A Paradigm for the Radical-Mediated Photochemical Synthesis of Metal Nanostructures

Photochemical methods for free radical generation can provide a powerful tool to design new strategies for the synthesis of metal nanostructures. In particular, the Norrish type I cleavage of substituted benzoins can be employed as a source of strongly reducing radicals, described here as “caged electrons.” A key to an efficient nanostructure synthesis relies on the prevention of excited state quenching by the transition metal ions used as metal precursors; the paradigm presented here emphasizes the spatial-temporal strategies that can ensure the survival of excited states so that they can perform as efficient sources of caged electrons. Keywords: photochemistry; ketyl radicals; Norrish reaction; nanoparticles; nanostructures; noble metals; photoreduction; plasmon transition; nanotechnology