Cooperative Effects in Switchable Catalysis: Enhancing Double-Click Reaction Yield of Symmetrical Rotaxanes

Abstract

Reversible switching between the closed cyclic dimeric assembly [Cu2(1)2]2+ (OFF state) and the extended dimeric homoleptic complex [FeCu2(1)2]4+ (ON State) by addition/removal of Fe2+ triggered catalysis of a double-click reaction and high yield preparation of [2]rotaxanes. Mechanistic and computational studies provide valuable general insight for double-click strategies by revealing cooperative effects in the second cycloaddition step due to a distance-tolerant preorganization of the first-click product by the two copper(I)-loaded phenanthroline subunits of [FeCu2(1)2]4+.