N-heterocyclic carbenes as clickable molecular anchors for electrochemical surface functionalization of metals and glassy carbon

Abstract

The potential of alkyne-containing NHCs as anchor molecules for electrochemical surface modification is investigated. Using a combination of X-ray photoelectron spectroscopy, atomic force microscopy, fluorescence tagging, and shell-isolated nanoparticle-enhanced Raman spectroscopy, we demonstrate that these NHCs can bind effectively to multiple surfaces and be functionalized via electrochemical copper-catalyzed azide–alkyne cycloaddition. Notably, we extend the scope of substrates beyond metals by demonstrating successful modification of glassy carbon. Compared to diazonium salts, NHC coatings show comparable resistance to sonication while forming films of only ∼4 nm in thickness. This reduced film thickness leads to lower surface passivation, which could offer advantages for electrochemical applications. The versatility of these NHC as molecular anchors is demonstrated through the attachment of electrochemically active TEMPO˙, the immobilization of streptavidin, and the formation of copper coatings. These findings highlight the potential of NHCs as alternatives to thiols and diazonium salts for the design of functional materials, electrodes, and biosensors.