Photographic recording material employing a nondiffusible yellow dye-releasing compound

This invention relates to a photographic recording material employing a novel nondiffusible, premetallized, yellow, redox dye-releasing (RDR) compound which, as a function of development of a silver halide emulsion layer, releases a diffusible yellow dye, or precursor thereof, to form a metal-complexed dye image in an image-receiving layer.

U.S. Patent 4,148,643 discloses nondiffusible compounds having a releasable arylazoenol dye moiety. However, the concept of premetallization of such compounds is not suggested in this patent. Moreover, there is also no disclosure in this patent that a fused heterocyclic ring system attached to the azo linkage would provide a more stable 2:1 dye:metal complex than a hydroxy chelating group ortho to the azo linkage, as will be shown hereinafter by the comparative tests.

The object of this invention is to provide improved metal-complexed, yellow dye-releasing compounds so that dyes which are released imagewise during processing can diffuse to an image-receiving layer to form metal-complexed, dye transfer images having better hue, minimum unwanted absorption outside the blue region of the spectrum, narrower bandwidth, rapid diffusion rate and shorter access time than those of the prior art, as well as good stability to heat, light and chemical reagents.

A premetallized RDR, in comparison to a metallizable RDR, provides the further advantage of not having to provide a metal in the mordant layer of the photographic recording material. Free metal ions sometimes tend to diffuse throughout the recording material and to cause sensitometric problems.

A photographic recording material in accordance with this invention comprises at least one photosensitive silver halide emulsion layer having associated therewith a nondiffusible dye image-providing compound having at least one releasable yellow dye moiety, or precursor thereof, characterized in that said compound has the structural formula:

wherein:

• (a) X represents the atoms necessary to complete a 5- or 6-membered aromatic heterocyclic fused ring which can be unsubstituted or substituted;
• (b) Z represents alkyl, substituted alkyl, aryl or substituted aryl;
• (c) R represents CN or J-L;
• (d) J represents a bivalent

  or

  group;

• (e) L represents alkyl, substituted alkyl, aryl or substituted aryl, or L can be taken together with Z to complete a substituted or unsubstituted carbonyl-containing 5- or 6-membered heterocyclic or carbocyclic ring;
• (f) Z¹ represents the same groups as Z;
• (g) each CAR independently represents a ballasted carrier moiety capable of releasing the diffusible yellow dye moiety or precursor thereof as a function of development of a silver halide emulsion layer under alkaline conditions;
• (h) each n is 0 or 1, with the proviso that at least one n is 1;
• (i) Lig is a monoanionic tridentate ligand; and
• (j) Me is a polyvalent, hexacoordinate metal ion.

Typical 5 or 6 membered heterocyclic or carbocyclic rings which can be formed with both L and Z are pyrazolinone, pyrazolidinedione, chromandione and hydantoin.

In the above formula, Me can be any polyvalent, hexacoordinate metal ion as long as it performs the desired function of forming the dye:metal complex. There can be employed, for example, zinc(II), nickel(II), copper(II), cobalt(II), cobalt(III), platinum(II), palladium(II) or chromium(III) ions. Especially good results have been obtained with nickel(II) ions.

In the above formula, Lig can be any monoanionic tridentate ligand which will coordinate with the dye:metal complex. There can be employed, for example, o-(2-aminoethylamino)phenol, o-(2-pyridyl- methylamino)phenol, N-(2-aminoethyl)glycine, N-(2-pyridylmethylamino)glycine, N-(3-hydroxyl-2-pyridyl- methylamino)glycine, 2-aminomethyl-l-methyl-4-imidazolecarboxylic acid, or another tridentate dye moiety.

In a preferred embodiment of this invention, Lig in the above formula is another dye moiety of the structure illustrated above. This results in a 2:1 dye:metal complex having the following structural formula:

wherein each X, Z, R, CAR, n and Me is as defined above.

