Silver compounds photolysis

We start the discussion of the group (2) of photo-de-diazoniations in imaging processes by noting that, after silver halide photography, systems based on the photolysis of diazo compounds form the second most important group of imaging processes. 

Photolysis of metal compounds is a method of historical dimension as it has been used since the middle of the nineteenth century, when the light-sensitivity of silver salts was used for photographic purposes. Novel research, especially linked with the names Henglein and Belloni, led to a large extended field in the science of nanoparticles. UV-visible irradiation of Au, Ag, and Pt salts in surfactant or polymer solutions end up with nanoparticle formation. " Compared with hydrogen reduction, photolytic reactions usually give smaller particles with narrower size distribution. ... 

Two examples have been reported of reactions which are the reverse of the isomerizations described so far, in that they involve a reduction in the number of carbon-carbon 7r-bonds and an increase in the number of carbon-carbon a-bonds. Photolysis of cyclo-octa-2,6-dienone (49) in the presence of copper(i) compounds gives the tricyclic ketone (50). The other example is a step in the silver(i)-catalysed benzyne cycloaddition. ... 

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