Parton, Richard L. c/o Eastman Kodak Compan; Gingello, Anthony D. c/o Eastman Kodak Compan; Collett, David J. c/o Eastman Kodak Company; Stegman, David Alan c/o Eastman Kodak Compan, Rochester New York 14650, US
The present invention relates to infrared absorbing dyes and photographic
elements comprising a layer containing such dyes.
Photographic elements having layers comprising filter dyes are known.
These filter dyes may be used for a variety of purposes, such as absorber dyes
in photographic emulsion layers to improve the image sharpness of that layer, general
purpose filter dyes for absorbing light of a particular wavelength so it does
not expose or exposes at a reduced intensity a lower layer in the element, or
as antihalation dyes to reduce halation in the image-forming layers.
Filter dyes may be present in essentially any layer of a photographic
element where it is desired to absorb radiation in the region of the spectrum
where the dye absorbs light, such as an interlayer, a radiation sensitive layer,
an overcoat layer, an undercoat layer, a backing layer, or others known in the
art. Absorber dyes (also called intergrain absorber dyes) are generally present
in the radiation sensitive layers of photographic elements. Antihalation layers
may be located on either side of a transparent support carrying radiation sensitive
layers, particularly silver halide emulsion layers. Moreover, such antihalation
layers may be coated between two or more silver halide emulsions layers in a multilayer
element or as a backing layer on the side of the support away from the light sensitive
The development of information recording equipment using semiconductor
laser diodes emitting in the infrared spectral region has required a parallel
development of photographic elements, particularly silver halide photographic elements,
with appropriate spectral sensitivity. Such elements often require the presence
of filter dyes that absorb infrared radiation in one or more layers of the element,
for example, as antihalation dyes or absorber dyes.
Such filter dyes should:
(1) filter light in the region from 730 nm to 900 nm, depending on the emission
wavelength of the laser diode (a common laser emission wavelength is in the range
of 800 nm amd other typical laser emission wavelengths are in the ranges of 750,
780, 820, and 870 nm),
(2) be water soluble at levels of at least 5 mg/ml so as to allow aqueous dissolution
of the dye and provide compatibility with hydrophilic layers, and
(3) leave little or no stain in the processed film. U.S. Patent 4,362,800 discloses
salt. This dye has been used with some success as a photographic filter dye, but
it tends to leave a greenish stain after processing. Such a stain is objectionable.
GB 2 089 055 A discloses 1,1,1',1'-tetramethyl-3,3'-bis(carboxymethyl)-1H-indolotricarbocyanine
as compound n. 76 for use as a filter dye in an electrophotographic film. Post-processing
stain is not a factor in an electrophotographic film, but if this dye were to
be used in a photographic material subject to processing, it would leave objectionable
stain. Other dyes, such as those disclosed in U.S. Application serial no. 881,312,
entitled Novel Infrared Absorbing Dyes and Photographic Elements Containing Same,
filed July 2, 1986, require the use of a deaggregant to obtain the proper absorption
wavelength. Deaggregants, however, can cause adverse photographic effects, such
as speed loss. Thus, a nonstaining infrared filter dye is needed.
The present invention provides infrared-absorbing filter dyes having
In this formula, R&sub1; and R&sub2; each independently represents
substituted or unsubstituted: sulfoalkyl, carboxyalkyl, or sulfatoalkyl, from
2 to 4 carbon atoms, having 2 carbon atoms in the alkyl chain linking the nitrogen
atom of each Z ring and the sulfo or sulfato group, and 1 carbon atom in the alkyl
chain linking the nitrogen atom of each Z ring and the carboxy group.
R&sub3; and R&sub5; are each hydrogen or together represent the atoms
necessary to complete a substituted or unsubstituted 5- or 6-membered carbocyclic
ring, and R&sub4; represents hydrogen, substituted or unsubstituted alkyl of 1
to 4 carbon atoms, substituted or unsubstituted aryl, halogen, cyano, or
where R&sub6; and R&sub7; each independently represents substituted
or unsubstituted alkyl of from 1 to 6 carbon atoms or substituted or unsubstituted
aryl or together represent the non metallic atoms necessary to form a substituted
or unsubstituted 5- or 6-membered heterocyclic ring.
