Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2000-09-21
2001-10-02
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S605000, C430S567000, C430S569000, C430S449000
Reexamination Certificate
active
06296998
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to photographic elements. It particularly relates to an improved silver halide utilizing a water soluble gold complex and a rapid sulfiding agent.
BACKGROUND OF THE INVENTION
There has been considerable effort devoted to improving the sensitivity of silver halide crystals to actinic radiation and thereby increasing the sensitivity of the photographic elements in which they are contained. In this regard, photographic chemists have attempted to vary the components of, or the processes for making, silver halide emulsions. One particularly preferred means to improve sensitivity has been to chemically sensitize photographic emulsions with one or more compounds containing labile atoms of gold, sulfur, selenium, or the like. Examples of chemically sensitized photographic silver halide emulsion layers are described in, for example,
Research Disclosure
, Item No. 308119, December 1989, Section III, and the references listed therein. (
Research Disclosure
is published by Kenneth Mason Publications Ltd, Dudley Annex, 12a North Street, Emsworth, Hampshire PO10 7DQ, England.)
Many gold sensitizers have been described. For example, U.S. Pat. No. 3,503,749 describes the use of water soluble Au(I) thiolate salts comprising one Au atom ligated to one sulfur containing ligand. U.S. Pat. No. 5,220,030 teaches the use of Au(I) compounds with bis mesoionic heterocycles. U.S. Pat. No. 5,252,455 and U.S. Pat. No. 5,391,727 disclose the use of Au(I) macrocyclic cationic sensitizers. U.S. Pat. No. 5,049,484 teaches the use of Au(I) sensitizers having a Au atom ligated to the nitrogen atom of heterocyclic rings. U.S. Pat. No. 5,620,841 discloses the use of gelatin dispersions of a Au(I) thiosulfonato sensitizer with two different ligands, at least one of which is mesoionic, and U.S. Pat. No. 5,700,631 teaches the use of gelatin dispersions of Au(I) thiosulfonato sensitizers with two different ligands, at least one of which is a thioether group. JP 8069075 discusses the use of organic gold sulfide compounds in the sensitization of low-fogging and high contrast silver halide photographic materials. However, all of the above compounds have one or more disadvantages such as lack of water solubility, difficulty of synthesis, or poor stability.
An improved gold sensitizer avoiding the above difficulties has been described by Lok et al in U.S. Pat. No. 5,912,112. Although a more convenient gold source, chemical sensitizations with this material in combination with common sulfur sources such as thiosulfate do not always yield acceptable fog levels.
Other patents relating to Au(I) complexes are U.S. Pat. Nos. 5,945,270 and 6,034,249 of Lok et al.
PROBLEM TO BE SOLVED BY THE INVENTION
Thus, there is still need for a combination of a convenient gold source with a sulfur source that provides lower fog levels while producing acceptable or improved photographic speeds.
SUMMARY OF THE INVENTION
The invention relates to an emulsion comprising bromide grains wherein said grains are chemically sensitized with a water soluble Au(I) complex having the formula
[L—Au—L]M
wherein the complex is symmetrical; L is an organomercapto ligand which has antifogging, stabilizing, or sensitizing properties, and M is a cationic counter ion and a rapid sulfiding agent represented by structure SS-1:
wherein each of the R
1
, R
2
, R
3
, and R4 groups independently represents an alkylene, cycloalkylene, carbocyclic arylene, heterocyclic arylene, alkarylene or aralkylene group; or taken together with the nitrogen atom to which they are attached, R
1
and R
2
or R
3
and R
4
can complete a 5- to 7-membered heterocyclic ring; and
each of the B
1
, B
2
, B
3
, and B
4
groups independently is hydrogen or represents a carboxylic, sulfinic, sulfonic, hydroxamic, mercapto, sulfonamido or primary or secondary amino nucleophilic group, with the proviso that at least one of the B
1
R
1
to B
4
R4 groups contains the nucleophilic group bonded to a urea nitrogen atom through a 1- or 2-membered chain.
