Coupled electrochemical/photochemical patterning and erasure of Ag(0) nanoclusters on Au surfaces

A nitrospiropyran (1a) monolayer-modified Au electrode provides an active surface for the photolithographic patterning of an electrode with Ag(0) 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 Ag(0) nanoclusters on the patterned domains, and this enables the SEM imaging of the resulting microstructures. The photoisomerizable and electroactive nitromerocyanine/Ag(0) nanoclusters exhibit several important features: (i) By the electrochemical oxidation of Ag(0) 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 (lambda > 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 Ag(0) nanocluster structures is accomplished by the stepwise coupled photochemical/electrochemical patterning of the surface by two (or more) irradiation steps through the mask.