X⊕ represents a cation.
Z&sub1; and Z&sub2;, each independently represent the atoms
needed to complete a substituted or unsubstituted: indole, naphthindole or benzindole
Such dyes can be used effectively as filter dyes in infrared-sensitive
photographic elements without requiring a deaggregant and without leaving an objectionable
With dyes according to formula (I), R&sub1; and R&sub2; each independently
represent sulfoalkyl, carboxyalkyl, or sulfatoalkyl of from 2 to 4 carbon atoms,
having 2 carbon atoms in the alkyl chain linking the nitrogen atom of each Z ring
and the sulfo or sulfato group, and 1 carbon atom in the alkyl chain linking the
nitrogen atom of each Z ring and the carboxy group. Additionally, substituted
sulfoalkyl, carboxyalkyl, and sulfatoalkyl are useful as R&sub1; and R&sub2;. Such
groups may be substituted with substituents such as hydroxy and halogen such as
Cl or F. Examples of R&sub1; and R&sub2; include sulfoethyl, carboxymethyl, and
R&sub3; and R&sub5; each independently represent hydrogen or together
represent the atoms necessary to complete a 5- or 6-membered carbocyclic ring,
such as cyclopentenyl or cyclohexenyl. Substituted carbocyclic rings (substituted
with, for example, alkyl such as methyl, ethyl, propyl, and butyl, halogen, or
hydroxy) are also useful as R&sub3; and R&sub5; (e.g., 5-hydroxycyclohexenyl or
R&sub4; represents hydrogen, alkyl of from 1 to 4 carbon atoms such
as methyl, ethyl, or propyl,
halogen such as F, Cl, etc., cyano, or Substituted alkyl (substituted
with, for example, hydroxy, halogen such as Cl or F, or aryl such as phenyl) are
also useful as R&sub4; (e.g., hydroxymethyl, phenoxymethyl, or phenylmethyl). R&sub6;
and R&sub7; each individually represent alkyl of from 1 to 6 carbon atoms (e.g.,
methyl, ethyl, propyl), aryl (e.g., phenyl, p-methoxyphenyl), or together represent
the non-metallic atoms necessary to complete a 5- or 6-membered heterocyclic ring.
Examples of such heterocyclic ring groups include morpholino, thiomorpholino,
and piperazino, such as 4-ethoxycarbonyl-1-piperazino and 4-methyl-1-piperazino.
Additionally, substituted alkyl, aryl, or heterocyclic rings are useful as R&sub6;
and R&sub7;. Useful substituents include hydroxy, alkoxy, halogen, acetyl, carboxy,
or sulfo, and useful substituted groups include hydroxyethyl, 4-chlorophenyl,
4-methoxyphenyl, 4-sulfophenyl, and 2-carboxyethyl.
It is contemplated herein that indole, naphthindole, or benzindole
nuclei that are substituted with substituents such as halogen (e.g., Cl or F),
sulfo, carboxy, hydroxy, alkyl (e.g., methyl), hydroxyalkyl such as hydroxymethyl,
carboxyalkyl such as carboxymethyl, or aryl (e.g., phenyl or p-sulfophenyl) are
also useful as Z&sub1; and Z&sub2; according to the present invention.
A preferred class of dye compounds according to formula (I) are represented
where X⊕, R1, R2, R3, R4, and R5, are as defined above,
R&sub8;, R&sub9;, R&sub1;&sub0; and R&sub1;&sub1; each independently
represent methyl or ethyl, or R&sub8; and R&sub9; or R&sub1;&sub0; and R&sub1;&sub1;,
taken together with the carbon atoms to which they are attached, may form a cycloalkyl
group. Also useful as R&sub8;, R&sub9;, R&sub1;&sub0;, and R&sub1;&sub1; include
groups substituted with substituents such as hydroxy, sulfato, and carboxy. Examples
of useful substituted groups include hydroxymethyl, sulfatomethyl, and carboxyethyl.
