CA1259515A - Photographic elements and processes utilizing imagewise reduction of ferric ions - Google Patents

Abstract

PHOTOGRAPHIC ELEMENTS AND PROCESSES UTILIZING
IMAGEWISE REDUCTION OF FERRIC IONS
Abstract of the Disclosure A process for obtaining highly stable color photographic images utilizes a silver halide photographic element comprising an essentially colorless, immobile compound which is capable of complexing with ferrous ions to form a dye. The complexing compound contains a complexing moiety which is represented by the formula:

Description

--1~
PHOTOGRAPHIC ELEMENTS AND PROCESSES UTTLIZING
IMAGEWISE REDUCTION OF FERRIC IONS
Rela~ed_A~lica-tions Reference is made to the following related S commonly assigned patents: U.S. Patent No. 4,555,478 by J.A. Reczek and J.M. Palumbo; U.S. Patent No.
4,555,477 by W.N. Washburn; and U.S. Patent No.
4,557,998 by W.N. Washburn and K.R. Hollister.
Fiel~_of the Invention The invention relates to color photography.
In particular, it relates to an imaging process for providing stable color images in photographic elements utilizing the reduction of ferric ions to ferrous ions. It also relates to photographic elements which can be used in this process.
Background of _he Invention It is well known in the photographic arts to record color images with photographic elements containing dye-providing materials which can be used to provide color images. Although the properties of dyes commonly used to provide such images (e.g. azo or azo-methine dyes) have been optimized over the years, there is a continued search in the art for dyes which provide images having improved stability to heat, humidity and chemical reagents.
Image formation based on metal chelate formation has generally been favorably regarded. The properties of the metal-ligand complexes can be manipulated by changes in both the metal and the complexing l:igand. A:lso, metal complex dyes a8 a class are considered to have excep-tional stability.
Complexes of ferrous ions and varlous chromophore ligands are known to be quite stable, some having formation constants ~pK) of from about 13 to about 24. SOTIe of these complexes have been traditionally ;
~ .

-2-used in an~lytical chemistry procedures where mere color form~tion is important rather than a particular color hue or speed of color formation.
Iron complexes have al~o been u~ed in imaging proces~es, for example to prepare "blue prints." In U.S~ Patent 1,776,155 (issued September 16, 1930 to Kogel), photographic images are obtained using light-sensitive ferric salt6 which are reduced upon exposure to light. The resulting ferrous ion6 complex wlth certain ketones to provide a bluish color image. These elements, however, 6uffer from poor speed, meaning that they are not light ~ensitive enough for modern photographic uses. Similar light sen~itive material~ are described in U.S. Patent 2,264,334 (issued December 2, 1941 to Schmidt).
U.S. Patent 3,660,092 (issued May 2, 1972 to Frank et al) relates ~o forma~ion of color images in photographie elements using heavy metal 6alt-dye complexes. Heavy met&l 6alt6 u6eful in the de6cribed elements include iron 6alts among many other6. In the embodiment using iron salts, a silver halide image is first converted to a mercury ~alt lmage which is then converted to ~n iron 6alt image which relea6es iron to react with a ligand to form a color dye image. '~is imaging process~ however, has several di6advantages. The use of iron complexes al~o require6 the use of mercury in the reaction sequence. Mercury is a potential contaminent in photographic 6ystems and should be avoided if po6sible. Further, the imaging proces6 described in thi~ reference is ba~ed on the conversion of silver halide to a metal complex, and involve~ a complex serie6 of proce6sing steps to obtain a negative image.
It would, therefore, be de~irable to form highly stable color images formed with dye precursor6 which are essentially colorless prior to imagewise exposure. It is al~o desired that the prOCeSE
providing such images would he simple and exhibit high sensitivity ~i.e. good speed~ ~o exposlng Actinic radiation.
Summary of the Invention The present invention provides a means for obtaining color image~ of exceptional ~tability. The dyes formed in the practice of this invention show desirable stability to a variety of environment~l conditions (e.g. heat end humidity) over an extended period. They also generally show improved stability to lighto Further, the process of this invention i6 simple to US2 in obtaining photographic images, and exhibits desired versatility in the placement of the dye precur60rs because they are essentially colorless until exposure to radiation. This invention utillzes complexes of ferrcu~ ionæ and certain essentially colorless and immobile compounds. The element6 used in the practice of ~his invention exhibit good speed (i.e. high sensi~iv1ty to expo~ing radiation~ and their use avoid6 the complicated imaging process taught in the Frank et al paten~ noted herein~bove.
The advantages of the present invention are obtainable because the essentlally colorless complexing compounds remain colorless until they come in contact with ferrous ions. These ions are provided by reduction of ferric ions which can be in the element or brought into contact with the element nfter imagewise expo~ure ~nd development. For example, imagewlse di~rlbuted si1ver met~l reduces the ferric lons, thereby providing ferrous ion~
available for imagewise complexing with the colorless compounds to form a dye.
Therefore, in nccordAnce with this invention, there is provided a process oE forming a ~p~

dye im~ge in an element comprising a support having thereon at least one silver halide emulsion layer which has associated therewith an essentially colorless~ immobile compound which is capable of complexing with ferrous ions. This complexing compound contains a complexing moiety which is represented by th~ structure:
R2 Rs ll ~3 Z - C-~S=N-C ~ =N-R4 (H)n (H)p wherein m is zero or a positive integer 1 to 3, n and p are independently 0 or l and -- represents a single or double bond. Z is Rl-N=, O~, S~, Rl-Pz, (Rl)2P- or (Rl)3P=, and when Z is (Rl)2P-, n is 1, otherwise n is 0. Rl, R2, R3, R4, Rs and R6 are independently hydrogen, amino, hydroxy, mercapto~ alkoxy, alkyl, aryl or a heterocyclic moietyv When R6 is 60 defined, p is 1 and -- is a single bond. If m ls 0, Rl and R2, R2 and R3, and R3 and R4 taken together can independently represent the carbon and heteroatoms necessary to complete a sub6tituted or unsubstituted carbocyclic or heterocyclic nucleus, or if m is 1 to

