Proving Cooperativity of a Catalytic Reaction by Means of Nanoscale Geometry: The Case of Click Reaction

Abstract

Establishing whether a reaction is catalyzed by a single-metal catalytic center or cooperatively by a fleeting complex encompassing two such centers may be an arduous pursuit requiring detailed kinetic, isotopic, and other types of studiesas illustrated, for instance, by over a decade-long work on single-copper versus di-copper mechanisms of the popular “click" reaction. This paper describes a method to interrogate such cooperative mechanisms by a nanoparticle-based platform in which the probabilities of catalytic units being proximal can be varied systematically and, more importantly, independently of their volume concentration. The method relies on geometrical considerations rather than a detailed knowledge of kinetic equations, yet the scaling trends it yield can distinguish between cooperative and non-cooperative mechanisms.

On-nanoparticle monolayers as a solute-specific, solvent-like phase

“…The choice of these thiols ensured good solubility in CHCl 3 , which also was a good solvent for the substrates we envisioned. Additionally, based on our previous works, 33,50 the NP size and the 50 : 50 proportion of gating to catalytic thiols ensured a good balance between the reaction yield and selectivity. Specifically, the yield scales with the proportion of the catalytic thiols but the decreasing fraction of the gating units translates into less specificity towards the substrates.…”