The dyes of formula (I) can be made according to the procedures of
U.S. Patents 2,895,955, 3,148,187, and 3,423,207. Such a preparation procedure
is illustrated in Example 1 infra.
A deaggregant is not needed or even necessarily desirable for the
dyes of formula (I). The dyes of formula (I) have an absorbance maximum in the
desired wavelength range in molecular form and do not aggregate. These dyes avoid
the necessity of using a deaggregant, which can cause adverse photographic effects
such as speed loss during storage.
Examples of dyes useful in the invention include:
The dyes of formula (I) can be incorporated in a photographic element
in any amount known to be effective as a filter dye in photographic elements.
In a preferred embodiment, the dyes useful in the invention are in a hydrophilic
colloid layer of a photographic element at a concentration of from 9.3 ×
10&supmin;&sup4; to 4.7 g/m². The deaggregant is preferably present in an amount
of from 25 to 10,000 weight percent, based on the weight of the dye.
When used as an antihalation dye, the dye of formula (I) is preferably
present in a layer at a level of from 9.3 × 10&supmin;³ to 4.7 g/m²
and more preferably from 0.047 to 0.93 g/m². Antihalation layers are prepared
by coating on the photographic element or on its support, by methods well-known
in the art, a water solution of the dye, the deaggregant, a hydrophilic colloid
binder and a coating aid such as saponin.
When used as an absorber dye in a photo sensitive layer of a photographic
element, the dye of formula (I) is preferably present at a level of from 9.3 ×
10&supmin;&sup4; to 0.47 g/m² and more preferably from 2.8 ×10&supmin;³
to 0.19 g/m². The dye causes little speed loss does not adversely affect storage
stability. Such layers are prepared by coating on the photographic element or
on its support, by methods well-known in the art, an emulsion of silver halide
grains, a hydrophilic colloid binder, and the dye, as well as other addenda known
to be included in photosensitive layers, such as sensitizing dyes (e.g., infrared
sensitizing dyes), dye-forming image couplers, and the like.
For many purposes, it is desirable to add agents to harden the colloidal
binder material so that the filter dye-containing layer remains intact in the
photographic element during and following the processing operation. The pH of the
coating solution is adjusted when necessary by the usual methods to a level that
is compatible with the light-sensitive emulsion layer.
The proportions of dye, deaggregant, water-permeable hydrophilic
colloid binder, hardener, silver halide (if present), sensitizing dye (if present),
and coating aid used in making layers containing the filter dye of formula (I)
may be varied over wide ranges and will depend upon the specific requirements
of the photographic element being produced. The method used to determine the optimum
composition is well known in the art and need not be described here.
The photographic elements may be coated on any suitable support material
used in photography such as polyethylene terephthalate,cellulose nitrate, cellulose
acetate, papers, etc.
Hydrophilic colloidal materials used as binders include gelatin,
gelatin substitutes, collodion, gum arabic, cellulose ester derivatives such as
alkyl esters of carboxylated cellulose, hydroxy ethyl cellulose, carboxy methyl
hydroxy ethyl cellulose, synthetic resins, such as the amphoteric copolymers described
by Clavier et al, in U.S. Patent 2,949,442, issued August 16, 1960, polyvinyl alcohol,
and others well known in the art.
Examples of polymeric gelatin substitutes are copolymers of allylamine
and methacrylic acid, copolymers of allylamine, acrylic acid and acryl-amide,
hydrolyzed copolymers of allylamine, methacrylic acid and vinyl acetate, the copolymers
of allylamine, acrylic acid and styrene, the copolymers of allylamine, methacrylic
acid and acrylonitrile, etc.