ADVANTAGEOUS EFFECT OF THE INVENTION
The invention provides a photographic element with improved fog performance, as well as providing improved or acceptable photographic speed.
DETAILED DESCRIPTION OF THE INVENTION
This invention relates to a photographic element comprising a support and a silver halide emulsion layer, the emulsion layer comprising a water soluble Au(I) complex having the formula
[L—Au—L]M
wherein the complex is symmetrical; L is an organomercapto ligand which has antifogging, stabilizing, or sensitizing properties, and M is a cationic counter ion. This invention further relates to a silver halide photographic element comprising a support and a silver halide emulsion layer, the emulsion layer comprising an organomercapto Au(I) complex having the formula
[(M—SOL)
n
—A—S—Au—S—A—(SOL—M)
n
]M
wherein
M is a cationic counterion;
SOL is a solubilizing group:
A is a substituted or unsubstituted divalent organic linking group;
and n is 1 to 4 and wherein the compound is symmetrical.
This invention also provides a silver halide photographic element comprising a support and a silver halide emulsion layer, the emulsion layer having been chemically sensitized in the presence of an organomercapto Au(I) complex having the above formula.
It further provides a method of preparing a silver halide emulsion comprising precipitating silver halide grains in an aqueous colloidal medium to form an emulsion, heating the emulsion, and adding to the emulsion, either before or during heating, an organomercapto Au(I) complex of the above formula in combination with a rapid sulfiding agent represented by structure SS-1:
wherein each of the R
1
, R
2
, R
3
, and R
4
groups independently represents an alkylene, cycloalkylene, carbocyclic arylene, heterocyclic arylene, alkarylene or aralkylene group; or taken together with the nitrogen atom to which they are attached, R
1
, and R
2
or R
3
and R
4
can complete a 5- to 7-membered heterocyclic ring; and
each of the B
1
, B
2
, B
3,
and B
4
groups independently is hydrogen or represents a carboxylic, sulfinic, sulfonic, hydroxamic, mercapto, sulfonamido or primary or secondary amino nucleophilic group, with the proviso that at least one of the B
1
R
1
to B
4
R
4
groups contains the nucleophilic group bonded to a urea nitrogen atom through a 1- or 2-membered chain.
A preferred group of rapid sulfiding agents having the general SS-1 structure is that
wherein each of the R
1
, R
2
, R
3
, and R4 groups independently represents an alkylene group having 1 to 6 carbon atoms; and
each of the B
1
, B
2
, B
3
, and B
4
groups independently is hydrogen or represents a carboxylic, sulfinic, sulfonic, hydroxamic group;
with the proviso that at least one of the B
1
R
1
to B4R4 groups contains the nucleophilic group bonded to a urea nitrogen atom through a 1- or 2-membered chain.
The novel organomercapto Au(I) complexes contained in the photographic elements of this invention have numerous advantages. They are highly effective sensitizers for silver halide emulsions. They are also highly water soluble. Because of the water solubility of these complexes, the use of costly and time consuming preparation of gel dispersions is unnecessary. Further, there is no need to use large volumes of water for dissolving the complexes.
Unlike prior mixed-ligand gold compounds, the two Au ligands in the complexes of this invention are identical, thus reducing the complexity of preparation. Further, the complexes utilize inexpensive and commercially available starting materials. Another advantage is that the preparation of the gold complexes of the present invention does not utilize dangerous explosive gold fulminates or large quantities of organic solvents.
Additionally, because of the stability of the covalent gold and sulfur bonds, the complexes of the present invention are more stable than those having mesoionic ligands. Indeed, there is evidence that even in acidic solutions, the complexes of the present invention are more stable than those of the mesoioni
Eikenberry Jon N.
Lok Roger
Wilson Robert D.
Eastman Kodak Company
Leipold Paul A.
Letscher Geraldine
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