Click chemistry: An efficient tool to control the functionalization of metallic surfaces with alkyl chains possessing two reactive end groups

Major challenges in the design of devices based on self-assembled monolayers (SAMs) standing in sandwich between two electrodes rely in SAMs of high quality and to simultaneously self-assemble them between two different electrodes, especially in case of Metal-Molecule-Metal junction devices. In this study, we demonstrate the synthesis and the characterization of two ferrocene-based functional molecules with two active thiol/thiolacetate anchoring groups which could be used to bind with two different electrodes. To control the orientation of the molecules at the surface of the bottom electrode, a Copper catalysed Alkyne Azide Cycloaddition (CuAAC) (click chemistry) approach is applied on ultra-smooth template stripped gold substrates. Self-assembly of the two molecules could be obtained in two consecutive steps enabling us to control the orientation and the regularity of the SAMs. Cyclic voltammetry results shows that the SAMs obtained by mean of the two-step procedure are of high quality with more than 60% of the gold surface covered by molecules. We further investigated the SAMs by PM-IRRAS, XPS, ellipsometry and contact angle measurements to investigate the presence of functional groups, individual elements and succession of the click reaction on surface.

Automated summary

The study demonstrates the synthesis and characterization of two ferrocene-based functional molecules with two active thiol/thiolacetate anchoring groups for self-assembly between two different electrodes. The orientation of the molecules at the bottom electrode surface is controlled using CuAAC (click chemistry) on ultra-smooth template stripped gold substrates, enabling high quality self-assembly of SAMs.