The dye and the deaggregant are generally added to the water permeable
colloidal binder in water or methanol solution. Usually a coating aid, such as
saponin, is added to the dyed colloidal suspension before coating it as a layer
on the photographic element.
The photographic elements utilizing the filter dyes of formula (I)
have infrared light-sensitive emulsion layers. Such layers may contain silver
chloride, silver bromide, silver chlorobromide, silver iodide, silver bromoiodide,
silver chlorobromoiodide, etc., as the light-sensitive material. Indeed, any infrared
absorbing light-sensitive silver halide emulsion layer may be used in these photographic
elements. The silver halide emulsion are sensitized for infrared absorption by
any of the sensitizers commonly used to produce the desired sensitometric characteristics.
Methods of making such elements, the means for sensitizing them to
infrared radiation and the incorporation of filter dyes in silver halide emulsion
layers or antihalation layers are well known and need not be described herein.
Detailed teachings in this regard can be obtained from Research Disclosure, 1978,
Item 17643 entitled "Photographic Silver Halide Emulsions, Preparations, Addenda,
Processing and Systems."
The practice of the invention is further illustrated by the following
examples. The structures of the dyes of the Examples are given in the Tables I,
II, and III.
Example 1: Preparation of Dye 1 Step 1 - Preparation of 7-sulfo-1,1,2-trimethyl-1H-benz[e]indole sodium
salt (Intermediate A)
1,1,2-Trimethyl-1H-benz[e]indole (100 g) was added with stirring
to 500 ml of concentrated H&sub2;SO&sub4;. The mixture was heated at 180 °C for
1/2 hour, cooled to 6-°C, and poured onto 2 kg ice. 500 ml of 50% aqueous NaOH
was added slowly. After 24 hours at room temperature, the solid precipitate that
had formed was filtered off and the filtrate was mixed with 500 ml saturated aqueous
Na&sub2;SO&sub4;. The resulting precipitate was collected, added to the previously
filtered solid precipitate, and recrystallized from 2 l of H&sub2;O. This recrystallized
material (25 g) was dried overnight under vacuum at 50°C. Purity was determined
by nuclear magnetic resonance. This material was converted to the sodium salt
by dissolving it in water, adding 1 equivalent of sodium bicarbonate, and evaporating
Step 2 - Preparation of anhydro-7-sulfo-3-(2-sulfoethyl)-1,1,2-trimethyl-1H-benz[e]indolinium
hydroxide sodium salt (Intermediate B)
A mixture of 9.3 g intermediate A and 5.3 g 2-chloroethanesulfonyl
chloride in 100 ml of acetic acid were refluxed for 2 hours. After cooling to
room temperature, the solvent was removed under vacuum and 100 ml of ethanol was
added. The solid was collected and dried to yield a compound that was confirmed
to be intermediate B by NMR spectrum.
Step 4 - Preparation of anhydro-3,3&min;-di-(2-sulfoethyl)-7,7&min;-disulfo-1,1,1&min;,1&min;-tetramethylbenz[e]indolotricarbocyanine
hydroxide trisodium salt (dye 1 of Table I)
2.0 g of intermediate B and 0.6 g glutacondialdehyde dianil hydrochloride
were combined in 15 ml of acetic anhydride with 3 ml of triethylamine. The mixture
was heated at reflux for 4 minutes. The solid formed was collected and washed with
acetic anhydride, and then dissolved in a 50/50 mixture of methanol and water
with heating. The solution was filtered and excess sodium acetate was added to
the filtrate. After cooling, the solid was filtered out of the solution, washed
with methanol, and dried. This material was dye 1 of Table I, λ-max = 784
nm in methanol, ε-max = 22.34 × 10&sup4;.