Preferably, X represents the atoms necessary to complete an unsubstituted or a substituted quinoline, quinoxaline, indolenine or benzimidazole ring. In another preferred embodiment, X represents the atoms necessary to complete a quinoline ring, Z is alkyl and R is CN. In a further preferred embodiment, CAR is attached to the 5-position of a quinoline ring.

Z and L in the formula and definition described above can be any alkyl or aryl group (including substituted alkyl or aryl groups) as long as the diffusibility of the dye moiety is not encumbered. Good results are obtained with alkyl or substituted alkyl groups having from 1 to 12 carbon atoms, such as methyl, ethyl, isopropyl, t-butyl, pentyl; arylalkyl groups having from 7 to 13 carbon atoms, such as benzyl; alkoxyalkyl groups having from 2 to 12 carbon atoms such as methoxyethyl; aryloxy alkyl groups having from 7 to 13 carbon atoms such as phenoxyethyl or alkoxy carbonylalkyl groups having from 3 to 12 total atoms such as ethoxycarbonylmethyl; or aryl or substituted aryl groups having from 6 to 12 carbon atoms such as phenyl, alkoxyl- phenyl, tolyl, carboxyphenyl, sulfamoylphenyl or naphthyl.

In another embodiment of the invention, CAR may have attached thereto two azo dye moieties in which case two dye moieties will be released from one CAR moiety.

Other substituents may also be present in the rings illustrated above, such as alkyl or acyl of 1 to 6 carbon atoms, aryl of 6 to 10 carbon atoms, aralkyl of 7 to 12 carbon atoms, alkylsulfonyl or alkoxy wherein the alkyl moiety has from 1 to 6 carbon atoms, halogens such as chloro or bromo, amino, morpholino, phenylsulfamoyl, solubilizing groups such as sulfonamido, sulfamoyl, carboxy, sulfo or hydrolyzable precursors thereof.

Compounds useful in this invention can be prepared by reaction of B-ketonitriles or B-dicarbonyl compounds with diazotized 8-aminoquino- line, 5-amino pyrazine or like derivatives.

There is great latitude in selecting a CAR moiety which is attached to the dye-image-providing compounds described above. Depending upon the nature of the ballasted carrier selected, various groups may be needed to attach or link the carrier moiety to the dye. Such linking groups are considered to be a part of the CAR moiety in the above definition. It should also be noted that, when the dye moiety is released from the compound, cleavage may take place in such a position that part or all of the linking group, if one is present, and even part of the ballasted moiety, may be transferred to the image-receiving layer, along with the dye moiety. In any event, the dye nucleus as shown above can be thought of as the minimum which is transferred.

CAR moieties useful in the invention are described below:

Representative image-providing RDR compounds useful in this invention include the following:

Compound 1

Compound 2

Compound 3

Compound 4

Compound 5

Compound 6

Compound 7

wherein CAR is

Compound 8

wherein R⁸ is

Compound 9

wherein R⁹ is

A process for producing a photographic transfer image in color utilizing photographic recording materials as described herein comprises:

• (a) treating such a recording material with an alkaline processing composition in the presence of a silver halide developing agent to effect development of each exposed silver halide emulsion layer;
• (b) the dye-releasing compound then releasing the diffusible azo dye imagewise as a function of the development of each of the silver halide emulsion layers; and
• (c) at least a portion of the imagewise distribution of the azo dye diffusing to a dye image-receiving layer to form a metal-complexed azo dye transfer image.

The above-described metal-complexed azo dye transfer image formed in the receiving layer contains a photographic mordant to bind the dye or coordination complex thereto. The coordination complex so bound has the structural formula:

wherein X, Z, R, Lig and Me are as defined above.

The photographic recording material usually contains a photographic mordant or image-receiving layer to bind the dye or coordination complex thereto.