3, Rl and R2, Rs and R6, and R3 and R4 can independently represent the carbon and heteroatoms necessary to complete a sub6tituted or unsubstituted heterocyclic nucleus. When R5 and R6 are B0 defined, p is 0 when -- i8 a double bond, and p is l when -- ls a slngle bond.
The process of this invention compri~es the steps of forming an imagewise distribution of a reducing agent for ferric ions, reducing a ferric compound with the reducing agent to provide an imagewlse distribution of ferrous ions, and causing the ferrous ions to react with the complexing compound to form a ferrous ion complex dye.

~ his invention also provides an element comprising a support having thereon at least one silver halide emulsion layer which has associated therewith an essentially colorless, immobile complexing compound as described hereinabove.
_tailed Description of the Invention The advantages described hereinabove for this invention are attained because of the use of a particular class of essentially colorless, immobi'e complexing compounds. ~hese compounds can complex with ferrous ions to form useful stable dyes, such as cyan, magenta and yellow dyes useful in photographic products.
The complexing compounds useful in the practice of this invention are "essentially colorless", meaning that prior to complexation of the compound with ferrous ions to form a visible dye, the compound exhibits essentially no observable color.
That is, it generally exhibits a low optical density (i.e. less than about 0.05), although it may emit or reflect electromagnetic radiation in the non-visible portions of the electromagnetic spectrum. Therefore, the complexing compounds and the ferrous ions "form"
a colored dye from a colorless precursor, as opposed to compounds which are merely shifted in their absorption ~ma~ upon complexation with a ferrous ion to provide a dye of a different color.
-Generally, the dyes formed upon complexationof the co~pounds and ferrous ions are visibly co]ored dyes. That is, they absorb electroma~netic radiation in the visible portion oE the electromagnetic spectrum, i.e. between about ~00 and about 700 nm.
More than one molecule of a complexing compound can be complexed with one ferrous ion. For example, there may be two or three complexing compound molecules complexed with a single ferrous ion.

:
... :, ~2~ 5 Useful nonpolymeric complexing compound~ are ferroin type compounds such as hydrazones, tetrazolylpyridines, pyridylquinazoline6, bis-isoquinolines, imines, phenanthrolines, bipyridines, terpyridine~, bidiazines, pyridyldiazines, pyridylbenzlmidazoles, diazyltriazine~, o-nitrosoanilines and phenols, tetrazines, triazine~ described by Schilt et al in the journal Talanta, 15, pp. 475-478 (1968), pyridine derivatives of phenazine and quinoxaline described by Schilt et al in Talanta, 15, pp. 852-855 (1968), substituted benzimidazole derivatives as d~scribed by Schilt et al, Talanta, 15, pp. 1055-1058 (1968), oximes of substituted methyl and phenyl 2-pyridyl ketones as described by Schilt et al, Talanta, 16, pp. 448-452 (1969), and the like. Other complexing compounds are de6cribed in the following Talanta literature articles: 16, pp. 519-522 (1969), 13, pp.
895-902 (1966~, 17, pp. 649-653 (1970), 19, pp.
1025-1031 (1972), 21, pp. 831-836 (1974), 22, pp.
915-917 (1975), 23, pp. 543-545 (1976), 24, pp.
~85-687 (1977), 26, pp. 85-89 (1979), pp. 863-865 (1981), 36, pp. 373-376 (1979), 55, pp. 55-58 (1980), 29, pp. 129-132 (1982), and in Blsndamer et al, J.
Chem. Soc. Dalton, pp. 1001-lOQ8 (1978), Ca0e, J.
, 31, pp. 2398-2400 (1966) and U.K. Patent 701,843 (publi~hed January 6, 1954). The terpyridines are particularly u6eful for obtaining magenta dyes.
The nonpolymeric complexing compound can have a balla~t group which render6 it nondiffusible in the photographic element during proce6sing. The ballast group i6 generally an organic group of such molecular 6ize and configuration a6 to render the compound nondiffusible in a photographic element during development in an alkaline proce66ing composition. Particul~rly useful ballast groups include long chaln alkyl group~ (e.g. 6 to 30 carbon atoms~, as well as aromatic groups (phenyl, naphthyl) along with alkyl group6. Representative ballast groups include -CO-Cl lH2 3 ~ -Co-c6H4 (t-Cl 2H2 5), -CON(Cl2H2 5) 2.

