Efficient Routes for the Preparation of Urazole Radical Self-Assembled Monolayers on Gold Surfaces

The functionalization of substrates with radical species has been shown to be a promising strategy to confer novel physical and chemical properties to a surface. Urazole radicals are persistent nitrogen-centered radicals that are insensitive to oxygen, making them desirable targets for the functionalization of surfaces. Here, we succeed in the preparation of self-assembled monolayers (SAMs) of a 1-arylurazole radical on Au surfaces using two different approaches. In the first approach, a SAM of a radical precursor on the gold surface is prepared followed by its chemical oxidation to generate the active urazole radical. In the second route, the radical is generated in solution and subsequently grafted on the Au surface. In both cases, the SAMs exhibit active radical behavior, but the SAM prepared by the first approach demonstrates greater surface coverage of the electroactive urazole radical species.