Example 2 - Preparation of anhydro-13-(4-ethoxycarbonyl-l-piperazinyl)-12,14-ethylene-3,3&min;-di-(2-sulfoethyl)-7,7&min;-disulfo-1,1,1&min;,1&min;-tetramethylbenz[e]indolotricarbocyanine
hydroxide trisodium salt (dye 2 of Table II)
2.1 g of intermediate B from Example 1 and 1.3 g 1-[2,5-bis(anilinomethylene)cyclopentylidene]-4-ethoxycarbonylpiperazinium
tetrafluoroborate were combined in 10 ml N-methylpyrrolidinone and 4 ml triethylamine
and heated at 200°C for 15 minutes. After cooling to room temperature ether was
added with stirring. The ether phase was then decanted and the product was dissolved
in methanol and heated to reflux. Excess sodium acetate was added and the mixture
was cooled to room temperature. The solid was collected and recrystallized from
a 50/50 mixture of methanol and water to yield dye 2 of Table II, λ-max
= 726 nm in methanol, ε-max = 13.01 × 10&sup4;.
This example illustrates the desirable absorption but severe post
processing stain problem of comparison dyes having structures similar to the dyes
useful in the invention (comparison dyes 6-9), the undesirable absorption of dyes
5 and 10, and the desired absorption and low residual stain of dyes 1-4 used according
to the invention.
Coating compositions of this example were prepared by adding the
components, at predetermined levels based on the coverages desired in coated layers
of the composition, to a hydrophilic material such as gelatin. In these examples
the compositions were coated on a polyethylene terephthalate support to achieve
gelatin coverage of 3.14 g/m² and component coverage as listed in Table IV. Absorption
spectra were obtained using a Diano Match Scan II Spectrophotometer before and
Processing was by the rack and tank method with development for 30
s at 38°C in Kodak Rapid Scanner Developer, fixing at 38°C. in Kodak Rapid Fixer
and washing for 60 s at about 32°C. Total transmittance density measurements were
made before and after processing to indicate stain levels before and after processing.
A visual evaluation was also made of the post process stain. The results are listed
in Table IV. In correlating the visual evaluation of stain with observed spectral
curves it should be noted that the eye is sensitive to near 750 nm.
Comparison Dyes 6-9 show strong absorption in the spectral region
of interest. However, they also show severe post-processing stain. Comparison
dyes 5 and 10 show some absorption in the 800 nm range, but they have an aggregate
peak beyond 900 nm, rendering them unsuitable as infrared absorbing antihalation
In Table IV, coatings 7-10 contain dye compositions useful in the
invention. Coatings 1, 2, 3, 4, 5, and 6 contain dyes 5, 6, 7, 8, 9, and 10, respectively,
identified in Tables I-III as comparison dyes.
In Table IV, the stain evaluation, done visually, is recorded using
the code VS = very severe, S = severe, M = moderate, SL = slight and BD = barely
detectable. Other symbols include * which indicates that the dye in this coating
had an aggregate peak beyond 900 nm. The optical density (OD) of the aggregate
peak is much higher than the maximum in the table. λ-max is the peak with
the highest OD in the 300 to 900 nm region λ-sec indicates a secondary
maximum or, in most cases, a shoulder (labeled s) or slight curve inflection (labeled
Photographisches Element mit einem Träger, auf dem sich eine hydrophile Kolloidschicht
befindet, mit infrarotempfindlichem Silberhalogenid und einem Infrarot-Filterfarbstoff
entweder in der Silberhalogenidschicht oder einer anderen hydrophilen Kolloidschicht,
dadurch gekennzeichnet, daß der Farbstoff der folgenden Formel entspricht:
in der bedeuten: R&sub1; und R&sub2; unabhängig voneinander substituiertes oder