-NHSOzCl6H33~ -C7Hl 5, --~ 3--NHS02Cl6H33, -S02NHCl8H3 7, -OCl 2H2 5 ~

/C l aH 3 7 ~<S03H C~2CH2SO3~Na .
Alternatively, the complexing compound can be a polymer chain which has one or more complexing moieties attached to the polymer backbone in a suitable manner. These polymer6 are bulky enough to be immobile in a coated layer, i.e. they are self-ballasting.
Polymer~ to which complexing moieties can be ttached are those having reactive groups that readily react with complementary reactive groups on a nonpolymeric complexing compound or are polymerized from monomer~ containing such moieties. For example, groups which easily undergo condensation re~ctions are quite useful. Acid derivative~ lncluding free carboxylic acids, ~cid chlorides and ~hydride6 readily condense with hydroxy, amine, and mercapto groups to split out ~mall molecules and form the desired monomer or polymer condensation product. The same can be accomplished with addition reactions, e.g. a hydroxy or amine group Adds readily to an i60cyanate group to form urethane or ureylene 12S~5 linkages, or an activated unsaturated group (acryloyl) adds readily to an amine group, or by any other reactions known in the art. The monomers can then be poly-merized to form the polymers usinq conventional polymerization techniques. Thus, any polymers or monomers, preferably vinyl polymers or monomers, containing requisite reactive groups complementary to reaction groups on the nonpolymeric complexing compound to be attached to the polymer are useful in forming polymeric complexing compounds or monomers useful in making same. Polymers and monomers containing carboxylic acid, carboxylic acid halides, carboxylic acid anhydride, sulfonic acid, hydroxy, epoxy, amino, isocyanate, etc. groups are especially useful. More specifically, copolymers of acrylic acid, methacrylic acid, maleic anhydride, 2-hydroxyethyl acrylate, glycidyl methacrylate, and the like, have useful reactive groups. The preparation and properties of such polymers are given in various polymer textboo~s such as M. P. Stevens Polymer Chemistry An Introduction, Addison-Wesley Publishing Co., Inc., Reading, Mass. (1975) and W. R.
Sorenson and T. W. Campbell, Preparative Methods of Polymer Chemist~y, 2nd Ed., Wiley, New York, New York (1968). Comonomers useful in preparing the complexing compounds can be any that are compatible with the preparative reactions involved and whose substituents do not interfere with the photographic process. Acrylamide, acrylam:ide derivativc?s arld other hydrophilic comonomer.s are partlcular1y use~ul.
Example 8 below illustrates a speciEic polymeric complexing cornpound which contains a moiety which complexes with ferrous ions to form a magenta dye.

~ ~ .

~5~5~
g Particularly useful complexing compounds (polymeric or nonpolymeric) have complexing moieties which are repres~nted by the structure:
R2 Rs I K3 1 1 ll I
Z - C-~C'N-C ~ -N-R4 (H)n (H)p wherein m is 0 or a po6itive integer 1 to 3, n and p are independently 0 or 1, and -- repre~ents 8 single or double bond. Z is Ri-N=, Oe, S-, R~-P=~ ~RI)2P- or (Rl)3P=, and when Z
is (Rl)2P-, n is 1, otherwise n is 0.
Preferably, m is 0 or 1 and Z is Rl-N=.
Rl ~2 ~3 R4, Rs ~nd R6 are independently hydrogen, amino (primary, second~ry or tertiary), hydroxy, mercapto, alkoxy (preferably of 1 to 20 carbon atoms, e.g. methoxy, chloromethoxy, ethoxy~ octyloxy, alkoxy 6ubstituted with imino, etc.), alkyl (preferably of 1 to 20 carbon atoms in the nucleu~, e g. methyl, ethyl, chloromethyl, isopropyl, t-butyl, heptyl, alkyl sub~tituted with imino, etc.), aryl (preferably of 6 to 14 carbon atoms, e.g. phenyl, naphthyl, xylyl, ~-methoxyphenyl, aryl ~ubstituted with imino, etc.), or a heterocyclic moiety (preferably having 5 to 20 carbon, nitrogen, sulfur or oxygen atoms in the nucleus, e.g. pyridyl, quinolyl, a heterocycle ~ubstituted with imino, etc.). In 60me embodiments, Rl and R4 are not hydroxy.
When R6 i6 a group defined above, p i~ 1 and -- i8 a ~ingle bond.
Alternatively, if m i6 O, Rl and R2, R2 and R3, and R3 and R4, taken together, can independently repre6ent the carbon and heteroatoms (e.g. nitrogen, oxygen, 6ulfur, 6elenium, etc.) 5~5 nece6sary to complete a sub~itu~ed or un6ub~tituted 5 to 20 membered mono- or polycyclic carbocyclic or heterocyclic nucleus (e.g. pyridyl, quinolyl, trlazinyl, phenanthrolinyl, pyrimidyl~ etc.). The heterocyclic nucleu6 60 formed can he ~ubstituted with one or more oxo~ ~lkyl, amino, imino, aryl, phosphino (e.g. diphenylphosphino~, alkoxyJ amide, 6ulfonamide, thio or sulfo groups a~ defined above or a heterocyclic group (e.g. pyridyl, pyrimidyl, thiazolyl, imidazolyl, thienyl, etc.3.
If m is 1~ 2 or 3, Rl and R2, R5 and - R6, and R3 and R4, taken together, can represent the carbon and heteroatom6 (e.g. nitrogen, oxygen, sulfur, selenium, etc.) necessary to complete a substituted or unsub~tituted 5 to 20 membered mono- or polycyclic heterocyclic nucleus as defined above where m is 0. When R5 and R6 ~re so defined, p is 0 and when -- i6 a double bond, ~nd p is 1 when -- is a single bond.
Example~ of useful complexing compound~
which form color dyes with ferrous ions are shown below. The ~max of each re6ulting ferrou~ ion complex dye is al~o noted.

H2N - N ~ C - C - N - NH2 yellow, AmaX~ 442 nm;

HlsC7 C7Hl 5 H2N - N - C - C ~ N - NH2 yellow, ~mRx~ 443 nm ~ li yellow, ~mRx' 441 nm;

~3C CH3 H3C - N - C - C ~ N - CH3 magenta, 1~maX~ 564 nm red ~ ~max 522 rlm ~ magenta, AmaX= 552 nm ~N/ ~N/ ~N

N~ ~N/ ~N/ magenta~ ~max~ 557 nm /- ~ /NHS02C 1 6H 3 3 \.~
/-~. ~-\. ~-\
magenta ~ Amax~ 571 nm C I ~H 3 7 1~

N/ ~N/ magenta, AmaX- 567 nm ~-~ /OC8Hl 7 HO3S~
\,~

11 t 11 magenta, ~ - 583 nm N~ ~N/ ~N/ max li -t--5O3H magenta, ~max 557 nm \.~

PolymerB represented by the recurring unit~:

-~c~2-clH)x-~cH2-cH- )y(CH2~C ~
CONH2 CONHCH2CH20 CONH--~CH *3NH2-HCl i~ \ii i~ \il i~ \il ~ / ~N/ ~N/

wherein x i~ 0 to sbout 90 weight percent, y i8 from about 2 to about 60 weight percent, and z is 0 to about 40 weight percent.
magenta, ~m~x~ 561 nm wherein x 18 65, y i~ 30 ~nd z i6 5 H37Cl3 - N -CH2CH2SO3Na O~ NH cy~n~ ~max 644 nm N
OH

N~ / Y max N~2 ~ ~ cyan, ~max= 650 nm.
10 ~ H
N
OH
The complexing compound6 u~eful in the practice of this invention can be readily prepared using techniques known in the art. See, for example the Talanta references noted above as well as U.K.
Patent 701,843 relating to nonpolymeric compound6.
Polymeric compounds are easily prepared a6 described above using conventional synthetic methods.
Representa~ive 6yntheses of useful complexing compounds are described in Example6 1, 5 and 7 below.
As noted above, the de6cribed complexing compound i6 capable of complexing with ferrou6 ion6 to form a highly stable dye in one or more layer6 of a photographic element. In general, the log of the formation con6tant of such complexes is in the range of from about 10 to about 30, and preferably from about 15 to about 25.
The proce6s of this invention can be used to generate A variety of types of colored image6. For example, the process can be u6ed to generAte color images in conventional photographic element6 which utilize 6ilver halide e.g. color paper6, color film6, diffusion transfer elements, and the like, the detailed de6cription of which are within the skill of 2~ 5 an ordinary worker in the photographic art ~see, e.g.
Research Disclosure publications 15162 and 17643 ~ . . .._ _ noted below.
The process of this invention is carried out by physicslly contacting the ferric compound with an imagewise distribution of silver. ~or example, the process can be accomplished with an element comprising a 6upport having thereon at lea~t one silver halide emul6ion layer which ha6 associated therewith a complexing compound as de6cribed above.
The process comprise~ the steps of:
imagewise exposing and developing the silver halide emulsion layer to provide ~n imagewise distribution of metallic silver, physically contacting the metallic silver with a ferric compound, thereby reducing the ferric compound and providing an imagewise pattern of ferrous ions, and causing the ferrous ions to react with the complexing compound to form a ferrous ion complex dye.
In this process, the ferric compound can be provided in a processing or other solution.
Alternatively, the ferric compound can be provided in a cover sheet which is applied to the element containing the complexing compound after or during imagewise development. The complexing compound is in the silver halide emulsion layer or in a layer associated therewith.
The photographic element~ of this invention can be processed by conventional technlques in which the proce6sing solutions or compositions ~re incorporated in the element or are separately applied in a solution or proces6 sheet. These solutions or compositions contain developing agents (e.g. color developing agents) and other conventional processing addenda. More specifically, processing of the ~5 ~

elements of this invention can be accomplished by conventional silver development, either color or black and white, for example, by treatment with a hydroquinone developer, followed by bleaching with an Fe+3 salt bleach.
Photographic elements of this invention generally comprise a support and one or more silver halide emul6ion layer6 and aæsociated dye-forming layers. The complexing compounds can be incorporated in one or more of the silver halide emulsion layer~
or in other layers, 6uch as adjacent layer~, associated with thP emulsion layers. The silver halide emulsion layer can contain, or h~ve associated with it, photographic coupler compounds 9 such as color forming couplers, colored masking couplers, etc. These coupler compounds can form dyes of the same or different color or hue as the dyes formed by complexation of complexing compound and ferrous ions. Additionally, the ~ilver hslide emulsion layer can contain other addenda conventionally contained in such layers.
In one embodiment~ a multilayer, multicolor photographic element comprises a support having thereon a red-sensitive silver halide emulsion unit having associ~ted therewith a fir~t es6entially colorless, immobile complexing compound described above which is capable of complexing with ferrous ions to form a cyan dye, a green-6ensitive silver halide emulsion unit having associated therewith a second essentially colorle6s, immobile complexing compound described above which iB capable of complexing with ferrou6 ions to form a magenta dye and a blue-sensitive silver halide emul~ion unit having associated therewith a third essentially colorless, immobile complexing compound de~cribed above which is capable of complexing with ferrous 25~5~lS