After processing the photographic recording material described above, there remains in it, after transfer has taken place, an imagewise distribution of azo dye in addition to developed silver. A color image comprising residual nondiffusible compound is obtained in this recording material if the residual silver and silver halide are removed by any conventional manner well known to those skilled in the photographic art, such as a bleach bath, followed by a fix bath or a bleach-fix bath. The imagewise distribution of azo dye may also diffuse out of the recording material into these baths, if desired, rather than to an image-receiving element. If a negative-working silver halide emulsion is employed a positive color image, such as a reflection print, a color transparency or a motion picture film, is produced in this manner. If a direct-positive silver halide emulsion is employed a negative color image is produced.

The photographic recording material in the above-described process can be treated in any manner with an alkaline processing composition to effect or initiate development. The recording material may also comprise a dye image-receiving layer.

The alkaline processing composition and means containing same for discharge are preferably contained within the recording material. There can be employed, for example, a rupturable container which is adapted to be positioned during processing so that a compressive force applied to the container by pressure-applying members, such as would be found in a camera designed for in-camera processing, will effect a discharge of the container's contents within the recording material.

The concentration of the dye-releasing compounds that are employed in the present invention may be varied over a wide range, depending upon the particular compound employed and the results which are desired. For example, the dye-releasing compounds may be coated in layers at a concentration of 0.1 to 3 g/m² by using coating solutions containing between 0.5 and 8 percent by weight of the dye-releasing compound distributed in a hydrophilic film-forming natural material or synthetic polymer, such as gelatin or polyvinyl alcohol, which is adapted to be permeated by aqueous alkaline processing composition.

Preferably, the silver halide developer or electron transfer agent (ETA) employed in the process becomes oxidized upon development and reduces silver halide to silver metal. The oxidized developer then cross-oxidizes the dye image-providing compound. The product of cross-oxidation then undergoes alkaline hydrolysis, thus releasing an imagewise distribution of diffusible azo dye which then diffuses to the receiving layer to provide the dye image. The diffusible moiety is transferable in alkaline processing composition either by virtue of its self-diffusivity or by its having attached to it one or more solubilizing groups, for example, a carboxy, sulpho, sulphonamido, hydroxy or morpholino group.

The term "nondiffusing" used herein has the meaning commonly applied to the term in photography and denotes materials that, for all practical purposes, do not migrate or wander through organic colloid layers, such as gelatin, in the photographic recording materials of this invention in an alkaline medium and preferably when processed in a medium having a pH of 11 or greater. The same meaning is to be attached to the term "immobile". The term "diffusible" has the converse meaning and denotes materials having the property of diffusing effectively through the colloid layers of the photographic recording materials in an alkaline medium. "Mobile" has the same meaning as "diffusible".

The term "associated therewith" is intended to mean that the materials can be in either the same or different layers, so long as the materials are accessible to one another.

The following examples are provided to further illustrate the invention.

Example 1 -- Released Dyes--Spectra, Light Stability and Dye Diffusion Tests

A receiving element was prepared comprising a poly(ethylene terephthalate) film support having thereon a nickel sulfate hexahydrate (0.58 g/m²)/gelatin (1.08 g/m²) metal complexing layer, and a poly(4-vinylpyridine)/gelatin mordant layer (each at 2.15 g/m^l), which forms metal complexes with the unmetallized dyes.

An alternative receiving element was used with the premetallized dye-complexes. It comprised a poly(ethylene terephthalate) film support having thereon a layer of gelatin (1.1 g/m²) and a cationic mordant layer of poly(styrene-co-1-vinylimidazole-co-3-benzyl-l-vinylimidazolium chloride) (50:40:10) (4.5 g/m²) and gelatin (2.2 g/m²).

These receiving elements were immersed in alkaline solutions of the azo dyes listed below in Table I. The elements were then removed from the dye solutions, washed in distilled water, placed in a pH 7.0 buffer solution and dried. Transmission spectra obtained on each receiving element of the mordanted dyes were normalized by computer to a density of 1.0. The characteristic wavelength of the dye, λ1/2 in nm, is the mean of the wavelength limits of absorption at half the maximum density. The HBW ("half band width") in nm is the range or distance between those limits. The dye solution spectrum in 3:1 dioxane:water at pH 7 in the presence of excess nickel ion is also given.