unsubstituiertes Sulfoalkyl, Carboxylalkyl oder Sulfatoalkyl, das 2 bis 4 Kohlenstoffatome
enthält, mit 2 Kohlenstoffatomen in der Alkylkette, die das Stickstoffatom jedes
Z-Ringes und die Sulfo- oder Sulfatogruppe verbindet und einem Kohlenstoffatom
in der Alkylkette, die das Stickstoffatom jedes Z-Ringes und die Carboxygruppe
R&sub3; und R&sub5; jeweils Wasserstoff oder gemeinsam die Atome, die zur Vervollständigung
eines substituierten oder unsubstituierten 5- oder 6-gliedrigen carbocyclischen
Ringes erforderlich sind,
R&sub4; Wasserstoff, substituiertes oder unsubstituiertes Alkyl mit 1 bis 4 Kohlenstoffatomen,
substituiertes oder unsubstituiertes Aryl, Cyano, Halogen oder
worin R&sub6; und R&sub7; jeweils unabhängig voneinander darstellen: substituiertes
oder unsubstituiertes Alkyl mit 1 bis 6 Kohlenstoffatomen oder substituiertes oder
unsubstituiertes Aryl oder gemeinsam die nicht-metallischen Atome, die zur Vervollständigung
eines substituierten oder unsubstituierten 5- oder 6-gliedrigen heterocyclischen
Ringes erforderlich sind,
X⊕ ein Kation und
Z&sub1; und Z&sub2; jeweils unabhängig voneinander die Atome, die zur Vervollständigung
eines substituierten oder unsubstituierten Indol-, Naphthindol- oder Benzindolkernes
Photographisches Element nach Anspruch 1, in dem der Farbstoff in einer Menge
von 9,3 x 10&supmin;&sup4; bis 4,7 g/m² vorliegt.
Photographisches Element nach Ansprüchen 1 oder 2, in dem die Schicht mit dem
Farbstoff frei von einer deaggregierenden Verbindung ist.
Photographisches Element nach Ansprüchen 1-3, in dem der Farbstoff der folgenden
in der X⊕ R&sub1;, R&sub2;, R&sub3;, R&sub4; und R&sub5; die in Anspruch 1
angegebene Bedeutung haben,
R&sub8;, R&sub9;, R&sub1;&sub0; und R&sub1;&sub1; jeweils unabhängig voneinander
Methyl oder Ethyl bedeuten oder
R&sub8; und R&sub9; oder R&sub1;&sub0; und R&sub1;&sub1; gemeinsam mit den Kohlenstoffatomen,
an die sie gebunden sind, eine Cycloalkylgruppe darstellen.
Photographisches Element nach Ansprüchen 1-4, in dem der Farbstoff in der Silberhalogenidschicht
Photographisches Element nach Ansprüchen 1-4, in dem der Farbstoff ein Lichthofschutzfarbstoff
ist, der in einer anderen als der Silberhalogenidschicht vorliegt.
A photographic element comprising a support having thereon a hydrophilic colloid
layer comprising infrared-sensitive silver halide and an infrared filter dye,
either in the silver halide layer or another hydrophilic colloid layer, characterized
in that the dye has the formula:
R&sub1; and R&sub2; each independently represents substituted
or unsubstituted: sulfoalkyl, carboxyalkyl, or sulfatoalkyl containing from 2 to
4 carbon atoms, having 2 carbon atoms in the alkyl chain linking the nitrogen
atom of each Z ring and the sulfo or sulfato group, and 1 carbon atom in the alkyl
chain linking the nitrogen atom of each Z ring and the carboxy group,
R&sub3; and R&sub5; are each hydrogen or together represent
the atoms necessary to complete a substituted or unsubstituted 5- or 6-membered
R&sub4; represents hydrogen, substituted or unsubstituted
alkyl of 1 to 4 carbon atoms, substituted or unsubstituted aryl, cyano, halogen
where R&sub6; and R&sub7; each independently represent substituted or unsubstituted
alkyl of from 1 to 6 carbon atoms or substituted or unsubstituted aryl or together
the non-metallic atoms necessary to form a substituted or unsubstituted 5- or 6-membered
x+ represents a cation, and
Z&sub1; and Z&sub2;, each independently represent the atoms
needed to complete a substituted or unsubstituted: indole, naphthindole or benzindole
A photographic element according to Claim 1 wherein the dye is present in an
amount of from 9.3 x 10&supmin;&sup4; to 4.7 g/m².
A photographic element according to Claims 1 or 2 wherein the layer comprising
the dye is free from any deaggregating compound.
A photographic element according to Claims 1-3 wherein the dye has the structure:
wherein X⊕, R&sub1;, R&sub2;, R&sub3;, R&sub4;, and R&sub5;, are
as defined in Claim 1,
R&sub8;, R&sub9;, R&sub1;&sub0;, and R&sub1;&sub1; each independently
represent methyl or ethyl, or
R&sub8; and R&sub9;, or R&sub1;&sub0; and R&sub1;&sub1;, taken
together with the carbon atoms to which they are attached, may form a cycloalkyl
A photographic element according to Claims 1-4 wherein the dye is in the silver
A photographic element according to Claims 1-4 wherein the dye is an antihalation
dye present in a layer other than the silver halide layer.
Produit photographique comprenant un support portant une couche de colloïde
hydrophile comprenant des halogénures d'argent sensibles à l'infra-rouge et un
colorant filtrant l'infrarouge, soit dans la couche d'halogénure d'argent soit
dans une autre couche de colloïde hydrophile, caractérisé en ce que le colorant
correspond à la formule :
R&sub1; et R&sub2;, représentent chacun séparément des groupes substitués ou non
sulfoalkyles, carboxyalkyles, ou sulfatoalkyles contenant de 2 à 4 atomes de carbone,
ayant 2 atomes de carbone dans la chaîne alkyle liant l'atome d'azote de chaque
cycle Z et le groupe sulfo ou sulfato, et 1 atome de carbone dans la chaîne alkyle
liant l'atome d'azote de chaque cycle Z et le groupe carboxy,
R&sub3; et R&sub5; sont chacun séparément des atomes d'hydrogène ou, représentent
ensemble les atomes nécessaires pour former un composé carbocyclique à 5 à 6 membres
substitué ou non,
R&sub4; représente un atome d'hydrogène, un groupe alkyle substitué ou non comprenant
1 à 4 atomes de carbone, un groupe aryle, cyano, un halogène ou
où R&sub6; et R&sub7; représentent, chacun séparément un groupe alkyle substitué
ou non comprenant 1 à 6 atomes de carbone ou un groupe aryle substitué ou non,
ou représentent ensemble les atomes non-métalliques nécéssaires pour former un
cycle hétérocyclique, substitué ou non à 5 ou 6 chainons,
x+ représente un cation, et
Z&sub1; et Z&sub2;, chacun séparément, représentent les atomes
nécéssaires pour former des noyaux indole, naphtindole ou benzindole substitués
Produit photographique selon la revendication 1, dans lequel la quantité de
colorant est comprise entre 9,3 x 10-4 et 4,7 g/m².
Produit photographique selon les revendications 1 ou 2 dans lequel la couche
comprenant le colorant ne contient pas de composé provoquant la désagrégation.
Produit photographique selon les revendications 1 à 3 dans lequel la stucture
du colorant est
où X+, R&sub1;, R&sub2;, R&sub3;, R&sub4;, et R&sub5;
sont tels que définis dans la revendication 1,
R&sub8;, R&sub9;, R&sub1;&sub0;, et R&sub1;&sub1;, chacun séparément,
représentent un groupe méthyle ou éthyle, ou
R&sub8; et R&sub9;, ou R&sub1;&sub0; et R&sub1;&sub1;, pris
ensemble avec les atomes de carbone avec lesquels ils sont liés, peuvent former
un groupe cycloalkyle.
Produit photographique selon les revendications 1 à 4, dans lequel le colorant
est dans la couche aux halogénures d'argent.
Produit photographique selon les revendicatione 1 à 4, dans lequel le colorant
est un colorant anti-halo présent dans une couche autre que la couche aux halogénures