ions to form a yellow dye. Each 6ilver halide emulsion unit can be composed of one or more layer6 and the various unit~ and layer can be arranged in different loca~ions with re~pect to one another a6 iB
known in the art. The complexing compounds described herein can be incorporated into or a~sociated with one or more units or layers of the element. A
photographic color paper product is a particularly preferred embodiment of this invention.
Preferably, the second complexing compound in the sbove multilayer element is a polymer composed of recurring units having the structure:
-tCH2-CH~-! 1 1.1 1 ll ~ ~N ~N
The light sen6itive silver halide emul6ions can include coarse, regular or fine grain 6ilver halide cry~tals or mixtures thereof and can be comprised of ~uch silver halides a6 ~ilver chloride, silver bromide, silver bromoiodide, silver chlorobromide, 6ilver chloroiodide, silver chlorobromoiodide and mixtures thereof. The emulsions can be negative-working or direct-positive emulsions. They c~n form latent image6 predominantly on the surface of the silver halide grains or predominantly on the interior of the grAins. They can be chemically and spectrally een~itized. The emulsions generally are gelatin-containing emulsions although other natural or 6ynthetic hydrophilic colloids or mixtures thereof can be used if desired.
The element support can be any 6uitable ~ub6trate used in photographic element6. Examples of such support6 include films of cellulo6e nitrate, cellulose acetate~ poly(vinyl acetal), polyester6 [e.g. poly(ethylene terephthalate~]~ polycarbonates and other resinous material~, glsæs, metal6, paper, and the like. Generally, a flexible paper or resinous film support iB u6ed, and a paper 6upport is particularly useful. Paper ~UppOrtOE can be acetylated or coated with baryta and/or an ~-olefin polymer such as polyethylene, polypropylene, ethylene-butene copolymer and the like.
Further detail~ regarding silver halide emulsions and photographic elements, including diffusion transfer elements, are well known in the art as described, for example, in Reæearch Disclosure, publication 17643, December, 1978, as well as in Research Disclo_ure, publication 15162, November, 1976 and U. S. Patent 4,358,525 (i6~ued ~ovember 9, 1982 to Mooberry e~ al). Re6earch Disclosure i~ available from Kenneth Mason Publication6, Ltd., The Old Harbourma6ter'fi, 8 ~orth Street, Emsworth, Hampshire P010 7DD ~ngland.
The following example~ are provided to illustrate the practice of this invention.
Example 1 Cyan Dye ~ormation in Silver Halide Element The complexing compound, N-(4-hydroxy-5-nitro60-6-amino-2-pyrimidyl)-N-octadecyl taurine, disodium 6alt, was prepared according to the teaching in U.K. Patent 701,843 (Example 29) noted above. A coating compo~ition WA8 prepared and coflted on a tran~parent poly(ethylene terephthalate) substrate to form a donor element having 88 mg/m2 of the complexing compound, 1.3 g/m2 of gelatin and 13 mg/m2 of bis(vinylsulfonyl)methyl ether hardener.
A graduated density 6ilver ~tep-image was prepared on a 6imilar substrate. This 6tep-image wa6 obtained by exposing a conventional black-and-white ~5~ 5 ~5 photographic light-6ensitive element containing a ~ilver chlorobromide emulsion to a te~t object in a sensitometer and processing the re6ulting latent image in a conventional manner with developer, 6top and fix 601utions to obtain a negative image of metallic ~ilver. The analyzed silver on this ~tep-image ranged from less than 0.1 mg Ag/m2 in the Dmin (non-exposed) area to 19 mg Ag/m2 in the DmaX (exposed) area.
A ferric ion solution was prepared having the following composition:
ammonium bromide 150.0 g/l ferric ammonium ethylenediamine-tetraacetate 99.0 g/l ethylenediaminetetraacetic acid40.0 g/l acetic acid (glacial) 10.5 g/l potassium nitrate (pH adjusted to 6.0) 41.0 g/l.
The donor element wa6 60aked in the ferric ion 601ution contained in a shallow tray processor for 20 6econds at room temperature, and ~ub6equently laminated to the dry silver 6tep-image element between nip-rollers. After 60 6econds, the donor element was separated from the 6tep-image element and the step-image element was discarded. The ferric ions had migrated to the step-image element, were reduced and had migrated back a6 evidenced by cyan dye image formation in the donor element. The Status A density of the coating ran8ed from 0.05 in the Dmin area to 0.71 in the DmflX ~rea. The ~erric ion~ had been reduced to ferrous iOnB by metallic silver in the 6tep-image element, making tho6e ferrous ions available for complexing to form the cyan dye in imaged areasd s~ ~

Example_2 Cyan Dye_Formation in Silver Halide Element Containin~
Complexing Com~ound in Silver Halide Layer This example is like Example 1 except that the complexing compound is incorporated in the silver halide element rather than being supplied by a donor element.
A light-sensi~ive coating was prepared and coated on a transparent poly(ethylene terephthalate) support providing 0.83 g/m2 of the complexing compound described in Example 1, 0.26 g Ag/m 2 of unsensitized silver chlorobromide polydlsperse n~gative emulsion, 1.3 g/m2 gelatin and 13.0 mg/m2 of bis(vinylsulfonyl)methyl ether hardener.
This photosensitive element wa6 then exposed in a sensitometer through a graduated density step test ob~ect to give a full-scale im~ge. The element was then processed to a black-and-white silver image using convent~onal D-72 type developer, stop-bath and fixer solutions followed by wa~hing and drying. The resulting negative silver image had from less than 0.1 mg Ag/m2 in the Dmin area up to 20 mg Ag/m2 in the Dmax area-A cover sheet of 26 g/m2 unhardened gelatin on a ~imilar support was soaked in the ferric ion solution described ~n Example 1 for 20 ~econds at room temperature, and laminated to the proces6ed ~ilver-containing element between two nip-rollers.
After 60 ~econd~, the cover ~heet was separated from the element. The processed element, containing a cyan dye image was washed to remove residual ferric solution ~ fixed to remove residual silver halide, washed again and dried. The Statu~ A density range from 0.09 in the Dmin area to 0.84 in the DmAX
area.

Example 3 Cyan Dye Formation in Silver Halide Element Containin~
Complexing Compound ~n Layer Ad~acent Silver Halide Layer This example is ~imilar to Example 2 except that the complexing compound was coated (0.83 gtm2) ln gelatin (1.3 g/m2) in ~ ~eparate layer above the silver halide emul~ion layer. The re6ulting element was expo6ed and processed as in Example 2 to give a full-scale black-and-white 6ilver image. The processed element was dipped for 60 second6 in the ferric ion solution de~cribed in Example 1, w~hed, fixed, washed again and dried. The Status A density ranged from 0.08 in the Dmin area to 1.4 in the DmaX area. The step-image of thi~ element appeared visually sharp and well-defined.
Example 4 Stability Comparison of Cy~n Dyes This iB a compAri60n of the light ~nd d~rk 6tability of a cyan dye image formed with the practice of this invention to the light and dark stability of a cyan dye provided by a conventional coupler.
An element was prepared ~nd processed a6 described in Example 1. A 6tep area nearest to den6ity 1.0 in the processed element was incubated for three weeks and the decrease in densi$y wa~
c~lculated as a percent 106~ of the original dens$ty. The density 1088 data are pre~ented ln Table I below. The dark keeping incub~tion w~
carried out in two different temperRture ~nd relative humidity environment~ for three week6. The light 6t~bility was mea6ured by measuring the % dye 108 after the element had been expo6ed to a high intensity 5500K light ~ource (50 klx) for 21 day6 through a Wratten 2B filter.

