Silver complexes physical development

Sheppard s mechanism was formulated primarily in reference to direct development (Sheppard, 3 Sheppard and Meyer, 3a) and he assumed that the complex was formed in the act of or as a result of adsorption of the developing agent by the silver halide. Since he did not specifically suggest application of the basic mechanism to physical development, consideration of his mechanism will be deferred until direct development is treated in detail. 

Latent images or faint images in silver metal or other materials can be amplified by redox chemistries other than metal deposition. Several dye-forming redox chemistries have been discovered in which metal complexes serve as catalysts, catalyst precursors or one of the redox partners. The applications of coordination compounds in physical development and image amplification systems are therefore quite broad and diverse. 

Physical development is another type of development, in which soluble and usually complexed silver ion is reduced from solution onto nuclei, which can be latent image nuclei, other suitable nuclei, or silver produced by chemical development. Chemical development and physical development are traditional terms derived... 

The nucleus or development center in physical development can be described as a dual electrode on which the reduction of silver ion to silver and the oxidation of developing agent take place simultaneously. Electrochemical measurements of silver physical development in a hydroquinone/Phenidone physical developer with silver ion complexed with thiocyanate proceed as a catalytic electrode process [39]. 

The rate of the cathodic reduction of silver ion from silver complexes is rapid compared with the anodic oxidation rate of the developing agent, Phenidone. Thus the physical development rate is governed by the anodic reaction [40]. Charge barrier effects have been seen in physical development as well as in chemical development [41]. 

The latent image catalyzes the reduction of silver ion either from the solid silver halide phase, as in chemical development, or from a soluble source of silver ion, as in physical development (Figure 21). One view of chemical development is that interstitial silver ions move through the silver halide crystal and are reduced on the underside of the latent image speck. In purely physical development complexed silver ion moves through the solution and is reduced on the nucleus. In this sense physical development and the early stages of chemical development are similar. 

Figure 21. Chemical and physical development. In chemical development the silver ion source is solid silver halide. In physical development the silver ion source is a soluble silver ion complex,...

The concept of the philosopher s stone which appears under many names, was that of the existence of some substance which should act as a ferment just as yeast acts upon dough, some mystic substance which added to baser metals should induce the transmutation of larger quantities of these to gold or to silver. An idea of this character is of very early origin, hut any definite ideas as to the nature of this substance are lacking, and in the later alchemists, they take an infinity of forms. The philosopher s stone first appears about the seventh century in literature, hut it may be earlier. In the early centuries of alchemy, there was also developed a mass of symbolism which lost nothing of complexity and obscurity with the development of alchemy. Thus, the egg, symbol of the round universe, or of eternity the egg of the philosophers consisted, like the physical universe, of four components, white and yolk a skin and shell. These four constituents again are sometimes said to typify the four metals which form the basis for transmutation, copper, tin, lead and iron. 

Exploration of new complexes with useful antimicrobial activities has stimulated extensive development of synthetic chemistry of silver(I) complexes. The incorporation of novel ligands can moderate the physical and chemical properties of complexes. For example, the bis(diphosphine)silver(I) complexes (which are analogues of the bis(diphosphine)gold(l) complexes with promising antitumor activity compromised by their antimitochondrial activity) were examined for antitumor and antimicrobial activity by... 

The notion of handedness in physical science arose from John Frederick William Herschel s descriptions (2) of quartz. (Parenthetically, it is worth noting here his discovery of the complexation of silver ions by thiosulfate and his comment that the resulting solutions tasted sweet. The eutropic [Au(S203)2] is also bioactive in "myochrysin", the chrysotherapeutic agent for rheumatoid arthritis.) The now well developed relationship between shape and chiroptical spectroscopy has roots in the... 

Albeniz, A. C. Barbera, J. Espinet, P. Lequerica, M. C. Levelut, A. M. Lopez-Marcos, K. J. Serrano, J. L. (2000). Ionic Silver Amino Complexes Displaying Liquid Crystalline Behavior Close to Room Temperature. rr. J. Inorg. Chem., 133-138. Angell, C. A. Byrne, C. A. N. Belieres, J-P., (2007). Parallel Developments in Aprotic and Protic Ionic Liquids Physical Chemistry and Applications. Acc. Chem. Res., 40, 1228-1236. 

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