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

Abstract

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.

Redox-Active Au Nanoparticles Self-Assembled at Liquid–Liquid Interface via C–Au Functionalization for Dye Degradation Electrocatalysis

“…34,39,40 Notably, recently, we have explored the formation of SAMs on Au using electroactive molecules such as organic radicals as well as a ferrocenyl-stilbene analogue (Fc) bearing terminal alkynes. 36,41,37 Based on these precedents and with the goal to achieve covalent robust molecule/metal interactions that ensure suspension stability under electrochemical conditions, herein, we have employed terminal alkynes for the functionalization of Au NPs. In this study, functional redox-active Fc−C�C−Au NP composite films, self-assembled at the LLI, were prepared employing Au NPs stabilized with poly(vinylpyrrolidone) (PVP) as precursors.…”

“…For instance, molecules with terminal alkynes (R–CC–H) have been shown to spontaneously interact with Au surfaces, resulting in stable monolayers with high surface coverage. − The C–Au covalent bond is of particular interest because the high directionality of C–Au σ-bond and the high electronic hybridization between the molecule and the metal leading to stable and reliable interfaces . This approach has been predominantly used for preparing molecular self-assembled monolayers (SAMs) on flat surfaces, only a limited number of studies have been reported on Au NPs. ,, Notably, recently, we have explored the formation of SAMs on Au using electroactive molecules such as organic radicals as well as a ferrocenyl-stilbene analogue (Fc) bearing terminal alkynes. ,, Based on these precedents and with the goal to achieve covalent robust molecule/metal interactions that ensure suspension stability under electrochemical conditions, herein, we have employed terminal alkynes for the functionalization of Au NPs.…”