Nanodot Formation of Ferrocene-Terminated Self-Assembled Monolayers

Abstract

Self-assembly of molecular monolayers is a very useful technique for fabricating chemically modified electrodes with various functions. This technique enables to form a uniform molecular monolayer on a metal surface without guidance from outside. On the other hand, it is still difficult for this technique to fabricate patterned monolayers or to integrate multiple functionality within a monolayer. Although soft-lithography of self-assembled monolayers such as microcontact printing has already been reported, further advancement in forming nanoscale features of molecular monolayers is awaited for creation of multifunctional electrodes. In this study, molecular nanodots are formed on Au(111) surfaces using a novel electrochemical nanolithographic method combining reductive desorption of thiols with AuNP-assisted local stabilization of the monolayers. The left panel of the figure shows a topographic image and I-V curves measured on nanopatterned monolayers of 4-methylbenzenethiols on Au(111) using current-AFM. As a result of the local removal of the molecular monolayers, the exposed surface showed metallic conductivity. On the other hand, the other area showed rather low conductivity with the exponential profile, indicating that the molecular layers remained with nanoscale domains. The right panel shows that average molecular nanodot sizes was controllable by alternating the size of AuNP template or by changing the ionic strength for reductive desorption. Electrochemical responses of ferrocene-terminated monolayer nanodots will be also demonstrated in the talk. Figure (left) I-V curves measured on molecular nanodots and on the exposed Au(111) (right) Average sizes of molecular nanodots vs. sizes of AuNP templates. Figure 1