A Control element was prepared by coating a similar pho~osensitive coating composition on a substrate, substituting the color-forming coupler 2-[~-(2,4-di-t-amylphenoxy)butyramido]-4,6-dichloro-5-methylphenol for the complexing compound. ~he element was developed with

4-amino-3-methyl-N-ethyl-N-~-(methane6ulfon~mido)ethy laniline. The processed element was incubated under the same conditions as above. The percent decrease in density at a step nearest an initial density of 1.0 was calculated. As the data in Table I
illustrates, the cyan dye formed wl~h the complexing compound according to the practice of this invention has significantly more dark keeping stability than the conventional cyan dye formed in the Control element.
Table I
% Density Loss % Dye Loss (Dark Stability) (Light Stability) Element 60C/70% R.H. 77C/15% R.H. 21 days Control 10 40 6.5 Example 4 1 5 12 Example 5 Magenta Dy_ Formation in Silver Halide Element The comple~ing compound 4'-(3-hexadecanesulfonamidophenyl)-2,2':6',2"-terpyridine w~s prepared in the following manner.
4'-(3-Nitrophenyl)-2,2':6',2"-terpyridine was prepared from 3-(3-nitrophenyl)-1-(2-pyridyl) 2-propenone ~s described by Krohnke in ~y~ iB, 13ff (1976). The terpyridlne compound (10 g) was suspended in 100 ml of tetrahydrofuran, 20 ml ethanol and 10 ml of triethylamine. After addition of 1.0 g 10% palladium on carbon, the mixture was hydrogenated at 40 psi (2.75 x 105 pasc~ls) for 6 hours. The solid aminophenylterpyridine reaction product was then obtained by filtration and evaporation of the solvent~

2~

This product (ll g) was dissolved in 200 ml of pyridine, and 11 g of hexadecane~ulfonyl chloride was added. The resulting mixture was ~tirred at room temperature for 20 hours and evaporated to drynes6.
The residue was dis601ved in 400 ml of ethyl acetate and washed several times with water. The ethyl acetate was then evaporated and the residue was dissolved in a minimum volume of dichloromethane, and ligroin was added to slowly precipitate the product.
Two additions of ligroin yielded a total of 15.9 g solid. Purification of the solid was done by column chromatogr~phy on silica gel using dichloromethane and dichloromethane:ethyl acetate 3:1 as eluting solvents.
A photosensitive element was prepared having a poly(ethylene terephthalate~ support and a photosensitive layer containing: 0.6 g/m2 of the complexing compound (di~persed in 1:1 N,N-diethylauramide and ethyl acetate), 0.26 8 Ag/m2 unsensitized silver chlorobromide polydisperse negative emul6ion, 1.3 g/m2 gelatin and 13 mg/m2 bis(vinylsulfonyl)methyl ether hardener. Cver the emulsion layer was coated a 1.1 g/m2 gelatin overcoat.
The resulting element was expo6ed to ~
graduated density 6tep test ob~ect and proce~sed a6 described in Example 2 except that the developer wa6 a conventional D-76 type. The resulting negative 6ilver im6ge had from 0.1 mg Ag/m2 in the Dmin area to 22.0 mg Ag¦m2 ln the DmaX area.
A cover 6heet containing 26 g/m2 unhardened gelatin on a transparent polyethylene terephthalate support was soaked for 60 second~ in the ferric ion solution and processed with the exposed element as de~cribed in Example 2. A magenta dye image wa6 observed in the expo6ed element ~5 ~

immediately. Af~er 5 minutes of lamination, the cover sheet was removed from ~he exposed element.
The Status A densîty of the mhgen~a dye image ranged from les6 than 0.15 in the Dmin area to lr4 in the

5 DmaX area.
Example 6 Stability Compari~on of Ma~enta Dyes Thi~ is a comparison of the li~ht &nd dark stability of the magenta dye image obtained with the element described in Example 5 to the light and dark 6tability of a magenta dye ob~ained with a conventional color coupler.
A conventional photosen6itive element wa6 prepared similarly to the element of Example 5 using the magenta-forming color coupler 1-(2,4,6-trichloro-phenyl)-3-(5-[~-(3-t-butyl~4-hydroxyphenoxy)-tetradecanamido]-2-chloroanilino)-2-pyrazolin-5-one and developer 4-nmino-3-methyl-N-ethyl-N-~-~methane6ulfonamidoethyl~aniline. The exposed and developed elements were evaluated for light and dark keeping stability as described in Example 4. The re6ults of the tests, given in Table II below, illu6trate the improved light and dark 6tability of the magenta ~Eerrous ion complex dye provided by the pre6ent invention over a conventional magenta dye.
Table II
% Dye Los6 % Dye Los6 (Dark Stability) (Light Stability) Element 60C/70% R.H. 77C/15% R.H. 21 d~y6 _ Control 5.5 3 25 Example 5 not te6ted 0 5 Example 7 Magenta Dye Formation in Silver Halide Element 4'-(4-Octyloxy-3-6ulfophenyl)2,2':6',2"-terpyridine, a magenta dye former wa6 prepared in the following manner.

