Silver compounds chemical sensitization

Again, the precise roles of coordination-compound chemical sensitizers, in most cases, are not understood. In fact, their effects may have little to do with their own coordination chemistry. Many simple salts of gold and other noble metals are effective sensitizers. They also may be added to solutions during silver halide precipitation to produce doped emulsions that have special properties. A variety of compounds that can act as ligands to metal ions are also effective alone as chemical sensitizers, the result of complicated oxidation-reduction, ion replacement and adsorption reactions on the silver halide grain surface. These include polyamines, phosphines and thioether- or thiol-containing compounds. The chemistry of these materials with the silver halide surface is discussed in the reference literature. 

Coordination compounds and coordination chemistry are involved in a number of these steps. Chemical sensitizing agents, antifoggants and stabilizers are discussed separately. This discussion concerns silver halide emulsion precipitation and physical ripening methods. 

The sensitivity of silver NMR chemical shifts is illustrated by a series of studies of silver thiolates and related compounds.65 67 In [(C6H5)4P]2[Ag4(SCH2C6H4CH2S)3]... 

OXALIC ACID (144-62-7) CjHjO. HOOCCOOH Combustible solid heat-sensitive. (combustible <215 F/101°C. Fire Rating 1). Exposure to elevated temperatures, hot surfaces, or flames causes decomposition and the formation of toxic and flammable formic acid and carbon monoxide. Hygroscopic the solution in water is a medium-strong acid. Violent reaction with strong oxidizers, acid chlorides alkali metals bromine, furfuryl alcohol hydrogen peroxide (90%) phosphorus trichloride silver powders sodium, sodium chlorite sodium hypochlorite urea + heat (forms NHj gas, CO2 and CO may explode). Mixture with some silver compounds forms explosive salts of silver oxalate. Incompatible with caustics, mercury, urea. On small fires, use dry chemical powder (such as Purple-K-... 

The three most common forms of chemical sensitization are based on reaction of the AgX with very small quantities of sulfur compounds, salts of gold or other noble metals, and reducing agents. The premier commercial technique for high sensitivity is a combination of the first two. The sulfur compounds react with the AgX to form some silver sulfide on the surface of the crystals. While catalytic mechanisms have been proposed, and enhanced hole trap-... 

Ag(I) ions have long been known to possess potent antimicrobial properties, but the use of silver compounds as pharmaceuticals has been hampered by their unfavourable chemical properties. For example, many Ag(I) complexes are light sensitive, and the insolubility of AgCl often presents problems when compounds come into contact with physiological fluids. Over 100 silver compounds have been evaluated for anticancer activity by the National Cancer Institute, and only 5 have shown at best marginal activity. The burn-treatment compound silver sulphadiazene is insoluble and applied topically to burn wounds. Its antibacterial action may be attributable to the slow release of Ag at the wound site ). 

Photography based on silver halides as the light-sensitive material depends on physical and chemical properties that, although occurring individually in other compounds, form a combination in the silver salts that makes them unique in their... 

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