity during storage.
  • monomeric and polymeric color formers such as pyrazolone, phenolic, heterocyclic, and open chain couplers having a reactive methylene group, such as any of those specifically referred to in the Jelley et al., Fierke et al., Fisher and Wilmanns patents identified below, or in U.S. Pat. 2,600,788 or 2,983,608, to provide emulsions which retain this spectral sensitivity
  • EXAMPLE 5 1-methyl-5-nitro-2-phenylindole l-methyl-Z-phenylindole (10.35 g., 1 mol.) is dissolved in 99% sulfuric acid (50 ml.). The solution is chilled in an ice-bath to 2 C. and a solution of sodium nitrate (4.25 g., 1 mol.) in 99% sulfuric acid (40 ml.) is added dropwise over a period of about 30 minutes, with stirring, and ice-bath cooling. The temperature rises to a maximum of 8 C. The mixture is stirred a further 5 minutes, then poured onto ice (350 g.), with stirring. The solid is collected and washed with Water. After one recrystallization from dimethyl formamide, the yield of purified material is 9.6 g. (76%), M.P. 1824 C.
  • a direct positive, photographic emulsion in accordance with claim 1 which comprises fogged silver halide grains, at least by weight, of said grains having a diameter which is within about 40% of the mean grain diameter.
  • a direct positive photographic emulsion in accordance with claim 10 which comprises fogged silver halide grains, at least by weight, of said grains having a diameter which is within about 40% of the mean grain diameter.
  • a direct positive photographic emulsion in accordance with claim 10 containing a cyanine dye selected from the group consisting of 1,1'-dimethyl-5,5'-dinitro-2,2'-diphenyl-3,3'-indolocarbocyanine salt; 3'-ethyl-l-methyl- 5,6-dinitro-2-phenyl-3-indolothiacarbocyanine salt; and 1,3 diallyl 1 -'methyl-5-nitro-2'-phenylimidazo [4,5-b] quinoxalino-B-indolocarbocyanine salt.
  • a cyanine dye selected from the group consisting of 1,1'-dimethyl-5,5'-dinitro-2,2'-diphenyl-3,3'-indolocarbocyanine salt; 3'-ethyl-l-methyl- 5,6-dinitro-2-phenyl-3-indolothiacarbocyanine salt; and 1,3 dially
  • a photographic element comprising a support having thereon at least one layer containing a direct positive emulsion of claim 9.
  • a photographic element comprising a support having thereon at least one layer containing a direct positive emulsion of claim 10.
  • a photographic element comprising a support having thereon at least one layer containing a direct positive emulsion of claim 16.

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US754965A 1968-08-23 1968-08-23 Direct positive silver halide emulsions containing a 5 nitro -2- arylindole nucleus Expired - Lifetime US3582343A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030932A (en) * 1975-05-28 1977-06-21 Eastman Kodak Company Silver halide sensitized with dyes containing an isoindole nucleus

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IT988269B (it) * 1973-06-18 1975-04-10 Minnesota Mining & Mfg Coloranti cianinici e loro impiego come sensibilizzatori spettrali in materiali fotografici positivi diretti del tipo ad effetto herschel sensibilizzato spettralmente

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030932A (en) * 1975-05-28 1977-06-21 Eastman Kodak Company Silver halide sensitized with dyes containing an isoindole nucleus

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