Electrochemical Multiplexing: Control over Surface Functionalization by Combining a Redox-Sensitive Alkyne Protection Group with "Click"-Chemistry

Local functionalization of surfaces is a current technological challenge. An electrochemically addressable alkyne protection group is presented enabling the site-selective liberation of alkynes exclusively on electrified electrodes. This controlled deprotection is based on a mendione chromophore which becomes a strong enough nucleophile upon reduction to intramolecularly attack the trialkylsilane alkyne protection group. The site-selective liberation of the alkyne is demonstrated by immobilizing the protected alkyne precursor on a transparent TiO2 electrode and subsequently immobilizing red and blue azide dyes by azide-alkyne "click"-chemistry. While the proof-of-principle is based on colorations visible to the bare eye, the technique presented is generic also to nontransparent electrodes, microscale separations, and functional moieties other than dyes. It may open manifold applications where site-selective functionalization is required but hardly realizable with conventional methods.