Bis AU(I) sensitizers and their synthesis

Details Bis AU(I) sensitizers and their synthesis Bis AU(I) sensitizers and their synthesis

2002-08-07

2004-02-24

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heavy metal containing

C556S011000, C548S106000, C548S108000, C549S003000, C549S210000, C430S605000

Reexamination Certificate

active

06696586

ABSTRACT:

FIELD OF THE INVENTION
This invention relates organothiosulfonato Au(I) complexes and methods of preparing the organothiosulfonato Au(I) complexes. These compounds are particularly useful as sensitizers for silver halide emulsions. It is also anticipated that these compounds may be useful in the pharmaceutical industry.
BACKGROUND OF THE INVENTION
Color photographic paper is used in a wide variety of photoprocessing machines, which include large-scale processors capable of providing large volumes of photographic prints under conditions of continuous operation, and small-scale processors that are used to produce smaller volumes of photographic prints under conditions of discontinuous operation. These machines are known to differ widely in mechanical design, and the operating conditions for these processors vary widely in ambient temperature and humidity due to the wide variety of environments for use.
To provide a color photographic paper that serves all the different machines and conditions and is tolerant of the wide fluctuations in environment, one must address the variation of color paper performance to changes in heat and humidity at the site of operation. One aspect of these variations relates to the sensitivity of the photographic paper to changes in temperature, otherwise known as heat sensitivity. It is desirable to make photographic materials that are invariant to any changes in environmental temperature, such that the photographic response does not change when the ambient temperature fluctuates during the course of processor operations. Alternatively, satisfactory results can be achieved when the photographic response is neutral with respect to changes in environmental temperature, that is, although the photographic material may have a different response as the temperature changes, the changes are not noticeable to the operator as the effects of temperature in each of the constituent layers are synchronized to annul the effect of the temperature changes. It is known that heat sensitivity of the photographic material is critical to its acceptability for use, and that changes in heat sensitivity can occur when changes are made in the process of manufacturing. Thus, it is highly desirable that manufacturing changes do not degrade heat sensitivity.
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 PO 10 7DQ, England.)
One common gold sensitizer used in the sensitization of silver halide emulsions is aurous sulfide, which is made as a colloidal gelatin dispersion, the exact composition of which is not well characterized. This gold sulfide dispersion can give rise to lot-to-lot variability and undesirable and inconsistent sensitometric performance. The source of this variability may come from side reactions in the preparation of this highly insoluble solid since these reactions produce species, which may be photographically active. Further, because of the highly insoluble nature of gold sulfide, most of the sensitizer added is, in fact, unused during the sensitization. The remaining sensitizer left in the gel/silver halide matrix can affect sensitometry.
Other organo gold compounds 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, and JP 8069075 discusses the use of organic gold sulfide compounds in the sensitization to give low fogging and high contrast silver halide photographic materials. U.S. Pat. No. 5,220,030 teaches the use of Au(I) compounds with bis mesoionic heterocycles; U.S. Pat. Nos. 5,252,455 and 5,391,727 disclose the use of Au(I) macrocyclic cationic sensitizers; and 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. These gold compounds, while being useful sensitizers, are somewhat lacking in solution stability. U.S. Pat. No. 5,945,270 describes the use of water soluble organomercapto Au(I) complex as being useful sensitizers in silver chloride emulsions.
Gold complexes containing the thiosulfonato group have been reported. 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. 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. U.S. Pat. No. 5,939,245 teaches the sensitization of silver chloride emulsions by Au(I) thiosulfonato sensitizers the composition of which contains a thiourea moiety.
Regardless of the extensive activity in this area, there is a continuing need for Au (I) compounds that are effective sensitizers and that are stable, water soluble and well characterized. Further, such compounds must be easily manufacturable from readily available starting materials.
SUMMARY OF THE INVENTION
This invention provides organothiosulfonato Au(I) complexes having the formula
[A—SO
2
S—Au—SSO
2
—A]
n
−
M
+n
wherein
M is a cationic counterion;
A is a substituted or unsubstituted organic group;
and n is 1 to 4; and wherein the compound is symmetrical.
The novel organothiosulfonato Au(I) complexes of this invention have numerous advantages. They are highly effective sensitizers for silver halide emulsions. Although unproven, they may also be useful in the pharmaceutical industry. The compounds are 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 may utilize 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.
The organothiosulfonates used in the preparation of the Au(I) complexes may include the numerous thiosulfonate antifoggants/stabilizers. Because of the sensitizing, antifogging, and stabilizing properties of these thiosulfonate ligands, the Au(I) sensitizers derived from these ligands may also show speed enhancing and antifogging/stabilizing effects in addition to their sensitizing properties. The compounds may particularly have improved heat sensitivity over prior art sensitizers.
DETAILED DESCRIPTION OF THE INVENTION
The organothiosulfonato Au(I) complexes of the invention may be represented by the formula
[A—SO
2
S—Au—SSO
2
—A]
n
−
M
+n
with the complex being symmetrical around the atomic Au. M is a cationic counter ion. Preferably M is an alkali or alkali earth metal, for example, lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium or barium, or an ammonium cation, for example, a tetrabutyl or tetraethyl ammonium group. M may also be, for example, Fe
+4
or Mn
+3
. n is 1 to 4, preferably 1 or 2. A is a substituted or unsubstituted organic radical. Preferably A is an aliphatic, (cyclic or acyclic), aro

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