The above receiving elements at pH 7 were then subjected to 10 days irradiation by a high intensity daylight (HID), 6000W Xenon arc lamp, each element receiving 50,000 lux through a Wratten 2B (ultraviolet) filter at 38°C. The percent fade represents the loss in density at λ_max after irradiation.

Dye Diffusion Tests

Various dyes in Table I were also subjected to the conditions of different dye diffusion tests. One, the "solution test", involved dissolving each dye in a viscous composition and transferring it through a receiving element which contains opaque and reflecting layers in addition to the mordant layer. The other, a "gel pad test" involved imbibing the dye from solution into a thick gelatin layer, and then transferring it by direct lamination to the same receiving element which had been preswollen by soaking 5 minutes in a solution of 0.1 potassium hydroxide. The receiver for these tests had the following composition (coverages are parenthetically given in g/m²):

• A transparent poly(ethylene terephthalate) film support coated with
• 1) a mordant layer of poly(styrene-co-N-vinylbenzyl-N-benzyl-N,N-dimethylammonium chloride-co-divinylbenzene) (weight ratio 49.5:49.5:1) (2.28) and gelatin (2.28);
• 2) an opaque layer of carbon black (1.88) in gelatin (1.23);
• 3) a reflecting layer of titanium dioxide (16.1) in gelatin (2.63); and
• 4) an overcoat layer of gelatin (4.3).

Solution Test

Approximately 0.075 mmol of the released dye was dissolved in 10 ml of 0.125 N potassium hydroxide. After the dye was completely dissolved, 20 ml of a viscous composition was added; and the resulting solution, stirred for at least 20 minutes, was 0.0025 M in dye at a pH of 13.4. The viscous composition was prepared from 46.2 g potassium hydroxide and 54 g carboxymethylcellulose dissolved in 1200 ml water. The dye solution was then spread between the receiver and a clear polyester cover sheet. This "sandwich" was then passed between spaced rollers so that the gap containing the viscous solution had a thickness of 102 µm. Measurement of the rate of dye diffusion was commenced at the point at which half of the sandwich, or laminate, had passed through the rollers. The appearance of dye on the mordant was measured at À max as diffuse reflection density vs. time. The reflection density was converted to transmission density. A plot of transmission density, which is proportional to concentration vs. time, was derived. Calculation was made of the value of t-1/2 of dye transfer, the time in seconds required to obtain one-half of the maximum transmission density.

Gel Pad Test

A donor element, containing a thick pad of deionized acid-processed gelatin (26 g/m²) hardened with 2 percent bis(vinylsulfonylmethyl)ether, was imbibed with a solution of 0.1 M in potassium hydroxide and 1.3 X 10-³ M in dye. The pad was soaked to full penetration, surface wiped, and then laminated in direct contact to the above receiving element which had been presoaked for 5 minutes at 0.1 M KOH. The t-1/2 of dye transfer was obtained as in the solution test. The diffusion times by the "gel pad test" are substantially longer than by the "solution test".

Example 2 -- Photographic Test

A photographic element was prepared by coating the following layers in the order recited on a transparent poly(ethylene terephthalate) film support. Coverages are parenthetically given in g/m² unless otherwise stated.

• 1) Layer of compound identified below in Table 2 (2.2 X 10^-4 moles/m²) in 1/2 its weight of diethyllauramide, scavenging agent potassium 5-s-octadecylhydroquinone-2-sulfonate (0.022) and as a blocked developing agent 1-phenyl-2-pyrazolin-3-yl-N-methyl-N-[2-(N-methyltrifluoroacetamidomethyl) -4-(_B-sulfonamido)-phenyl]carbamate (0.54) in gelatin (2.8);
• 2) Blue-sensitized silver chloride emulsion (0.39) in deionized gelatin (0.86), 1-(m-acetamidophenyl-2-tetrazoline-5-thione (350 mg/mole Ag), and octadecylquinone (5 g/mole Ag); and
• 3) overcoat layer of 2,5-di-s-dodecylhydro- quinone (0.32) in deionized gelatin (0.54).

A receiving element was prepared by coating a mordant layer of a mixture of poly(N-vinylimidazole) (1.6 g/m²) and gelatin (1.6 g/m²) coated over a gelatin layer (0.81 g/m²) on a polyethylene-coated paper support.

The photographic element was given a full exposure to D _max then soaked for 15 seconds in an activator containing, per liter of developer: 33.7 g potassium hydroxide, 2.0 g potassium bromide, 3.0 g 5-methylbenzotriazole, and 2.0 g 11-aminoundecanoic acid. The photographic element was then laminated to the receiver. The laminate was then cut into four pieces and placed on a constant temperature (24°C) block. The four receiver pieces were peeled off after 1, 3, 5 and 10 minutes, each dried, and the Status A density recorded. The access time, taken as the first of the strips to achieve a constant density on the receiver, was measured as follows:

Synthesis of RDR Compound 1

To a 1 liter round-bottom flask was charged 350 ml tetrahydrofuran (THF) and 35.0 g (0.0301 mole) of RDR Compound X (see synthesis below) under a nitrogen atomosphere. To this stirred solution was added 100 ml absolute ethanol and, slowly, 3.74 g (0.01505 mole) nickel acetate [Ni(OAc)₂·4H₂O] dissolved in 20 ml water. The solution was stirred overnight at room temperature under nitrogen. The reaction mixture was heated at reflux for 8 hours, causing the conversion of unreacted material into the 2:1 complex. The reaction mixture was then concentrated to less than 1/2 volume in vacuo and chilled to deposit a dark brown oil. As much as possible of the supernatant liquid was decanted. Acetonitrile (CH₃CN) was added to the oil until a crude product had solidified. The product was filtered and air dried.

Some 1:1 complex still present was readily removed by dissolving the crude product in a minimum amount (250 ml) of ether and passing through a 15 cm X 15 cm (diameter X height) pad of dry (unsolvated) Woelm silica gel, and washing with ether until all of the product had eluted. The ether solution was then brought to a boil, 500 ml acetonitrile added and the volume reduced to about 700 ml. The resultant cloudy solution was chilled overnight at 5-10°C and a precipitated amorphous solid recovered by filtration. Yield 31.0 g, e(3:1 dioxane-H₂O)= 5.76 X 10'.

Synthesis of RDR Compound 2

Compound 2, comprising two different dye moieties and having a 2:1 dye to nickel ratio, was prepared from the diaquo-acetato 1:1 RDR Compound Q below. The 1:1 complex (2.0 g, 1.52 mmole) and the released dye, Compound C (0.74 g, 1.57 mmole), were dissolved in 20 ml tetrahydrofuran and 0.5 ml glacial acetic acid and stirred 48 hours at room temperature. After evaporation of solvent, the crude product was chromatographed on silica gel, eluting with ether. The appropriate fractions were combined and rechromatographed on silica gel, eluting with di- chloromethane/acetic acid (gradient from 100:0 + 80:20). The appropriate fractions were combined, the solvent evaporated and the residue recrystallized from dichloromethane to yield 0.85 g of the desired product as a yellow-brown powder, ε⁴⁶⁰= 5.72 (3:1 dioxane-pH 6 buffer).

Analysis:

Calculated: (C₈₅H₁₀₉N₁₃O₁₂S₄Ni)

%C= 60.3, H= 6.4, N= 10.8, Ni - 3.4 Found: %C = 60.0, H = 6.4, N = 10.9, Ni - 3.4 Intermediates -- Synthesis of 1:1 Nickel Complexed

RDR Compound Q

A solution of 10.4 g (0.0418 m) nickel acetate tetrahydrate in 40 ml water was diluted with 200 ml ethanol and 100 ml tetrahydrofuran. A previously prepared solution of 4.85 g (0.00417 m) RDR Compound X in 75 ml tetrahydrofuran was added to the nickel acetate solution dropwise over 20 minutes. The reaction mixture was stirred at room temperature under a nitrogen atmosphere for 48 hours, concentrated in vacuo to approximately 1/2 volume and diluted with 500 ml ethyl ether. The resulting solution was extracted five times with 50 ml portions of water, dried (MgSO₄) and concentrated to 50 ml. The crude product was a mixture of the desired 1:1 complex and the corresponding 1:2 (Ni:RDR) complex. Purification was effected by chromatography on silica gel, eluting, first with ether, followed by a gradual change to THF:ether (2:3). The 1:2 complex (1.0 g) eluted first, followed by the desired 1:1 complex (2.5 g), which was isolated as a yellow-brown amorphous solid. ε= 2.39 X 10⁴ (3:1 dioxane-pH 6 buffer).

Analysis:

Calculated: (C₆₈H₁₀₁N₇O₁₁S₂Ni)

7C = 62.1, H = 7.7, N = 7.5, Ni = 4.4 Found: %C = 64.7, H = 8.2, N = 8.2, Ni = 4.4

Synthesis of RDR Compound X

Under a blanket of nitrogen, 4.31 g (0.005 m) of 4-m-aminobenzenesulfonamido-N,N-dioctadecyl-1-hydroxy-2-naphthamide was dissolved in 25 ml tetrahydrofuran (THF). To this solution was added 1.77 g (0.00525 m) of 2-(5-chlorosulfonyl-8-quinolylhydra- zono)acetoacetonitrile and 0.79 g (0.01 m) pyridine. The reaction mixture (nonhomogeneous) was stirred at room temperature for 20 hours and at 45-55°C for an additional 20 hours. The THF was removed in vacuo and the residue partitioned between 25 ml about 0.6 N hydrochloric acid and 50 ml ethyl acetate. The layers were separated and the organic phase washed three times with 15 ml 10 percent hydrochloric acid and three times with 10 ml water. The ethyl acetate solution was dried (MgSO₄), passed through a 0.63 cm silica gel pad and evaporated to yield a greenish-orange oil. This crude product was crystallized three times from methanol (300 ml), chromatographed (silica gel, ether-pentane) and recrystallized from methanol. Yield 1.5 g yellow powder ε⁴⁵⁵ (pyridine + Ni²⁺)= 2.7 X 10".

Intermediates:

A. 2-(5-Chlorosulfonyl-8-quinolylhydrazono)acetoaceto nitrile

To a 250 ml round-bottom flask fitted with a calcium sulfate drying tube was added 4.5 g (0.0126 m) of 2-(5-sulfo-8-quinolylhydrazono)acetoaceto- nitrile, potassium salt, and 45 ml phosphorus oxychloride. The resultant slurry was chilled to <5°C and 4.5 ml N-methylpyrrolidinone was slowly added. After stirring 1 hour at û-5°C, the slurry was stirred overnight at room temperature followed by quenching in 500 ml ice water. The resultant yellow solid was collected, air dried and recrystallized from 100 ml acetonitrile. Yield 3.0 g yellow needles (70 percent).

B. 2-(5-Suifo-8-quinolylhydrazono)acetoaceto nitrile, potassium salt

A slurry of 1.1 g (0.005 m) 8-amino-5-quino- linesulfonic acid in 20 ml water and 10 ml ethanol was treated with 2 ml concentrated hydrochloric acid and chilled to <5°C. To this yellow-orange slurry was added, slowly and dropwise, 5.0 ml of a 1 M sodium nitrite solution. After stirring for 15 minutes at 0-5°C, the colorless slurry was added slowly to a solution of 0.8 g (0.0075 m) of the sodium salt of cyanoacetone in 30 ml water containing 2 g of triethanolamine at 0-5°C. Additional triethanolamine was added during the addition to maintain a pH of about 8. After stirring at 0-10°C for 1 hour, the reaction was acidified with 5 ml glacial acetic acid and diluted with 50 ml saturated KC1. After settling at 0-5°C for 2 hours the slurry was filtered and the crude product recrystallized from 75 ml 0.2 M KC1. The yield was 1.0 g (56 percent), ε⁴⁴⁰= 2.72 X 10" (1:1 Dioxane-H₂0 ⁺ Ni₂+₎.

C. 8-Amino-5-quinolinesulfonic acid

To a 2-liter, 3-necked round bottomed flask fitted with a reflux condenser were charged 97.2 g (0.4 mole) 8-hydroxy-5-quinolinesulfonic acid, sodium bisulfite (83.2 g, 0.8 mole), 400 ml distilled water and 200 ml concentrated aqueous ammonia. The resulting slurry was heated at reflux for 88 hours during which time the reaction mixture became a clear orange solution. After cooling to room temperature, the reaction was acidified (20 ml conc. hydrochloric acid), chilled and filtered. An additional 10 ml conc. hydrochloric acid was added to the filtrate which was chilled and filtered. The combined air dried filter cakes were dissolved in 300 ml pyridine, chilled in an ice bath and 60 ml acetic anhydride added dropwise. The solid, which slowly precipitated following the addition, was isolated by filtration, washed with cold pyridine and THF and air dried to yield 48.8 g (35 percent) of pyridinium 8-acetamido-5-quinolinesulfonate.

In a 250 ml 1-neck round-bottomed flask fitted with a reflux condenser was placed 25.0 g (0.0724 m)of the pyridinium 8-acetamido-5-quinoline- sulfonate and 30 ml water. The slurry was heated to effect solution, 30 ml concentrated hydrochloric acid added and the mixture heated to reflux for 1 hour with stirring. A thick crystalline mass separated during the heating period. The thick slurry was then chilled to 0-5°C for three hours, filtered and washed with cold 6 N hydrochloric acid and THF. The yield was 11.3 g (70 percent) of product as off-white needles.

Example 3 -- Comparison with the Prior Art

In U.S. Patent 4,148,643, Compound J in column 32 is the nickel complex of the following dye compound:

The nickel-dye complex is listed as having a λ_max of 462 nm and a half-band width of 76 nm when adsorbed to a cationic polymeric mordant on a film strip. A 1:1 dioxane/water mixture at pH 7.0 of this nickel-dye complex was prepared. It absorbed at 444 nm in the presence of excess nickel ions and 402 nm in the absence of nickel ions.

In Table I, Compound C has the following structure:

The compound has a quinoline nitrogen chelating group instead of a hydroxyl chelating group as in Compound J of the '643 patent. A 1:1 dioxane/water mixture at pH 7.0 of the above Compound C was prepared. It absorbed at 452 nm in the presence of excess nickel ions and at 387 nm in the absence of nickel ions.

When the nickel ion concentration was reduced to one-half the molar concentration of the dye, Dye C showed no change in the spectrum, while Compound J of the '643 patent had a broad spectrum with a peak at about 418 nm.

The spectrum of Dye C in 0.5 mol Ni ++ appears to be a stable 2:1 complex of dye to metal, while the spectrum of Compound J of the '643 patent appears to be a mixture of nickel complex and unmetallized dye ligand. The spectral evidence thus shows that Dye C forms a much more stable 2:1 dye:nickel complex than compound J of the '643 patent.

The spectral and diffusion data for Compound C', the 2:1 dye:nickel complex of Compound C, is shown in Table I. However, efforts to prepare a similar 2:1 complex of compound J of the '643 patent failed. Only a 1:1 complex could be prepared.

When the unmetallized dye ligand of Compound J of the '643 patent and the 1:1 complex thereof were subjected to the gel pad diffusion test as described in Example 1, the values obtained were 66 sec. and 146 sec., respectively. The spectrum of the dyes on the receiver was measured and in both instances, however, only showed the presence of the unmetallized dye. The 1:1 dye:nickel complex of Compound J of the '643 patent decomposed under the conditions of transfer. Compound C', however, underwent no demetallization nor breakdown of the dye:metal complex under the same conditions of transfer.