The chalcone, 2 (4-octyloxycinnamoyl)-pyridine (10.9 g) and the pyridinium ~alt N-(2-pyridylcarbonylmethyl)pyridinium iodide (10.8 g) were combined with 150 ml of methanol, 60ml of glacial acetic acid and 60 g of ammonium acetate.
The resulting mixture was refluxed under argon for 20 hours. After cooling, the precipitate formed was filtered, washed with methanol and recryfi~allized two times from acetonitrile ~o yield 7 g of pure terpyridine, mp 101-102. To 25 ml of cold oleum in a round bottom flask, 4 g of the pure terpyridine wa6 added in ~mell portions over about 30 minutes. The reaction mixture was allowed to come to room temperature and stirred overnight. The reaction mixture was poured onto ice, filtered; the re~ulting solid washed wit~ cold water, then ethanol, and dried in vacuo to provide 3.22 g of product.
A coating di6persion wa~ prepared from 0.18 g of the sulfonated terpyridine described above and 1.8 g of gelatin by diluting to a total weight of 30 g with water (some NH40H was added to give a clear solutionj. A coating composition was made from 8 g of the above dispersion plu6 6.25 g water, 0.5 g of 7.5% saponin 6preading ~id and 0.25 g of 2%
bis(vinyl6ulfonylmethyl) ether hardener. The resulting coating composition was coated on a poly(ethylene terephthalate) film support to provide a donor element.
A strip of the dry coating was soaked in the ferric ion solution descrlbed in Example 1 for about 20 ~econds at room temperature and then laminated to a graduated density silver step-image element (<0.1 mg Ag/m2 to about 19 mg Ag/m2) between nip-rollers. After 60 6econds, the donor element was separated from the step image element and the ~tep-image element was di6carded. The remaining r donor element containing a magenta dye image was wa~hed and air-dried. The Status A den6i~y ranged from 0.09 in the Dmin area to 0.96 in the DmaX
areas.
Example 8 Magenta Dye Formation U~in~
Polymeric Complexin~ Compound Poly[acrylamide-co-4-(2-acrylamidoethoxy)-2,6-di(2-pyridyl)pyridine-co-N-(3-aminopropyl)-methacrylamide hydrochloride] (65:30:5 weight ratio) was prepared in the followlng manner.
To a solution of acrylamide (19.0 g, 0.55 moles), 4-(2-acrylamidoethoxy)-2,6-dl(2-pyridyl)-pyridine (18.0 g, 0.052 moles), ~-(3-aminopropyl)-methacrylamide hydrochloride (3.0 g, 0.017 moles) in t-butanol (420 ml) and methanol (120 ml) was added 2,2'-aæobis(2-methylpropionitrile~ (300 mg) as initiator. The resulting mixture was maintained under a nitrogen atmosphere and heated at 65-70C in a constant temperature water bath. The polymer precipitated and ater 3 hours was filtered. The polymer was dried under vacuum for 2 hour6. The yield was 100%. The polymer had an inherent vi~coæity of 0.38 dl/g in a 0.1 molar solution of tetrabutylammonium bromide in dimethyl 6ulfoxide.
A coating dispersion of the polymer was prepared as follow6: 1 g of the polymer was dissolved in about 45 ml of water. Small ~mount~ of acetic acid were added to give a clear solution. Two ml of 7.5% saponin 601ution were added dropwise ~nd then the total weight wa~ brought to 60 B with water. Coating compositions were prepared from 15 8 of the above dispersion plu~ 0.25 ml of 1%
formaldehyde and coated on poly(ethylene terephthalate) film support to form donor element~.

A strip of the donor element was ~oaked in the ferric solution described in Example 1 for about 20 seconds at room temperature and then laminated to a graduated density silver step-image element (~0.1 mg Ag/m2 to about 19 mg Ag/m2) between nip-rollers. After 60 seconds, the donor element was separated from the step-image element and the step-image element was discarded. The remaining donor element containing a magenta dye image was washed and air-dried. The Status A density ranged from 0.06 in the Dmin area to 1.42 in the DmaX
area.
The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifisation~ can be effected within the spirit and scope of the invention.

Claims (12)

We claim:

1. A process of forming a dye image in an element comprising a support having thereon at least one silver halide emulsion layer which has associated therewith an essentially colorless, immobile compound which is capable of complexing with ferrous ions, said complexing compound containing a complexing moiety represented by the structure:

wherein m is zero or a positive integer 1 to 3, n and p are independently 0 or 1, -- represents a single or double bond, Z is R1-N=, O=, S=, R1-P=, (R1)2P- or (R1)3P=, and when Z is (R1)2P-, n is 1, otherwise n is 0, R1, R2, R3, R4, R5 and R6 are independently hydrogen, amino, hydroxy, mercapto, alkoxy, alkyl, aryl or a heterocyclic moiety, and when R6 is so defined, p is 1 and -- is a single bond, if m is 0, R1 and R2, R2 and R3, and R3 and R4, taken together, can independently represent the carbon and heteroatoms necessary to complete a substituted or unsubstituted carbocyclic or heterocyclic nucleus, or, if m is 1 to 3, R1 and R2, R5 and R6, and R3 and R4 can independently represent the carbon and heteroatoms necessary to complete a substituted or unsubstituted heterocyclic nucleus, and when R5 and R6 are so defined, p is 0 when -- is a double bond, and p is 1 when -- is a single bond, said process comprising the steps of forming an imagewise distribution of a reducing agent for ferric ions, imagewise reducing a ferric compound with said reducing agent to provide an imagewise distribution of ferrous ions, and causing said ferrous ions to react with said complexing compound to form a ferrous ion complex dye.

