Orthogonal reactivity of metal and multimetal nanostructures for selective, stepwise, and spatially-controlled solid-state modification.

Chemists rely on a toolbox of robust chemical transformations for selectively modifying molecules with spatial and functional precision to make them more complex in a controllable and predictable manner. This manuscript describes proof-of-principle experiments for a conceptually analogous strategy involving the selective, stepwise, and spatially controlled modification of inorganic nanostructures. The key concept is orthogonal reactivity: one component of a multicomponent system reacts with a particular reagent under a specific set of conditions while the others do not, even though they are all present together in the same reaction vessel. Using the chemical conversion of metal nanoparticles into intermetallic, sulfide, and phosphide nanoparticles as representative examples, the concept of orthogonal reactivity is defined and demonstrated for a variety of two- and three-component nanoscale systems. First, solution-phase reactivity data are presented and collectively analyzed for the reaction of metal nanoparticles (Ni, Cu, Rh, Pd, Ag, Pt, Au, Sn) with several metal salt and elemental reagents (Bi, Pb, Sb, Sn, S). From these data, several two- and three-component orthogonal systems are identified. Finally, these results are applied to the spatially selective chemical modification of lithographically patterned surfaces and striped template-grown metal nanowires.