Coupled electrochemical/Photochemical patterning and erasure of Ag ⁰ Nanoclusters on Au Surfaces

A nitrospiropyran (la) monolayer-modified Au electrode provides an active surface for the photolithographic patterning of an electrode with Ag⁰ nanoclusters. Illumination of the monolayer-modified Au surface through a mask yields nitromerocyanine (1b)-patterned domains on the Au electrode that bind Ag⁺ ions. The electrochemical reduction of the Ag⁺ ions yields stable Ag⁰ nanoclusters on the patterned domains, and this enables the SEM imaging of the resulting microstructures. The photoisomerizable and electroactive nitromerocyanine/Ag⁰ nanoclusters exhibit several important features: (i) By the electrochemical oxidation of Ag⁰ nanoclusters to Ag⁺ ions, the patterned metallic nanoclusters are erased but stored in the form of Ag⁺ ions, confined to the patterned monolayer. The stored information can be retrieved by the electrochemical reduction of the Ag⁺ ions, (ii) The photoisomerization of the nitromerocyanine (1b)-modified domains to the nitrospiropyran (1a) state (λ > 475 nm) coupled to the electrochemical oxidation of the Ag ⁰ nanoclusters to Ag⁺ enables the removal of Ag ⁺ from the surface and its restoration for new patterning, (iii) The orthogonal patterning of the Au surface with Ag⁰ nanocluster structures is accomplished by the stepwise coupled photochemical/electrochemical patterning of the surface by two (or more) irradiation steps through the mask.