2. The process of claim 1 wherein Z is R1-N= and m is 0 or 1.

3. The process of claim 1 comprising the steps of imagewise exposing and developing said silver halide emulsion layer to provide in imagewise distribution of metallic silver, physically contacting said metallic silver with a ferric compound, thereby reducing said ferric compound and providing an imagewise pattern of ferrous ions, and causing said ferrous ions to react with said complexing compound to form a ferrous ion-complex dye.

4. A process of forming dye images in an element comprising a support having thereon, in sequence, a red-sensitive emulsion unit which has associated therewith a first essentially colorless, immobile complexing compound which is capable of complexing with ferrous ions to form a cyan dye, a green-sensitive silver halide emulsion unit which has associated therewith a second essentially colorless, immobile complexing compound which is capable of complexing with ferrous ions to form a magenta dye, and a blue-sensitive silver halide emulsion unit which has associated therewith a first essentially colorless, immobile complexing compound which is capable of complexing with ferrous ions to form a yellow dye, said complexing compound containing a complexing moiety represented by the structure:

wherein m is zero or a positive integer 1 to 3, n and p are independently 0 or 1, - represents a single or double bond, Z is R1-N=, 0=, S=, R1-P=, (R1)2P- or (R1)3P=, and when Z is (R1)2P-, n is 1, otherwise n is 0, R1, R2, R3, R4, R5 and R6 are independently hydrogen, amino, hydroxy, mercapto, alkoxy, alkyl, aryl or a heterocyclic moiety, and when R6 is so defined, p is 1 and -- is a single bond, if m is 0, R1 and R2, R2 and R3, and R3 and R4, taken together, can independently represent the carbon and heteroatoms necessary to complete a substituted or unsubstituted carbocyclic or heterocyclic nucleus, or, if m is 1 to 3, R1 and R2, R5 and R6, and R3 and R4 can independently represent the carbon and heteroatoms necessary to complete a substituted or unsubstituted heterocyclic nucleus, and when R5 and R6 are so defined, p is 0 when -- is a double bond, and p is 1 when -- is a single bond, said process comprising the steps of imagewise exposing said element to actinic radiation and developing said element to provide an imagewise distribution of metallic silver in each of said emulsion units, physically contacting said metallic silver in said emulsion units with a ferric compound, thereby reducing said ferric compound and providing an imagewise pattern of ferrous ions in each of said emulsion units, and causing said ferrous ions to react with said complexing compounds to form ferrous ion complex dyes.

5. The process of claim 4 wherein said second complexing compound is a polymer composed of recurring units having the structure:

6. The process of claim 4 wherein said element is a photographic paper product.

7. The process of claim 4 wherein a reversal image is obtained.

8. An element comprising a support having thereon at least one silver halide emulsion layer which has associated therewith an essentially colorless, immobile compound which is capable of complexing with ferrous ions to form a ferrous ion complex dye, said complexing compound of said element containing a complexing moiety represented by the structure:

wherein m is zero or a positive integer 1 to 3, n and p are independently 0 or 1, ? represents a single or double bond, Z is R1-N=, O=, S=, R1-P=, (R1)2P- or (R1)3P=, and when Z is (R1)2P-, n is 1, otherwise n is 0, R1, R2, R3, R4, R5 and R6 are independently hydrogen, amino, hydroxy, mercapto, alkoxy, alkyl, aryl or a heterocyclic moiety, and when R6 is so defined, p is 1 and ? is a single bond, if m is 0, R1 and R2, R2 and R3, and R3 and R4, taken together, can independently represent the carbon and heteroatoms necessary to complete a substituted or unsubstituted carbocyclic or heterocyclic nucleus, or, if m is 1 to 3, R1 and R2, R5 and R6, and R3 and R4 can independently represent the carbon and heteroatoms necessary to complete a substituted or unsubstituted heterocyclic nucleus, and when R5 and R6 are so defined, p is 0 when ? is a double bond, and p is 1 when ? is a single bond.

9. The element of claim 8 wherein Z is R1-N= and m is 0 or 1.

10. A photographic element comprising a support having thereon, in order, a red-sensitive emulsion unit which has associated therewith a first essentially colorless, immobile complexing compound which is capable of complexing with ferrous ions to form a cyan dye, a green-sensitive silver halide emulsion unit which has associated therewith a second essentially colorless, immoble complexing compound which is capable of complexing with ferrous ions to form a magenta dye, and a blue-sensitive silver halide emulsion unit which has associated therewith a first essentially colorless, immobile complexing compound which is capable of complexing with ferrous ions to form a yellow dye, each of said complexing compounds containing a complexing moiety represented by the structure:

wherein m is zero or a positive integer 1 to 3, n and p are independently 0 or 1, -- represents a single or double bond, Z is R1-N=, 0=, S=, R1-P=, (R1)2P- or (R1)3P=, and when Z is (R1)2P-, n is 1, otherwise n is 0, R1, R2, R3, R4, R5 and R6 are independently hydrogen, amino, hydroxy, mercapto, alkoxy, alkyl, aryl or a heterocyclic moiety, and when R6 is so defined, p is 1 and -- is a single bond, if m is 0, R1 and R2, R2 and R3, and R3 and R4, taken together, can independently represent the carbon and heteroatoms necessary to complete a substituted or unsubstituted carbocyclic or heterocyclic nucleus, or, if m is 1 to 3, R1 and R2, R5 and R6, and R3 and R4 can independently represent the carbon and heteroatoms necessary to complete a substituted or unsubstituted heterocyclic nucleus, and when R5 and R6 are so defined, p is 0 when -- is a double bond, and p is 1 when -- is a single bond.

11. The element of claim 10 wherein Z is R1-N= and m is 0 or 1.

12. The element of claim 10 wherein said second complexing compound is a polymer composed of recurring units having the structure: